| 1. |
- Abdel-Magied, Ahmed, et al.
(författare)
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Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis.
- 2014
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X. ; 50:57, s. 7705-7708
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Abdel-Magied, Ahmed F., et al.
(författare)
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Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters-diastereomeric control of enantioselectivity
- 2020
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 49:14, s. 4244-4256
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Tidskriftsartikel (refereegranskat)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.
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| 3. |
- Abdel-Magied, Ahmed F., et al.
(författare)
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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
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 849-850, s. 71-79
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Tidskriftsartikel (refereegranskat)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.
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| 4. |
- Abdel-Magied, Ahmed F., et al.
(författare)
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Synthesis, Characterization and Catalytic Activity Studies of Rhenium Carbonyl Complexes Containing Chiral Diphosphines of the Josiphos and Walphos Families
- 2015
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Ingår i: Journal of Cluster Science. - : Springer Science and Business Media LLC. - 1040-7278 .- 1572-8862. ; 26:4, s. 1231-1252
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Tidskriftsartikel (refereegranskat)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.
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| 5. |
- Abdel-Magied, Ahmed, et al.
(författare)
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[(mu)-Bis(diphenylphosphanyl-kappa P)methane]decacarbonyltri-(mu)-hydrido-trirhenium(I)(3 Re-Re) dichloromethane solvate
- 2011
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Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; 67:12, s. 1601-1816
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Tidskriftsartikel (refereegranskat)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.
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| 6. |
- Ahmed, SJ, et al.
(författare)
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Dppm-substituted ruthenium clusters with capping sulfido and selenido ligands derived from thiourea, tetramethylthiourea and elemental selenium
- 2006
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 691:3, s. 309-322
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Tidskriftsartikel (refereegranskat)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.
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| 7. |
- Akter, H, et al.
(författare)
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Triphenylphosphine-substituted selenido and sulfido clusters of osmium derived from Ph3P=Se or Ph3P=S
- 2005
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 690:21-22, s. 4628-4639
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Tidskriftsartikel (refereegranskat)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.
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| 8. |
- Amenuvor, Gershon, et al.
(författare)
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Novel pyrazolylphosphite- and pyrazolylphosphinite-ruthenium(II) complexes as catalysts for hydrogenation of acetophenone
- 2016
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 45:34, s. 13514-13524
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Tidskriftsartikel (refereegranskat)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.
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| 9. |
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| 10. |
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