| 1. |
- Abdel-Magied, Ahmed, et al.
(author)
-
Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis.
- 2014
-
In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X. ; 50:57, s. 7705-7708
-
Journal article (peer-reviewed)abstract
- Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P*)] (P-P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters. A catalytic mechanism involving Ru3 clusters has been established by DFT calculations.
|
|
| 2. |
- Abdel-Magied, Ahmed F., et al.
(author)
-
Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters-diastereomeric control of enantioselectivity
- 2020
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 49:14, s. 4244-4256
-
Journal article (peer-reviewed)abstract
- Twenty clusters of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P∗)] (P-P∗ = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters. A catalytic mechanism involving an active Ru3 catalyst generated by CO loss from [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P∗)] has been investigated by DFT calculations.
|
|
| 3. |
- Abdel-Magied, Ahmed F., et al.
(author)
-
Synthesis and characterization of chiral phosphirane derivatives of [(μ-H)4Ru4(CO)12] and their application in the hydrogenation of an α,β-unsaturated carboxylic acid
- 2017
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 849-850, s. 71-79
-
Journal article (peer-reviewed)abstract
- Ruthenium clusters containing the chiral binaphthyl-derived mono-phosphiranes [(S)-([1,1'-binaphthalen]-2-yl)phosphirane] (S)-1a, [(R)-(2'-methoxy-1,1'-binaphthyl-2-yl)phosphirane] (R)-1b, and the diphosphirane [2,2'-di(phosphiran-1-yl)-1,1'-binaphthalene] (S)-1c have been synthesized and characterized. The clusters are [(μ-H)4Ru4(CO)11((S)-1a)] (S)-2, [(μ-H)4Ru4(CO)11((R)-1b)] (R)-3, 1,1-[(μ-H)4Ru4(CO)10((S)-1c)] (S)-4, [(μ-H)4Ru4(CO)11((S)-binaphthyl-P(s)(H)Et)] (S,S p)-5, [(μ-H)4Ru4(CO)11((S)-binaphthyl-P(R)(H)Et)] (S,R p)-6, [(μ-H)4Ru4(CO)11((R)-binaphthyl-P(s)(H)Et)] (R,S p)-7, [(μ-H)4Ru4(CO)11((R)-binaphthyl-P(R)(H)Et)] (R,R p)-8 and the phosphinidene-capped triruthenium cluster [(μ-H)2Ru3(CO)9(PEt)] 9. Clusters 5-8 are formed via hydrogenation and opening of the phosphirane ring in clusters (S)-2 and (R)-3. The phosphirane-substituted clusters were found to be able to catalyze the hydrogenation of trans-2-methyl-2-butenoic acid (tiglic acid), but no enantioselectivity could be detected. The molecular structures of (S)-4, (R,S p)-7 and 9 have been determined and are presented.
|
|
| 4. |
- Abdel-Magied, Ahmed F., et al.
(author)
-
Synthesis, Characterization and Catalytic Activity Studies of Rhenium Carbonyl Complexes Containing Chiral Diphosphines of the Josiphos and Walphos Families
- 2015
-
In: Journal of Cluster Science. - : Springer Science and Business Media LLC. - 1040-7278 .- 1572-8862. ; 26:4, s. 1231-1252
-
Journal article (peer-reviewed)abstract
- Ten rhenium carbonyl complexes-[Re(H)(CO)(3)(1a)], [Re-3(mu-H)(3)(CO)(10) (1a)], [Re-2(CO)(9)(2a)], [Re-2(CO)(8)(2a)], [Re-2(CO)(9)(2b)], [{Re-2(CO)(9)}(2)(2b)], [Re-2 (CO)(8)(2b)], [Re-2(CO)(8)(1b)], [Re-2(mu-H)(2)(CO)(6)(2b)] and [Re-3(mu-H)(3)(CO)(11)(2b)]-containing different bidentate chiral phosphine ligands of the Josiphos (1a, 1b) and Walphos (2a, 2b) families have been synthesized and fully characterized (1a: (R)-1-{(S-P)-2-[Bis[3,5-bis(trifluoromethyl) phenyl] phosphino] ferrocenyl} ethyldi(3,5-xylyl) phosphine, 1b: (R)-1-{(S-P)-2-[Di(2-furyl) phosphino] ferrocenyl} ethyldi-tert-butylphosphine, 2a: (R)-1-{(R-P)-2-[2-[Bis(4-methoxy-3,5-dimethylphenyl) phosphino] phenyl] ferrocenyl} ethylbis[3,5-bis(trifluoromethyl) phenyl] phosphine and 2b: (R)-1-{(R-P)-2-[2( Diphenylphosphino) phenyl] ferrocenyl} ethyldicyclohexylphosphine). The phosphine-substituted clusters were tested for hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The catalytic reactions gave reasonable conversion rates (15-88 %) under relatively mild conditions but relatively moderate enantiomeric excesses (8-57 %) were observed. The crystal structures of [ReH(CO)(3)(1a)], [Re-2 (CO)(9)(2a)], [{Re-2(CO)(9)}(2)(2b)] and [Re-2(mu-H)(2)(CO)(6)(2b)] are presented.
|
|
| 5. |
- Abdel-Magied, Ahmed, et al.
(author)
-
[(mu)-Bis(diphenylphosphanyl-kappa P)methane]decacarbonyltri-(mu)-hydrido-trirhenium(I)(3 Re-Re) dichloromethane solvate
- 2011
-
In: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; 67:12, s. 1601-1816
-
Journal article (peer-reviewed)abstract
- In the title compound, [Re(3)(mu-H)(3)(C(25)H(22)P(2))(CO)(10)]center dot CH(2)Cl(2), the three Re atoms form a triangle bearing ten terminal carbonyl groups and three edge-bridging hydrides. The bis(diphenylphosphanyl) methane ligand bridges two Re atoms. Neglecting the Re-Re interactions, each Re atom is in a slightly distorted octahedral coordination environment. The dichloromethane solvent molecule is disordered over two sets of sites with fixed occupancies of 0.6 and 0.4.
|
|
| 6. |
- Ahmed, SJ, et al.
(author)
-
Dppm-substituted ruthenium clusters with capping sulfido and selenido ligands derived from thiourea, tetramethylthiourea and elemental selenium
- 2006
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 691:3, s. 309-322
-
Journal article (peer-reviewed)abstract
- Treatment of [Ru-3(CO)(10)(mu-dppm)] (4) [dppm = bis(diphenylphosphido)methane] with tetramethylthiourea at 66 degrees C gave the previously reported dihydrido triruthenium cluster [Ru-3(mu-H)(2)(mu(3)-S)(CO)(7)(mu-dppm)] (5) and the new compounds [Ru-3(mu(3)-S)(2)(CO)(7)(mu-dppm)] (6), [Ru-3(mu(3)-S)(CO)(7)(mu(3)-CO)(mu-dppm)] (7) and [Ru-3(mu 3-S)eta(I)-C(NMe2)(2)}(CO)(6)(mu(3)-CO)(mu-dppm)] (8) in 6%, 10%, 32% and 9% yields, respectively. Treatment of 4 with thiourea at the same temperature gave 5 and 7 in 30% and 10% yields, respectively. Compound 7 reacts further with tetramethylthiourea at 66 degrees C to yield 6 (30%) and a new compound [Ru-3(mu(3)-S)(2){mu(3)-C(NMe2)(2)}(CO)(6)(mu-dppm)] (9) (8%). Thermolysis of 8 in refluxing THF yields 7 in 55% yield. The reaction of 4 with selenium at 66 degrees C yields the new compounds [Ru-3(mu(3)-Se)(CO)(7)(mu(3)-CO)(mu-dppm)] (12) and [Ru-4(mu(3)-Se)(mu(3)-eta(3)-PhPCH2PPh(C6H4)(CO)(6)(mu-CO)] (11) and the known compounds [Ru-3(mu-H)(2)(mu(3)-Se)(CO)(7)(mu-dppm)] (12) and [Ru-4(mu(3)-Se)(4)(CO)(6)(mu-dppm)] (13) in 29%, 5%, 2% and 5% yields, respectively. Treatment of 10 with tetramethylthiourea at 66 degrees C gives the mixed sulfur-selenium compounds [Ru-3(mu(3)-S)([mu(3)-Se)(CO)(7)(mu-dppm)] (14) and [Ru-3(mu(3)-S)(mu(3)-Se){eta(1)-C(NMe2)(2)}(CO)(6)(mu-dppm)] (15) in 38% and 10% yields, respectively. The single-crystal XRD structures of 6, 7, 8, 10, 14 and 15 are reported.
|
|
| 7. |
- Akter, H, et al.
(author)
-
Triphenylphosphine-substituted selenido and sulfido clusters of osmium derived from Ph3P=Se or Ph3P=S
- 2005
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 690:21-22, s. 4628-4639
-
Journal article (peer-reviewed)abstract
- Cleavage of P=Se bonds occurs readily in the room-temperature treatment of [Os-3(CO) (10)(MeCN)(2)] with Ph3P=Se to give three new compounds, [Os-3(mu(3)-Se)(2)(CO)(8)(PPh3)] (2), [Os-3(mu(3)-Se)( mu(3)-CO)(CO)(7)(PPh3)(2)] (5) and [Os3(mu-OH)(2)(CO)(8)(PPh3)(2)] (6), respectively, and three known compounds, [Os-3(mu(3)-Se)(2)(CO)(9)] (1), [Os-3(mu(3)-Se)(mu-CO)(2)(CO)(7)(PPh3)] (3), and 1,2-[Os-3(CO)(10)(PPh3)(2)] (4). No evidence for any product containing a co-ordinated Ph3P--Se ligand was obtained. The analogous reaction between [OS3(CO)10(MeCN)2] and Ph3P=S produces five new compounds [Os-3(mu(3)-S)(2)(CO)(8)(PPh3)] (7), [Os-3(mu(3)-S)(mu-CO)(2)(CO)(7)(PPh3)] (8), [Os-3(mu(3)-S) (mu(3)- CO)(CO)(7)(PPh3)(2)] (9), [Os-3(mu(3)-)(2)(CO)(7)(PPh3)(2)] (11) and compound 6 in addition to the known compound 4. Treatment of with Me3NO at 50 degrees C gives the trinuclear cluster [Os-3(mu(3)-Se)(2)(CO)(7)(PPh3)(NMe3)] (13) and the hexanuclear cluster [Os-6(mu(3)-Se)(4)(CO)(14) (PPh3)(2)] (12). Treatment of compound 1 with PPh3 and Me3NO at room temperature gives [Os-3(mu(3)-Se)(2)(CO)(7)(PPh3)(2)] (10). Compound 2 reacts with PPh3 similarly to give 10. Compound 3 reacts with elemental selenium at 110 degrees C to give 2. The new compounds 2, 5, 6 and 8 were characterized by single-crystal X-ray diffraction. The compounds 3, 5, 8 and 9 contain Os-3(mu(3)-S) or Os-3(mu(3)-Se)cluster cores with three metal-metal bonds while 2, 7, 10, 11 and 12 contain Os-3(mu(3)-S)(2) or Os(mu(3)-Se)(2) cores two metal-metal bonds. The two hydroxy ligands in the triosmium cluster 6 bridging the open osmium-osmium edge and are probably derived from water. A study of the dynamic exchange of PPh3 ligands in 5 is also reported.
|
|
| 8. |
- Amenuvor, Gershon, et al.
(author)
-
Novel pyrazolylphosphite- and pyrazolylphosphinite-ruthenium(II) complexes as catalysts for hydrogenation of acetophenone
- 2016
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 45:34, s. 13514-13524
-
Journal article (peer-reviewed)abstract
- The new compounds and potential ligands 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiphenlyphosphinite (L1), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L2), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl-diethylphosphite (L3) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L4) were prepared from the reaction of (3,5-(disubstituted)pyrazol-1H-yl)ethanol and the appropriate phosphine chloride. The phosphinite (L1) and phosphites (L2-L4) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L5) were reacted with [Ru(p-cymene)Cl2]2 to afford the ruthenium(ii) complexes [Ru(p-cymene)Cl2(L1)] (1), [Ru(p-cymene)Cl2(L2)] (2), [Ru(p-cymene)Cl2(L3)] (3), [Ru(p-cymene)Cl2(L4)] (4), and [Ru(p-cymene)Cl2(L5)] (5). All ruthenium complexes were characterized by a combination of NMR spectroscopy, elemental analysis and, in selected cases, by single crystal X-ray crystallography. Complexes 1-5 and [Ru(p-cymene)Cl2(L6)] (6) (prepared from 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L6)) were investigated as catalysts for both transfer and molecular hydrogenation of acetophenone to 1-phenylethanol. At 80 °C the percent conversion of acetophenone in transfer hydrogenation was moderate to high over 10 h (42-87%); for molecular hydrogenation acetophenone, conversions were as high as 98% in 6 h.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Begum, Noorjahan, et al.
(author)
-
Chelate and bridge diphosphine isomerization: triosmium and triruthenium clusters containing 1,1-bis(diphenylphosphino)ferrocene (dppf)
- 2007
-
In: Organometallics. - : American Chemical Society (ACS). - 1520-6041 .- 0276-7333. ; 26:25, s. 6462-6472
-
Journal article (peer-reviewed)abstract
- The coordination mode of dppf {dppf = 1,1'-bis(diphenylphosphino)ferrocene} at triosmium and triruthenium carbonyl clusters has been studied. Heating [Os3(CO)12] with dppf in the presence of Me3NO in benzene at 60 C furnishes three triosmium compounds, [Os3(CO)11(1-dppf)] (1), [Os3(CO)10(2-dppf)] (2), and [Os3(CO)10(-dppf)] (3) in 10, 20, and 30% yields, respectively. Reaction of the labile cluster [Os3(CO)10(MeCN)2] with dppf at room temperature also gives 1, 2, and 3 (5, 10, and 35% yields). Treatment of 1, which contains a pendant diphosphine, with Me3NO at room temperature affords 2 via a ring closure reaction, whereas heating 2, in which the dppf ligand is chelating, at 110 C affords the thermodynamically stable bridging isomer 3, in which phosphorus atoms are bound at equatorial positions. Reaction of the unsaturated cluster [Os3(CO)10(-H)2] (4) with dppf in refluxing THF affords the bridging complex [Os3(CO)8(-dppf)(-H)2] (6) in high yield as the sole product. Hydrogenation of 3 with H2 at 110 C at 1 atm also yields 6. Reactions of both the saturated [Os3(CO)10(-dppm)] (7) and electron-deficient [Os3(CO)8{3-Ph2PCH2P(Ph)C6H4}(-H)] (8) with dppf at 110 C and at room temperature respectively yield [Os3(CO)9(-dppm)(1-dppf)] (9) and [Os3(CO)8(-dppm)(2-dppf)] (10). Compound 9 converts to 10 at 110 C via CO loss and phosphorus coordination. Reaction of [Ru3(CO)12] with dppf in the presence of Me3NO affords the dihydroxy-bridged complex, [Ru3(CO)8(-dppf)(-OH)2] (13), together with the previously reported compounds [Ru3(CO)10(-dppf)] (11) and [Ru3(CO)8(-dppf)2] (12).
|
|
| 12. |
- Begum, N, et al.
(author)
-
Dithiolate complexes of manganese and rhenium: X-ray structure and properties of an unusual mixed valence cluster Mn-3(CO)(6)(mu-eta(2)-SCH2CH2CH2S)(3)
- 2005
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 44:26, s. 9887-9894
-
Journal article (peer-reviewed)abstract
- Treatment of Mn-2(CO)(10) with 3,4-toluenedithiol and 1,2-ethanedithiol in the presence of Me(3)NO(.)2H(2)O in CH2CI2 at room temperature afforded the dinuclear complexes Mn-2(CO)(6)(mu-eta(4)-SC6H3(CH3)S-SC6H3(CH3)S) (1), and Mn-2(CO)(6)(mu-eta(4)-SCH2CH2S-SCH2CH2S) (2), respectively. Similar reactions of Re-2(CO)(10) with 3,4-toluenedithiol, 1,2benzenedithiol, and 1,2-ethanedithiol yielded the dirhenium complexes Re-2(CO)(6)(mu-eta(4)-SC6H3(CH3)S-SC6H3(CH3)S) (3), Re-2(CO)(6)(mu-eta(4)-SCH2SC6H4S) (4), and Re-2(CO)(6)(SCH2CH2S-SCH2CH2S) (5), respectively. In contrast, treatment of Mn2(CO)10 with 1,3-propanedithiol afforded the trimanganese compound Mn-3(CO)(6)(mu-eta(2)-SCH2CH2CH2S)(3) (6), whereas Re2(CO)10 gave only intractable materials. The molecular structures of 1, 3, and 6 have been determined by single-crystal X-ray diffraction studies. The dimanganese and dirhenium carbonyl compounds 1-5 contain a binucleating disulfide ligand, formed by interligand disulfide bond formation between two dithiolate ligands identical in structure to that of the previously reported dimanganese complex Mn-2(CO)(6)(mu-eta(4)-SC6H4S-SC6H4S). Complex 6, on the other hand, forms a unique example of a mixed-valence trimangenese carbonyl compound containing three bridging 1,3-propanedithiolate ligands. The solution properties of 6 have been investigated by UV-vis and EPR spectroscopies as well as electrochemical techniques.
|
|
| 13. |
- Begum, Noorjahan, et al.
(author)
-
Reaction of [Ru-3(CO)(12)] with tri(2-furyl)phosphine: Di- and tri-substituted triruthenium and phosphido-bridged diruthenium complexes
- 2008
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 693:8-9, s. 1645-1655
-
Journal article (peer-reviewed)abstract
- Reaction of [Ru-3(CO)(12)] with tri(2-furyl)phosphine, P(C4H3O)(3), at 40 degrees C in the presence of a catalytic amount of Na[Ph2CO] furnishes two triruthenium complexes [Ru-3(CO)(10){P(C4H3O)(3)}(2)] (1) and [Ru-3(CO)(9){P(C4H3O)(3)}(3)] (2) with the ligand coordinated through the phosphorus atom. Treatment of 1 and 2 with Me3NO at 40 degrees C affords the dinuclear phosphido-bridged complexes [Ru-2(CO)(6)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}] (3) and [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}{P(C4H3O)(3)}] (4), respectively, that are formed via phosphorus-carbon bond cleavage of a coordinated phosphine followed by coordination of the dissociated furyl moiety to the diruthenium center in a sigma,pi-alkenyl mode. Reaction of [Ru-3(CO)(12)] with tri(2-furyl) phosphine in refluxing benzene gives, in addition to 3 and 4, low yields of the cyclometallated complex [Ru-3(CO)(9){mu-eta(1),eta(1)-P(C4H3O)(2)(C4H2O)}(2)] (5). Treatment of 3 with EPh3 (E = P, As, Sb) at room temperature yields the monosubstituted derivatives [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}(EPh3)] (E = P, 8; E = As, 9; E = Sb, 10). Similar reactions of 3 with P(C4H3O)(3), P(OMe)(3) and (BuNC)-N-t yield 4, [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}{P(OMe)(3)}] (11) and [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}(NCBut)] (12), respectively. The molecular structures of complexes 3, 4 and 8 have been elucidated by single crystal X-ray diffraction studies. Each complex contains a bridging sigma,pi-alkenyl group and while in 4 the phosphine is bound to the sigma-coordinated metal atom, in 8 it is at the pi-bound atom. Protonation of 3 and 4 gives the hydride complexes [(mu-H)Ru-2(CO)(6)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}](+) (6) and [(mu-H)Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}{P(C4H3O)(3)}] (+) (7), respectively, while heating 3 with dimethylacetylenedicarboxylate (DMAD) in refluxing toluene gives the cyclotrimerization product, C-6(CO2Me)(6).
|
|
| 14. |
- Behrens, A, et al.
(author)
-
Oxomolybdenum(III, IV and V) complexes of thiofunctional ligands
- 2005
-
In: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 358:6, s. 1970-1974
-
Journal article (peer-reviewed)abstract
- Reaction of [MoO2(acac)(2)] with Li2NS2S'(2), (S is a thioether, S' a thiophenolate function) yielded the compound Li-7(thf)(17){MoO}(8)center dot 10thf center dot hexane, where {MoO}(8) represents one [(MoO)-O-IV(NS2S'(2))] 1, three [(MoO)-O-III(NS2S'(2))](-) (2, linked, via the oxo group, to [Li(thf)3](+)) and two [(MoO)-O-V(S'(2))(2)](2-)(2) .A mixed-valent variant of 3, [{(MoO)-O-IV(S'(2))} {(MoO)-O-V(S'(2))}](-) (3b, with an additional [Li(thf)3](+) attached to S'), was also identified. The compounds model features pertinent to oxo-transferases containing the molybdopterin cofactor.
|
|
| 15. |
- Bhunora, Suraj, et al.
(author)
-
The use of Cu and Zn salicylaldimine complexes as catalyst precursors in ring opening polymerization of lactides: ligand effects on polymer characteristics
- 2011
-
In: Applied Organometallic Chemistry. - : Wiley. - 1099-0739 .- 0268-2605. ; 25:2, s. 133-145
-
Journal article (peer-reviewed)abstract
- A range of monomeric tetra-coordinate copper (II) and zinc (II) complexes based on N,O-bidentate salicylaldimine Schiff base ligands has been synthesized and characterized using various spectroscopic techniques. These complexes were then evaluated as initiators in ring-opening polymerization of lactides at both 70 degrees C and 110 degrees C. The effect of structural changes in the complexes on the ability of these compounds to initiate lactide polymerization as well as the impact on the chemical and physical characteristics of the polymers obtained indicate that the coordination geometry of the metal complex, M-O bond length and substituents on the Schiff base ligand all play a role in the catalyst activity. Electronic factors were dominant in the case of the copper complexes while steric factors prevailed in the case of Zn initiators. Both the Zn and Cu complexes exhibit characteristics of living ring opening polymerization. Copyright (C) 2010 John Wiley & Sons, Ltd.
|
|
| 16. |
|
|
| 17. |
|
|
| 18. |
- Busa, Asanda V., et al.
(author)
-
New copper(II) salicylaldimine derivatives for mild oxidation of cyclohexane
- 2018
-
In: Journal of Chemical Sciences. - : Springer Science and Business Media LLC. - 0974-3626 .- 0973-7103. ; 130:6
-
Journal article (peer-reviewed)abstract
- Abstract: Two new salicylaldiminato-copper(II) complexes, [Cu(L1)2] (1) and [Cu(L2)2] (2) (where HL1= 4 -tert-Butyl-2-[(thiophen-2-ylmethylimino)-methyl]-phenol and HL2= 2 , 4 -Di-tert-butyl-6-[(thiophen-2-ylmethylimino)-methyl]-phenol), endowed with a pendant thiophenyl moiety, were synthesized and characterized using standard spectroscopic techniques (FT-IR, UV-Vis, MS) and elemental analysis. Complexes 1 and 2 were unequivocally characterized by single crystal X-ray crystallography, which confirmed bidentate bis-chelation of the deprotonated -L1 and -L2 ligands to the copper (II) centres via the phenoxo and imine atoms forming square planar complexes. The copper(II)-hydroperoxo derivatives of 1 and 2 ([(L1)2CuII-OOH] (3) and [(L2)2CuII-OOH] (4)) were also synthesized and the formation of the active intermediate in solution studied. Complexes 1 and 2 were tested as catalyst precursors in cyclohexane oxidation under mild reaction conditions using hydrogen peroxide (H 2O 2) as a terminal oxidant, and were found to catalyse oxidation of the substrate with yields comparable to similar mononuclear and even multinuclear copper complexes. Graphical Abstract: Synopsis Synthesis, characterisation, and molecular structure of salicylaldiminato-copper(II) complexes, and their catalytic evaluation in the oxidation of cyclohexane employing hydrogen peroxide as a terminal oxidant have been studied. The complexes catalysed conversion of cyclohexane with appreciable yields. [Figure not available: see fulltext.].
|
|
| 19. |
- Caldararu, Octav, et al.
(author)
-
QM/MM study of the reaction mechanism of sulfite oxidase
- 2018
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
-
Journal article (peer-reviewed)abstract
- Sulfite oxidase is a mononuclear molybdenum enzyme that oxidises sulfite to sulfate in many organisms, including man. Three different reaction mechanisms have been suggested, based on experimental and computational studies. Here, we study all three with combined quantum mechanical (QM) and molecular mechanical (QM/MM) methods, including calculations with large basis sets, very large QM regions (803 atoms) and QM/MM free-energy perturbations. Our results show that the enzyme is set up to follow a mechanism in which the sulfur atom of the sulfite substrate reacts directly with the equatorial oxo ligand of the Mo ion, forming a Mo-bound sulfate product, which dissociates in the second step. The first step is rate limiting, with a barrier of 39-49 kJ/mol. The low barrier is obtained by an intricate hydrogen-bond network around the substrate, which is preserved during the reaction. This network favours the deprotonated substrate and disfavours the other two reaction mechanisms. We have studied the reaction with both an oxidised and a reduced form of the molybdopterin ligand and quantum-refinement calculations indicate that it is in the normal reduced tetrahydro form in this protein.
|
|
| 20. |
- Carlsson, Håkan, et al.
(author)
-
Computational modeling of the mechanism of urease.
- 2010
-
In: Bioinorganic Chemistry and Applications. - : Hindawi Limited. - 1687-479X .- 1565-3633. ; 2010
-
Journal article (peer-reviewed)abstract
- In order to elucidate aspects of the mechanism of the hydrolytic enzyme urease, theoretical calculations were undertaken on a model of the active site, using density functional theory. The bridging oxygen donor that has been found in the crystal structures was determined to be a hydroxide ion. The initial coordination of urea at the active site occurs most likely through the urea oxygen to the nickel ion with the lowest coordination number. This coordination can be made without much gain in energy. The calculations also showed that weak coordination of one of the urea amine nitrogen atoms to the second nickel atom is energetically feasible. Furthermore, a proposed mechanism including a tetrahedral intermediate generated by hydrolytic attack on the urea carbon by the bridging hydroxide was modeled, and the tetrahedral intermediate was found to be energetically unfavorable relative to terminal coordination of the substrate (urea).
|
|
| 21. |
- Carlsson, Håkan, et al.
(author)
-
Hydrolytically active tetranuclear nickel complexes with structural resemblance to the active site of urease
- 2002
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 41:20, s. 4981-4983
-
Journal article (peer-reviewed)abstract
- Reaction of the new asymmetric ligand 2-(N-isopropyl-N-((1-methylimidazolyl)methyl)aminomethyl)-6-(N-carboxylm ethyl-N-((1-methylimidazolyl)methyl) aminomethyl)-4-methylphenol (ICIMP) with nickel perchlorate and diphenylacetic acid leads to the formation of tetranuclear nickel complexes, whose crystal structures reveal that they consist of dimers of dimers in which each Ni-2 unit has a coordination environment that is similar to the active site of urease. One complex has been shown to coordinate urea and catalyze the hydrolysis of an organophosphate monoester.
|
|
| 22. |
- Carlsson, Håkan, et al.
(author)
-
Nickel Complexes of Carboxylate-Containing Polydentate Ligands as Models for the Active Site of Urease
- 2004
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 43:26, s. 8252-8262
-
Journal article (peer-reviewed)abstract
- Two new carboxylate-containing polydentate ligands have been synthesized, the symmetric ligand 2,6-bis[N-(N-(carboxylmethyl)-N-((1-methylimidazol)methyl)amine)methyl]-4-methylphenolate (BCIMP) and the corresponding asymmetric ligand 2-(N-isopropyl-N-((1-aminomethyl)-4-methylphenol (ICIMP). The ligands have been used to prepare model complexes for the active site of the dinuclear nickel enzyme urease, viz. [Ni2(BCIMP)Ac2]- (6), [Ni2(BCIMP)(Ph2Ac)2]- (7), [Ni2(ICIMP)(Ph2Ac)2] (14), [Ni4(ICIMP)2(Ph2Ac)2][ClO4]2 (15), [Ni4(ICIMP)2(Ph2Ac)2(DMF)2][ClO4]2 (16), and [Ni4(ICIMP)2(Ph2Ac)2(urea)(H2O)][ClO4]2 (17), where the latter complex contains urea coordinated in a unidentate fashion through the carbonyl oxygen. The N2O-N2O2 donor set of ICIMP provides a good framework for the preparation of urease models, but in some cases tetranuclear nickel complexes are formed due to coordination of the carboxylate moiety of one dinickel-ICIMP unit to one or both of the nickels of a second Ni2 unit. Reactivity and kinetics studies of 7 and 15 show that these model complexes catalyze hydrolysis of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) at basic pH. In this assay, complexes based on the asymmetric ligand ICIMP exhibit a significantly faster rate of hydrolysis than the corresponding BCIMP complexes. Magnetic measurements indicate that there are weak antiferromagnetic interactions between the nickel ions in complex 16.
|
|
| 23. |
- Carlsson, Håkan, et al.
(author)
-
Structural and Functional Models of the Active Site of Zinc Phosphotriesterase
- 2004
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 43:18, s. 5681-5687
-
Journal article (peer-reviewed)abstract
- In an attempt to prepare structural and functional models for the active site of the hydrolytic enzyme zinc phosphotriesterase, five new zinc complexes of the ligands 2,6-bis[N-(N-(carboxylmethyl)-N-((1-methylimidazol)methyl)amine)methyl]-4-methylphenolate (BCIMP) and the corresponding asymmetric ligand 2-(N-isopropyl-N-((1-methylimidazolyl)methyl)aminomethyl)-6-(N-carboxylmethyl-N-((1-methylimidazolyl)methyl)aminomethyl)-4-methylphenol (ICIMP) have been synthesized, viz. Na[Zn2(BCIMP)Ac2] (1), [Zn2(BCIMP)(Ph2Ac)] (2), [Zn2(ICIMP)Ac2] (3), [Zn4(ICIMP)2(Me3Ac)2][ClO4]2 (4), and [Zn4(ICIMP)2(Ph2Ac)2][ClO4]2 (5). The X-ray structure of complex 5 has been determined and reveals that the complex is a dimer of dimers in the solid state, which in solution dissociates to potent structural models. Studies using NMR show that only one carboxylate coligand bridges the dizinc units in the case of diphenyl acetate and pivalate, while the steric bulk of acetate is sufficiently small to permit the coordination of two acetates/dizinc unit. Functional studies involving the hydrolysis/transesterification of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) show that the complex with ICIMP (compound 5) has a significantly higher rate of catalysis than the BCIMP complex (compound 2). This is attributed to the vacant/labile coordination site that is available in the ICIMP complex but not the BCIMP complex.
|
|
| 24. |
- Carlsson, Håkan, et al.
(author)
-
Synthesis and reactivity studies of model complexes for dinuclear active sites in metalloenzymes
- 2001
-
Conference paper (peer-reviewed)abstract
- Several new polydentate and potentially dinucleating ligands have been synthesized in order to model the coordination environments of a number of structurally related dinuclear active sites in metalloenzymes, including methane monooxygenase, the ribonucleotide reductase R2 protein, urease, arginase, red kidney bean purple acid phosphatase and zinc phosphotriesterase.~ Ligands 1 and 2 have proven to be versatilebuilding blocks for the preparation ofhomodinuclear Fe2, Mn2 and Ni2 complexes which funcion as adequate structural models for hydrolytic enzymes. Stepwise syntheses of heterodinuclear Fe-Zn complexes have been achieved using ligand 2. Reactivity studies indicate that some of these model complexes exhibit biomimetic activity. The catalytic mechanisms of some hydrolytic enzymes, e.g. urease and kidney bean purple acid phosphatase, have been probed using a combination of synthetic and computational modelling approaches.
|
|
| 25. |
- Castillo, Ivan, et al.
(author)
-
Bis(benzimidazolyl)amine copper complexes with a synthetic 'histidine brace' structural motif relevant to polysaccharide monooxygenases
- 2014
-
In: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 422, s. 152-157
-
Journal article (peer-reviewed)abstract
- Reaction of Cu2+ salts with the benzimidazole-N-methylated bis[(1-methyl-2-benzimidazolyl)ethyl]amine ligand 2BB results in either bi- or monometallic complexes. Spectroscopic and solid state characterization reveals either square pyramidal or trigonal bipyramidal coordination geometries around the cupric ions. In [{2BBCu(mu-F)}(2)](BF4)(2), the dicopper structure is determined by the bridging nature of the fluoro ligands, which complement the T-shape arrangement of N-3 donors provided by 2BB to define a square pyramidal (or capped distorted tetrahedral) coordination geometry. The monocopper complexes 2BBCuCl(2) and [2BBCu(H2O)(2)](OTf)(2) are characterized by a trigonal bipyramidal geometry both in solution and in the solid state. In all complexes, the T-shape N-3 donor set of 2BB is analogous to the coordination environment of the copper ions provided by a 'histidine brace' and an additional histidine imidazole in the active site of polysaccharide monooxygenases. (C) 2014 Elsevier B. V. All rights reserved.
|
|
| 26. |
- Castillo, Ivan, et al.
(author)
-
Structural, spectroscopic, and electrochemical properties of tri- and tetradentate N-3 and N3S copper complexes with mixed benzimidazole/thioether donors
- 2012
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; 41:31, s. 9394-9404
-
Journal article (peer-reviewed)abstract
- Cupric and cuprous complexes of bis(2-methylbenzimidazolyl)(2-methylthiophene) amine (L-1), bis(2-methylbenzimidazolyl)benzylamine (L-2), bis(2-methylbenzimidazolyl)(2,4-dimethylphenylthioethyl)-amine (L-3), bis(1-methyl-2-methylbenzimidazolyl)benzylamine (Me2L2), and bis(1-methyl-2-methylbenzimidazolyl)(2,4-dimethylphenylthioethyl)amine (Me2L3) have been spectroscopically, structurally, and electrochemically characterised. The thioether-containing ligands L-3 and Me2L3 give rise to complexes with Cu-S bonds in solution and in the solid state, as evidenced by UV-vis spectroscopy and X-ray crystallography. The Cu2+ complexes [(LCuCl2)-Cu-1] (1), [(LCuCl2)-Cu-2] (2) and [(Me2LCuCl)-Cu-3]ClO4 (3(Me,ClO4)) are monomeric in solution according to ESI mass spectrometry data, as well as in the solid state. Their Cu+ analogues [(LCu)-Cu-1]ClO4, [(LCu)-Cu-2]ClO4, [(LCu)-Cu-3]ClO4 (4-6), [(BOC2LCu)-Cu-1(NCCH3)]ClO4 (4(BOC)), [(Me2LCu)-Cu-2(NCCH3)(2)]PF6 (5(Me)) and [(Me2LCu)-Cu-3](2)(ClO4)(2) (6(Me)) are also monomeric in acetonitrile solution, as confirmed crystallographically for 4(BOC) and 5(Me). In contrast, 6(Me) is dimeric in the solid state, with the thioether group of one of the ligands bound to a symmetry-related Cu+ ion. Cyclic voltammetry studies revealed that the bis(2-methylbenzimidazolyl) amine-Cu2+/Cu+ systems possess half-wave potentials in the range -0.16 to -0.08 V (referenced to the ferrocenium-ferrocene couple); these values are nearly 0.23 V less negative than those reported for related bis(picolyl) amine-derived ligands. Based on these observations, the N-3 or N3S donor set of the benzimidazole-derived ligands is analogous to previously reported chelating systems, but the electronic environment they provide is unique, and may have relevance to histidine and methionine-containing metalloenzymes. This is also reflected in the reactivity of [(Me2LCu)-Cu-2(NCCH3)(2)](+) (5(Me)) and [(Me2LCu)-Cu-3](+) (6(Me)) towards dioxygen, which results in the production of the superoxide anion in both cases. The thioether-bound Cu+ centre in 6(Me) appears to be more selective in the generation of O-2(center dot-) than 5(Me), lending evidence to the hypothesis of the modulating properties of thioether ligands in Cu-O-2 reactions.
|
|
| 27. |
- Christ, Jason, et al.
(author)
-
Synthesis and Reactivity of Catecholate Complexes Containing Quadruply Bonded Metal Ions
- 2010
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 49:5, s. 2029-2031
-
Journal article (peer-reviewed)abstract
- Quadruply bonded metal complexes of rhenium and molybdenum have been prepared with tetrachlorocatechol. Structural characterization on the [Re-2(Cl(4)Cat)(4)](2-) anion has shown that it consists of distorted square-planar Re(Cl(4)Cat)(2) units linked by a short (2.2067 angstrom) quadruple Re-Re bond. The addition of tetrachlorocatechol to molybdenum acetate was used to prepare the isoelectronic molybdenum analogue "[Mo-2(Cl(4)Cat)(4)](4-)". This complex was found to be far more reactive than the rhenium dimer. A dimer containing a Mo-Mo double bond, [(Cl(4)Cat)(2)Mo(mu-O)(mu-OCH3)Mo(Cl(4)Cat)(2)](3-), was obtained as the methanolysis product of the complex formed initially, and the oxomolybdenum(V) monomer [MoO(Cl(4)Cat)(2)](-) was formed under more oxidative conditions. Both complexes are oxygen-sensitive, giving [MoO2(Cl(4)Cat)(2)](2-) as the final air-stable complex product.
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
- Czaun, Miklos, et al.
(author)
-
An investigation of Cu(II) and Ni(II)-catalysed hydrolysis of (di)imines
- 2010
-
In: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 363:12, s. 3102-3112
-
Journal article (peer-reviewed)abstract
- The reactions of six diimine ligands with Cu(II) and Ni(II) halide salts have been investigated. The diimine ligands were Ph2C=N(CH2)(n)NC=Ph-2 (n = 2 (Bz(2)en, 1a), 3 (Bz(2)pn, 1b), 4 (Bz2bn, 1c)), N, N'-bis-(2-tert-butylthio- 1-ylmethylenebenzene)-2,2'diamino-biphenyl (2), N,N'-bis-(2-chloro-1-ylmethylenebenzene)-1,3diaminobenzene (3) and N,N'-bis-(2-chloro-1-ylmethylenebenzene)-1,2-ethanediamine (4). Reactions of 1a-c, 2-4 with CuCl2 center dot 2H(2)O in dry ethanol at ambient temperature led to complete or partial hydrolysis of the diimine ligands to ultimately form copper diamine complexes. The non-hydrolyzed complexes of 1b and 1c, [Cu(L)Cl-2] (L = 1b, 1c), could be isolated when the reactions were carried out at low temperatures, and the half-hydrolyzed complex [Cu(Bzpn)Cl-2] could also be identified via X-ray crystallography. Similarly, reactions of 1a or 1b with NiCl2 center dot 6H(2)O or [NiBr2(dme)] led to rapid hydrolysis of the imines and Ni complexes containing half-hydrolyzed 1a (Bzen; [trans-[Ni(Bzen)(2)Br-2]) and 1b (Bzpn; [Ni(Bzpn) Br-2] could be isolated and identified via single crystal X-ray analysis. Kinetic studies were made of the hydrolyses of 1a, 1b in THF and 2 in acetone, in the presence of Cu(II), and of 1a in acetonitrile, in the presence of Ni(II). Activation parameters were determined for the latter reaction and for the copper-catalyzed hydrolysis of 2; the relatively large negative activation entropies clearly indicate rate-determining steps of an associative nature.
|
|
| 33. |
- Das, Biswanath, et al.
(author)
-
A di‑iron(III) μ-oxido complex as catalyst precursor in the oxidation of alkanes and alkenes
- 2022
-
In: Journal of Inorganic Biochemistry. - : Elsevier BV. - 0162-0134. ; 231
-
Journal article (peer-reviewed)abstract
- The oxido-bridged diiron(III) complex [Fe2(μ-O)(μ-OAc)(DPEAMP)2](OCH3) (1), based on a new unsymmetrical ligand with an N4O donor set, viz. [2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-((ethylamino)methyl)-4-methylphenol (HDPEAMP)], has been prepared and characterized by spectroscopic methods and X-ray crystallography. The crystal structure of the complex reveals that each Fe(III) ion is coordinated by three nitrogen and three oxygen donors, two of which are the bridging oxido and acetate ligands. Employing H2O2 as a terminal oxidant, 1 is capable of oxidizing a number of alkanes and alkenes with high activity. The catalytic oxidation of 1,2-dimethylcyclohexane results in excellent retention of configuration. Monitoring of the reaction of 1 with H2O2 and acetic acid in the absence of substrate, using low-temperature UV–Vis spectroscopy, suggests the in situ formation of a transient Fe(III)2-peroxido species. While the selectivity and nature of oxidation products implicate a high-valent iron-oxido complex as a key intermediate, the low alcohol/ketone ratios suggest a simultaneous radical-based process.
|
|
| 34. |
- Das, Biswanath, et al.
(author)
-
A dinuclear zinc(II) complex of a new unsymmetric ligand with an N(5)0(2) donor set; A structural and functional model for the active site of zinc phosphoesterases
- 2014
-
In: Journal of Inorganic Biochemistry. - : Elsevier BV. - 0162-0134 .- 1873-3344. ; 132, s. 6-17
-
Journal article (peer-reviewed)abstract
- The dinuclear complex [Zn-2(DPCPMP)(pivalate)](C10(4)), where DPCPMP is the new unsymmetrical ligand [2-(N-(3-((bis((pyridin-2-yl)methyl)amino)methyl)-2-hydroxy-5-methylbenzyl)-N-((pyridin2-y1)methyl)amino)acetic acid], has been synthesized and characterized. The complex is a functional model for zinc phosphoesterases with dinuclear active sites. The hydrolytic efficacy of the complex has been investigated using bis-(2,4-dinitrophenyl)phosphate(BDNPP), a DNA analog, as substrate. Speciation studies using potentiometric titrations have been performed for both the ligand and the corresponding dizinc complex to elucidate the formation of the active hydrolysis catalyst; they reveals that the dinuclear zinc(II) complexes, [Zn-2(DPCPMP)](2) and [Zn-2(DPCPMP)(OH)1 predominate the solution above pH 4. The relatively high pKa of 8.38 for water deprotonation suggests that a terminal hydroxide complex is formed. Kinetic investigations of BDNPP hydrolysis over the pH range 5.5-11.0 and with varying metal to ligand ratio (metal salt:ligand = 0.5:1 to 3:1) have been performed. Variable temperature studies gave the activation parameters triangle H double dagger = 95.6 kJ mol(-1), triangle S double dagger = 44.8 J mo1(-1) K-1, and 6,triangle G double dagger = 108.0 kJ mo1-1. The cumulative results indicate the hydroxido-bridged dinuclear Zn(II) complex [Zn-2(DPCPMP)(mu-OH)] (+) as the effective catalyst. The mechanism of hydrolysis has been probed by computational modeling using density functional theory (DFF). Calculations show that the reaction goes through one concerted step (S(N)2 type) in which the bridging hydroxide in the transition state becomes terminal and performs a nucleophilic attack on the BDNPP phosphorus; the leaving group dissociates simultaneously in an overall inner sphere type activation. The calculated free energy barrier is in good agreement with the experimentally determined activation parameters.
|
|
| 35. |
- Das, Biswanath, et al.
(author)
-
A dinuclear zinc(II) complex of a new unsymmetric ligand with an N5O2 donor set; A structural and functional model for the active site of zinc phosphoesterases.
- 2014
-
In: Journal of Inorganic Biochemistry. - : Elsevier BV. - 1873-3344 .- 0162-0134. ; 132:Online 13 August 2013, s. 6-17
-
Journal article (peer-reviewed)abstract
- The dinuclear complex [Zn2(DPCPMP)(pivalate)](ClO4), where DPCPMP is the new unsymmetrical ligand [2-(N-(3-((bis((pyridin-2-yl)methyl)amino)methyl)-2-hydroxy-5-methylbenzyl)-N-((pyridin-2-yl)methyl)amino)acetic acid], has been synthesized and characterized. The complex is a functional model for zinc phosphoesterases with dinuclear active sites. The hydrolytic efficacy of the complex has been investigated using bis-(2,4-dinitrophenyl)phosphate (BDNPP), a DNA analog, as substrate. Speciation studies using potentiometric titrations have been performed for both the ligand and the corresponding dizinc complex to elucidate the formation of the active hydrolysis catalyst; they reveals that the dinuclear zinc(II) complexes, [Zn2(DPCPMP)](2+) and [Zn2(DPCPMP)(OH)](+) predominate the solution above pH4. The relatively high pKa of 8.38 for water deprotonation suggests that a terminal hydroxide complex is formed. Kinetic investigations of BDNPP hydrolysis over the pH range 5.5-11.0 and with varying metal to ligand ratio (metal salt:ligand=0.5:1 to 3:1) have been performed. Variable temperature studies gave the activation parameters ΔH(‡)=95.6kJmol(-1), ΔS(‡)=-44.8Jmol(-1)K(-1), and ΔG(‡)=108.0kJmol(-1). The cumulative results indicate the hydroxido-bridged dinuclear Zn(II) complex [Zn2(DPCPMP)(μ-OH)](+) as the effective catalyst. The mechanism of hydrolysis has been probed by computational modeling using density functional theory (DFT). Calculations show that the reaction goes through one concerted step (SN2 type) in which the bridging hydroxide in the transition state becomes terminal and performs a nucleophilic attack on the BDNPP phosphorus; the leaving group dissociates simultaneously in an overall inner sphere type activation. The calculated free energy barrier is in good agreement with the experimentally determined activation parameters.
|
|
| 36. |
- Das, Biswanath, et al.
(author)
-
A Heterobimetallic FeIIIMnII Complex of an Unsymmetrical Dinucleating Ligand : A Structural and Functional Model Complex for the Active Site of Purple Acid Phosphatase of Sweet Potato
- 2014
-
In: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-1948 .- 1099-0682. ; 2014:13, s. 2204-2212
-
Journal article (peer-reviewed)abstract
- The heterodinuclear mixed-valence complex [FeMn(ICIMP)(OAc)(2)Cl] (1) {H2ICIMP = 2-(N-carboxylmethyl)-[N-(N-methylimidazolyl-2-methyl)aminomethyl]-[6-(N-isopropylmethyl)-[N-(N-methylimidazolyl-2-methyl)]aminomethyl-4-methylphenol], an unsymmetrical N4O2 donor ligand} has been synthesized and fully characterized by several spectroscopic techniques as well as by X-ray crystallography. The crystal structure of the complex reveals that both metal centers in 1 are six-coordinate with the chloride ion occupying the sixth coordination site of the Mn-II ion. The phenoxide moiety of the ICIMP ligand and both acetate ligands bridge the two metal ions of the complex. Mossbauer spectroscopy shows that the iron ion in 1 is high-spin Fe-III. Two quasi-reversible redox reactions for the complex, attributed to the (FeMnII)-Mn-III/(FeMnII)-Mn-II (at -0.67 V versus Fc/Fc(+)) and (FeMnII)-Mn-III/(FeMnIII)-Mn-III (at 0.84 V), were observed by means of cyclic voltammetry. Complex 1, with an Fe-III-Mn-II distance of 3.58 angstrom, may serve as a model for the mixed-valence oxidation state of purple acid phosphatase from sweet potato. The capability of the complex to effect organophosphate hydrolysis (phosphatase activity) has been investigated at different pH levels (5.5-11) by using bis(2,4-dinitrophenyl)phosphate (BDNPP) as the substrate. Density functional theory calculations indicate that the substrate coordinates to the Mn-II ion. In the transition state, a hydroxide ion that bridges the two metal ions becomes terminally coordinated to the Fe-III ion and acts as a nucleophile, attacking the phosphorus center of BDNPP with the concomitant dissociation of the leaving group.
|
|
| 37. |
- Das, Biswanath, et al.
(author)
-
An Unsymmetric Ligand with a N5O2 Donor Set and Its Corresponding Dizinc Complex : A Structural and Functional Phosphoesterase Model
- 2018
-
In: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-1948 .- 1099-0682. ; :36, s. 4004-4013
-
Journal article (peer-reviewed)abstract
- To mimic the active sites of the hydrolytic enzyme zinc phosphotriesterase, a new dinucleating unsymmetric ligand, PICIMP (2-{[2-hydroxy-5-methyl-3-({[(1-methyl-1H-imidazol-2-yl)methyl](pyridin-2-ylmethyl)amino}methyl)benzyl][(1-methyl-1H-imidazol-2-yl)methyl]amino}acetic acid), has been synthesized and characterized. The hydrolytic efficacy of the complex solution (PICIMP/ZnCl2 = 1:2) has been investigated using bis-(2,4-dinitrophenyl)phosphate (BDNPP), a DNA analogue substrate. Speciation studies were undertaken by potentiometric titrations at varying pH for both the ligand and the corresponding dizinc complex to elucidate the formation of the active hydrolysis catalyst; these studies reveal that the dinuclear zinc(II) complexes, [Zn-2(PICIMP)](2+) and [Zn-2(PICIMP)(OH)](+) predominate in solution above pH 4. The obtained pK(a) of 7.44 for the deprotonation of water suggests formation of a bridging hydroxide between the two Zn-II ions. Kinetic investigations of BDNPP hydrolysis over the pH range 5.5-10.5 have been performed. The cumulative results indicate the hydroxo-bridged dinuclear Zn-II complex [Zn-2(PICIMP)(mu-OH)](+) as the effective catalyst. Density functional theory calculations were performed to investigate the detailed reaction mechanism. The calculations suggest that the bridging hydroxide becomes terminally coordinated to one of the zinc ions before performing the nucleophilic attack in the reaction.
|
|
| 38. |
- Das, Biswanath, et al.
(author)
-
Catalytic Oxidation of Alkanes and Alkenes by H2O2 with a mu-Oxido Diiron(III) Complex as Catalyst/Catalyst Precursor
- 2015
-
In: European Journal of Inorganic Chemistry. - : Wiley. - 1099-0682 .- 1434-1948. ; :21, s. 3590-3601
-
Journal article (peer-reviewed)abstract
- A new mu-oxo diiron(III) complex of the lithium salt of the pyridine-based unsymmetrical ligand 3-[(3-{[bis(pyridin-2-ylmethyl)amino]methyl}-2-hydroxy-5-methylbenzyl)(pyridin2-ylmethyl)amino] propanoate (LiDPCPMPP), [Fe-2(mu-O)(LiDPCPMPP)(2)](ClO4)(2), has been synthesized and characterized. The ability of the complex to catalyze oxidation of several alkanes and alkenes has been investigated by using CH3COOH/H2O2 (1:1) as an oxidative system. Moderate activity in cyclohexane oxidation (TOF = 33 h(-1)) and good activity in cyclohexene oxidation (TOF = 72 h(-1)) were detected. Partial retention of configuration (RC = 53%) in cis- and trans-1,2-dimethylcyclohexane oxidation, moderate 3 degrees/2 degrees selectivity (4.1) in adamantane oxidation, and the observation of a relatively high kinetic isotope effect for cyclohexane oxidation (KIE = 3.27) suggest partial metal-based oxidation, probably in tandem with free-radical oxidation. Low-temperature UV/Vis spectroscopy and mass spectrometric studies in the rapid positive detection mode indicate the formation of a transient peroxido species, [Fe-2(O)(O-2)-(LiDPCPMPP)(2)](2+), which might be an intermediate in the metal-based component of the oxidation process.
|
|
| 39. |
- Das, Biswanath, et al.
(author)
-
Di- and tetrairon(III) μ-oxido complexes of an N3S-donor ligand : Catalyst precursors for alkene oxidations
- 2019
-
In: Frontiers in Chemistry. - : Frontiers Media SA. - 2296-2646. ; 7:MAR
-
Journal article (peer-reviewed)abstract
- The new di- and tetranuclear Fe(III) μ-oxido complexes [Fe 4 (μ-O) 4 (PTEBIA) 4 ](CF 3 SO 3 ) 4 (CH 3 CN) 2 ] (1a), [Fe 2 (μ-O)Cl 2 (PTEBIA) 2 ](CF 3 SO 3 ) 2 (1b), and [Fe 2 (μ-O)(HCOO) 2 (PTEBIA) 2 ](ClO 4 ) 2 (MeOH) (2) were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thio)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex 1a features four μ-oxido bridges, while in dinuclear 1b, the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) Å. In 2, two Fe(III) centers are bridged by one oxido and two formate units, the latter likely formed by methanol oxidation. Complexes 1a and 1b show broad sulfur-to-iron charge transfer bands around 400-430 nm at room temperature, consistent with mononuclear structures featuring Fe-S interactions. In contrast, acetonitrile solutions of 2 display a sulfur-to-iron charge transfer band only at low temperature (228 K) upon addition of H 2 O 2 /CH 3 COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H 2 O 2 as oxidant, but with low product selectivity. High valent iron-oxo intermediates could not be detected by UV-vis spectroscopy or ESI mass spectrometry. Rather, evidence suggest preferential ligand oxidation, in line with the relatively low selectivity and catalytic activity observed in the reactions.
|
|
| 40. |
- Das, Biswanath, et al.
(author)
-
Water oxidation catalyzed by molecular di- and nonanuclear Fe complexes: importance of a proper ligand framework
- 2016
-
In: Dalton Transactions. - : ROYAL SOC CHEMISTRY. - 1477-9226 .- 1477-9234. ; 45:34, s. 13289-13293
-
Journal article (peer-reviewed)abstract
- The synthesis of two molecular iron complexes, a dinuclear iron(III,III) complex and a nonanuclear iron complex, based on the di-nucleating ligand 2,2-(2-hydroxy-5-methyl-1,3-phenylene)bis(1H-benzo[d]imidazole-4-carboxylic acid) is described. The two iron complexes were found to drive the oxidation of water by the one-electron oxidant [Ru(bpy)(3)](3+).
|
|
| 41. |
- Das, Biswanath, et al.
(author)
-
(μ-Acetato-κ(2) O:O')[μ-2,6-bis-({bis-[(pyri-din-2-yl-κN)meth-yl]amino-κN}meth-yl)-4-methyl-phenolato-κ(2) O:O](metha-nol-κO)dizinc bis-(perchlorate).
- 2014
-
In: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; 70:Pt 4, s. 120-121
-
Journal article (peer-reviewed)abstract
- The binuclear title complex, [Zn2(C33H33N6O)(CH3COO2)(CH3OH)](ClO4)2, was synthesized by the reaction between 2,6-bis-({[bis-(pyridin-2-yl)meth-yl]amino}-meth-yl)-4-methyl-phenol (H-BPMP), Zn(OAc)2 and NaClO4. The two Zn(II) ions are bridged by the phenolate O atom of the octadentate ligand and the acetate group. An additional methanol ligand is terminally coordinated to one of the Zn(II) ions, rendering the whole structure unsymmetric. Other symmetric dizinc complexes of BPMP have been reported. However, to the best of our knowledge, the present structure, in which the two Zn(II) ions are distinguishable by the number of coordinating ligands and the coordination geometries (octahedral and square-pyramidal), is unique. The dizinc complex is a dication, and two perchlorate anions balance the charge. The -OH group of the coordinating methanol solvent mol-ecule forms a hydrogen bond with a perchlorate counter-anion. One of the anions is disordered over two sets of sites with an occupancy ratio of 0.734 (2):0.266 (2).
|
|
| 42. |
- Daver, Henrik, et al.
(author)
-
Theoretical Study of Phosphodiester Hydrolysis and Transesterification Catalyzed by an Unsymmetric Biomimetic Dizinc Complex
- 2016
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 55:4, s. 1872-1882
-
Journal article (peer-reviewed)abstract
- Density functional theory calculations have been used to investigate the reaction mechanisms of phosphodiester hydrolysis and transesterification catalyzed by a dinuclear zinc complex of the 2-(N-isopropyl-N-((2-pyridyl)methyl)-aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)amino-methyl)-4-methylphenol (IPCPMP) ligand, mimicking the active site of zinc phosphotriesterase. The substrates bis(2,4)-dinitrophenyl phosphate (BDNPP) and 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) were employed as analogues of DNA and RNA, respectively. A number of different mechanistic proposals were considered, with the active catalyst harboring either one or two hydroxide ions. It is concluded that for both reactions the catalyst has only one hydroxide bound, as this option yields lower overall energy barriers. For BDNPP hydrolysis, it is suggested that the hydroxide acts as the nucleophile in the reaction, attacking the phosphorus center of the substrate. For HPNP transesterification, on the other hand, the hydroxide is proposed to act as a Bronsted base, deprotonating the alcohol moiety of the substrate, which in turn performs the nucleophilic attack. The calculated overall barriers are in good agreement with measured rates. Both reactions are found to proceed by essentially concerted associative mechanisms, and it is demonstrated that two consecutive catalytic cycles need to be considered in order to determine the rate-determining free energy barrier.
|
|
| 43. |
- Deeming, Antony J, et al.
(author)
-
Oxidative addition of silanes R3SiH to the unsaturated cluster [Os3(µ-H){µ3-Ph2PCH2PPh(C6H4)}(CO)8]: Evidence for reversible silane formation in the dynamic behaviour of [Os3(µ-H)(SiR3)(CO)9(µ-dppm)]
- 2004
-
In: Dalton Transactions. - 1477-9234. ; 2004:21, s. 3709-3714
-
Journal article (peer-reviewed)abstract
- Oxidative addition of the silanes R3SiH (R3= Ph3, Et3, EtMe2) to the unsaturated cluster [Os3(µ-H){µ3-Ph2PCH2PPh(C6H4)}(CO)8] leads to the saturated clusters [Os3(µ-H)(SiR3)(CO)9(µ-dppm)](SiR3= SiPh31, SiEt32 and SiEtMe23) and the unsaturated clusters [Os3(µ-H)2(SiR3){µ3-Ph2PCH2PPh(C6H4)}(CO)7](SiR3= SiPh34, SiEt35 and SiEtMe26). Structures are based on spectroscopic evidence and a XRD structure of [Os3(µ-H)(SiPh3)(CO)9(µ-dppm)]1 in which all non-CO ligands are coordinated equatorially and the hydride and the silyl groups are mutually cis. From variable-temperature 1H NMR spectra of the SiEt3 compound 2, exchange of the P nuclei is clearly apparent. Simultaneous migrations of the SiEt3 group and of the hydride from one Os–Os edge to another generate a time-averaged mirror plane in the molecule. VT 1H NMR spectra of the somewhat less bulky compound [Os3(µ-H)(SiMe2Et)(CO)9(µ-dppm)]3 have been analysed. Two isomers 3a and 3b are observed with the hydride ligand located on different Os–Os edges. Synchronous migration of the hydride and SiMe2Et groups is faster than the observed interconversion of isomers which occurs by hydride migration alone. The synchronous motion of H and SiR3only occurs when these ligands are mutually cis as in the major isomer 3a and we propose that this process requires the formation of a transient silane complex of the type [Os3(2-HSiR3)(CO)9(µ-dppm)]. Turnstile rotation within an Os(CO)3(2-HSiR3) group leads to the observed exchange within the major isomer 3a without exchange with the minor isomer. This process is not observed for the minor isomer 3b because the hydride and the silyl group are mutually trans. Protonation to give [Os3(µ-H)2(SiR3)(CO)9(µ-dppm)]+ totally suppresses the dynamic behaviour because there are no edge vacancies.
|
|
| 44. |
- Deeming, AJ, et al.
(author)
-
Mechanisms of concurrent hydride migration processes in a triruthenium cluster capped by a phenylphosphinidene (PPh) ligand
- 2005
-
In: European Journal of Inorganic Chemistry. - : Wiley. - 1099-0682 .- 1434-1948. ; :21, s. 4352-4360
-
Journal article (peer-reviewed)abstract
- Two methods were used to synthesise [Ru-3(mu-H)(2)(mu(3)-PPh)-(CO)(7) (mu-dppm)] (3) (dppm = Ph2PCH2PPh2), the subject of this paper. Treatment of [Ru-3(CO)(10)(mu-dppm)] (1) with phenylphosphane in refluxing THF gave both [Ru-3(mu-H)(2)(mu-PHPh)-(CO)(8)(mu-dppm)] (2) and [Ru-3(mu-H)(2)(mu(3)-PPh)(CO)(7)(mu-dppm)] (3). Cluster 2 converts to 3 in refluxing THF. Alternatively the phenylphosphinidene cluster [Ru-3(mu-H)(2)(mu(3)-PPh)(CO)(9)] (4), prepared by the reported method of treating [Ru-3(CO)(12)] with phenylphosphane, reacts with dppm to produce cluster 3. The single-crystal X-ray structures of 2 and 3 are reported. Hydride mobility in [Ru-3(mu-H)(2)(mu(3)-PPh)(CO)(7)(mu-dppm)] (3) was analysed by variable-temperature H-1 and P-31(H-1) NMR methods. The variations in the spectra with temperature could not be interpreted by a single process, several of which were explored and which gave inadequately matching computed and experimental spectra. However, the spectra were successfully analysed by two concurrent processes, both involving the migration of hydride ligands between Ru-Ru edges. The faster process leads to the exchange of the nonequivalent phosphorus nuclei but not hydride exchange, whereas the hydrides are also exchanged in the slower process. Both processes require hydride ligand migration from one Ru-Ru edge to a vacant one. The hydride ligand bridging the same pair of ruthenium atoms as the dppm ligand is the slower to migrate.
|
|
| 45. |
- Denler, Melissa C., et al.
(author)
-
Mn IV -Oxo complex of a bis(benzimidazolyl)-containing N5 ligand reveals different reactivity trends for Mn IV -oxo than Fe IV -oxo species
- 2019
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 48:15, s. 5007-5021
-
Journal article (peer-reviewed)abstract
- Using the pentadentate ligand (N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, 2pyN2B), presenting two pyridyl and two (N-methyl)benzimidazolyl donor moieties in addition to a central tertiary amine, new Mn II and Mn IV -oxo complexes were generated and characterized. The [Mn IV (O)(2pyN2B)] 2+ complex showed spectroscopic signatures (i.e., electronic absorption band maxima and intensities, EPR signals, and Mn K-edge X-ray absorption edge and near-edge data) similar to those observed for other Mn IV -oxo complexes with neutral, pentadentate N 5 supporting ligands. The near-IR electronic absorption band maximum of [Mn IV (O)(2pyN2B)] 2+ , as well as DFT-computed metric parameters, are consistent with the equatorial (N-methyl)benzimidazolyl ligands being stronger donors to the Mn IV center than the pyridyl and quinolinyl ligands found in analogous Mn IV -oxo complexes. The hydrogen- and oxygen-atom transfer reactivities of [Mn IV (O)(2pyN2B)] 2+ were assessed through reactions with hydrocarbons and thioanisole, respectively. When compared with related Mn IV -oxo adducts, [Mn IV (O)(2pyN2B)] 2+ showed muted reactivity in hydrogen-atom transfer reactions with hydrocarbons. This result stands in contrast to observations for the analogous Fe IV -oxo complexes, where [Fe IV (O)(2pyN2B)] 2+ was found to be one of the more reactive members of its class.
|
|
| 46. |
- Dimitrakopoulou, Anastasia, et al.
(author)
-
Synthesis, structure and interactions with DNA of novel tetranuclear, [Mn-4(II/II/II/IV)] mixed valence complexes
- 2008
-
In: Journal of Inorganic Biochemistry. - : Elsevier BV. - 1873-3344 .- 0162-0134. ; 102:4, s. 618-628
-
Journal article (peer-reviewed)abstract
- Reaction of Mn(II) with phenoxyalkanoic acids and di-2-pyridyl ketone oxime (Hpko) leads to neutral tetranuclear complexes of the general formula Mn-4(O)(pko)(4)(phenoxyalkanoato)(4) (phenoxyalkanoic acids: H-mcpa = 2-methyl-4-chloro-phenoxy-acetic acid, H-2,4,5-T = 2,4.5-trichloro-phenoxy-acetic acid or H3,4-D = 3,4-dichloro-phenoxy-acetic acid). The compounds were synthesized by adding di2-pyridyl ketone oxime to MnCl2 in the presence of the sodium salts of the alkanoic acids in methanol. The crystal structure of Mn-4(II/II/ II/IV)(O)(pko)4(()2,4,5-T)(4) . 2.5CH(3)OH . 0.25H(2)O 1 shows that the complex consists of a [Mn-4( mu(4)-O)](8+) core with a Mn(IV) and 3 Mn(II) ions in octahedral environment and a mu(4)-O atom bridging the four manganese ions. Spectroscopic studies of the interaction of these tetranuclear clusters with DNA showed that these compounds bind to dsDNA. The binding strength of the Mn-4(II/II/II/ IV)(O)(pko)(4)(2,4,5-T)(4) complex for calf thymus DNA is equal to 1.1 X 10(4) M-1. Among the deoxyribonucleotides they bind preferentially to deoxyguanylic acid (dGMP). Competitive studies with ethidium bromide (EthBr) showed that the Mn-4(II/II/II/ IV)(O)(pko)(4)(2,4,.5-T)(4) complex exhibited the ability to displace the DNA-bound EthBr indicating that the complex binds to DNA via intercalation in strong competition with EthBr for the intercalative binding site. Additionally, DNA electrophoretic mobility experiments showed that all three complexes, at low cluster concentration, are obviously capable of binding to pDNA causing its cleavage (relaxation) at physiological pH and temperature. At higher cluster concentration, catenated dimer forms of pDNA was formed.
|
|
| 47. |
|
|
| 48. |
- Dupe, Antoine, et al.
(author)
-
Dioxomolybdenum(VI) and -tungsten(VI) Complexes with Multidentate Aminobisphenol Ligands as Catalysts for Olefin Epoxidation
- 2015
-
In: European Journal of Inorganic Chemistry. - : Wiley. - 1099-0682 .- 1434-1948. ; :21, s. 3572-3579
-
Journal article (peer-reviewed)abstract
- The synthesis of four molybdenum and tungsten complexes bearing tetradentate tripodal amino bisphenolate ligands with either hydroxyethylene (1a) or hydroxyglycolene (1b) substituents is reported. The molybdenum dioxo complexes [MoO2L] (L = 2a, 2b) and tungsten complexes [WO2L] (3a, 3b) were synthesized using [MoO2(acac)(2)] and [W(eg)(3)] (eg = 1,2-ethanediolato, ethylene glycolate), respectively, as precursors. All complexes were characterized by spectroscopic means as well as by single-crystal X-ray diffraction analyses. The latter reveal, in all cases, hexacoordinate complexes in which the hydrogen atom of the hydroxy group is involved in hydrogen bonding with one of the metal oxo groups. In the case of the glycol substituent, the ether oxygen atom is coordinated to the metal whereas the hydroxy group remains uncoordinated. The complexes were tested as catalysts in the epoxidation of cyclooctene under eco-friendly conditions, using an aqueous solution of H2O2 as the oxidant and dimethyl carbonate (DMC) as solvent or neat conditions, as substitutes for chlorinated solvents. Molybdenum complexes 2a and 2b showed good catalytic activity using H2O2 without added solvent, and tungsten complexes 3a and 3b showed very high activity in the epoxidation of cyclooctene using H2O2 and DMC as solvents.
|
|
| 49. |
- Durigon, Daniele C., et al.
(author)
-
The influence of thioether-substituted ligands in dicopper(II) complexes : Enhancing oxidation and biological activities
- 2024
-
In: Journal of Inorganic Biochemistry. - 0162-0134. ; 256
-
Journal article (peer-reviewed)abstract
- This paper describes the synthesis, structural analysis, as well as the magnetic and spectroscopic characterizations of three new dicopper(II) complexes with dinucleating phenol-based ligands containing different thioether donor substituents: aromatic (1), aliphatic (2) or thiophene (3). Temperature-dependent magnetometry reveals the presence of antiferromagnetic coupling for 1 and 3 (J = −2.27 cm−1 and -5.01 cm−1, respectively, H = -2JS1S2) and ferromagnetic coupling for 2 (J = 5.72 cm−1). Broken symmetry DFT calculations attribute this behavior to a major contribution from the dz2 orbitals for 1 and 3, and from the dx2-y2 orbitals for 2, along with the p orbitals of the oxygens. The bioinspired catalytic activities of these complexes related to catechol oxidase were studied using 3,5-di-tert-butylcatechol as substrate. The order of catalytic rates for the substrate oxidation follows the trend 1 > 2 > 3 with kcat of (90.79 ± 2.90) × 10−3 for 1, (64.21 ± 0.99) × 10−3 for 2 and (14.20 ± 0.32) × 10−3 s−1 for 3. The complexes also cleave DNA through an oxidative mechanism with minor-groove preference, as indicated by experimental and molecular docking assays. Antimicrobial potential of these highly active complexes has shown that 3 inhibits both Staphylococcus aureus bacterium and Epidermophyton floccosum fungus. Notably, the complexes were found to be nontoxic to normal cells but exhibited cytotoxicity against epidermoid carcinoma cells, surpassing the activity of the metallodrug cisplatin. This research shows the multifaceted properties of these complexes, making them promising candidates for various applications in catalysis, nucleic acids research, and antimicrobial activities.
|
|
| 50. |
- Ekengard, Erik, et al.
(author)
-
A pyrazine amide – 4-aminoquinoline hybrid and its rhodium and iridium pentamethylcyclopentadienyl complexes; evaluation of anti-mycobacterial and anti-plasmodial activities
- 2017
-
In: Journal of the Mexican Chemical Society. - 1870-249X. ; 61:2, s. 158-166
-
Journal article (peer-reviewed)abstract
- The synthesis and characterization of N-(2-((7-chloroquino-lin-4-yl)amino)ethyl)pyrazine-2-carboxamide (L), an aminoquinoline – pyrazinamide hybrid, and the complexes (N-(2-((7-chloroquino-lin-4-yl)amino)ethyl)pyrazine-2-carboxamide)(cyclopentadienyl) chlorido-rhodium or iridium hexafluorophosphate ([M(L)(Cp*)Cl] PF6; M = Rh, Ir) and the corresponding chlorido salts ([M(L)(Cp*) Cl]Cl; M = Rh, Ir) are described. The ligand and the hexafluorophosphate salts of the metal complexes have been evaluated for anti-plasmodial and anti-mycobacterial activity. The rhodium and the iridium complexes were significantly more active against M. tuberculosis than the free ligand. The crystallographically determined molecular structures of complexes (N-(2-((7-chloroquinolin-4-yl)amino)ethyl) pyrazine-2-carboxamide)(cyclopentadienyl) chlororhodium hexafluoro-phosphate and (N-(2-((7-chloroquinolin-4-yl)amino)ethyl)pyr-azine-2-carboxamide)(cyclopentadienyl)chloro-iridium chloride are presented.
|
|
