| 1. |
- Abdel-Magied, Ahmed F., et al.
(author)
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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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In: Journal of Cluster Science. - : Springer Science and Business Media LLC. - 1040-7278 .- 1572-8862. ; 26:4, s. 1231-1252
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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.
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| 2. |
- Bellini, Daniele, et al.
(author)
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Allylic and Allenylic Dearomatization of Indoles promoted by Graphene Oxide via Covalent Grafting Activation Mode
- 2020
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In: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 26:46, s. 10427-10432
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Journal article (peer-reviewed)abstract
- The site‐selective allylative and allenylative dearomatization of indoles with alcohols is performed under carbocatalytic regime in the presence of graphene oxide (GO, 10 wt% loading) as the promoter. Metal‐free conditions, absence of stoichiometric additive, environmentally friendly conditions (H2O/CH3CN, 55 °C, 6 h), broad substrate scope (33 examples, yield up to 92%) and excellent site‐ and stereoselectivity characterize the present methodology. Moreover, a covalent activation model exerted by GO functionalities was corroborated by spectroscopic, experimental and computational evidences. Recovering and regeneration of the GO catalyst via simple acidic treatment was also documented.
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| 3. |
- Ekengard, Erik, et al.
(author)
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A pyrazine amide – 4-aminoquinoline hybrid and its rhodium and iridium pentamethylcyclopentadienyl complexes; evaluation of anti-mycobacterial and anti-plasmodial activities
- 2017
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In: Journal of the Mexican Chemical Society. - 1870-249X. ; 61:2, s. 158-166
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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.
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| 4. |
- Ekengard, Erik, et al.
(author)
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Pentamethylcyclopentadienyl-rhodium and iridium complexes containing (N^N and N^O) bound chloroquine analogue ligands: synthesis, characterization and antimalarial properties.
- 2016
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; 45:9, s. 3905-3917
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Journal article (peer-reviewed)abstract
- The synthesis and characterization of twenty new pentamethylcyclopentadienyl-rhodium and iridium complexes containing N^N and N^O-chelating chloroquine analogue ligands are described. The in vitro antimalarial activity of the new ligands as well as the complexes was evaluated against the chloroquine sensitive (CQS) NF54 and the chloroquine resistant (CQR) Dd2 strains of Plasmodium falciparum. The antimalarial activity was found to be good to moderate; although all complexes are less active than artesunate, some of the ligands and complexes showed better activity than chloroquine (CQ). In particular, rhodium complexes were found to be considerably more active than iridium complexes against the CQS NF54 strain. Salicylaldimine Schiff base ligands having electron-withdrawing groups (F, Cl, Br, I and NO2) in para position of the salicyl moiety and their rhodium complexes showed good antiplasmodial activity against both the CQS-NF54 and the CQR-Dd2 strains. The crystal structures of (η(5)-pentamethylcyclopentadienyl){N(1)-(7-chloroquinolin-4-yl)-N(2)-(pyridin-2-ylmethyl)ethane-1,2-diamine)} chlororhodium(iii) chloride and (η(5)-pentamethylcyclopentadienyl){(4-chloro-2-(((2-((7-chloroquinolin-4-yl)amino)ethyl)imino)methyl)phenolate)}chlororhodium(iii) chloride are reported. The crystallization of the amino-pyridyl complex (η(5)-pentamethylcyclopentadienyl){(N(1)-(7-chloroquinolin-4-yl)-N(2)-(pyridin-2-ylmethyl)ethane-1,2-diamine)}chloroiridium(iii) chloride in acetone resulted in the formation of the imino-pyridyl derivative (η(5)-pentamethylcyclopentadienyl){(N1-(7-chloroquinolin-4-yl)-N2-(pyridin-2-ylmethylene)ethane-1,2-diamine)}chloroiridium(iii) chloride, the crystal structure of which is also reported.
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| 5. |
- Elding, Lars Ivar, et al.
(author)
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Detection of a Novel Intermediate in the Addition of Thiols to Osmium Carbonyl Clusters
- 1998
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In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 1998:24, s. 2721-2722
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Journal article (peer-reviewed)abstract
- Spectroscopic studies of the reaction of [Os-3(CO)(11)MeCN)] with para-thiocresol to form [Os-3(mu-H)(CO)(10)(mu-SC6H4Me-p)] indicate that the reaction proceeds via a two-step consecutive process involving the intermediate [Os-3(CO)(11)-(MeC6H4SH-p)], in which there is an agostic Os-H-S interaction.
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| 6. |
- King, Jason D, et al.
(author)
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Synthesis and Characterization of Diphenyl-2-thienylphosphine Derivatives
- 1999
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In: Journal of Organometallic Chemistry. - 0022-328X. ; 573:1-2, s. 272-278
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Journal article (peer-reviewed)abstract
- The reaction of [Co2{μ-C2(CO2Me)2}(CO)6] with the ligand diphenyl-2-thienylphosphine, PPh2(C4H3S), yields the complexes [Co2{μ-C2(CO2Me)2}(CO)5{PPh2(C4H3S)}] (1) and [Co2{μ-C2(CO2Me)2}(CO)4{PPh2(C4H3S)}2] (2). The related complex [Co3(μ3CMe)(CO)9] reacts with the same ligand to give [Co3(μ3-CMe)(CO)8{PPh2(C4H3S)}] (3) and [Co3(μ3-CMe)(CO)7{PPh2(C4H3S))2] (4). Thermolysis of 1 at 80°C leads to partial conversion of 1 into 2, which is isolated in low yield. Similarly, thermolysis of 3 at 70°C results in partial conversion of 3 to 4. Coordination of the thienyl unit of the diphenyl-2-thienylphosphine ligand to cobalt could not be detected in these thermolyses. Complexes 1–4 have been completely characterized and the crystal structure of complex 4 has been determined.
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| 7. |
- Kiriakidou-Kazemifar, Nitsa, et al.
(author)
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Synthesis and characterization of new thioether derivatives of [Os3(CO)12] and [H2Os3(CO)10]; crystal and molecular structures of [Os3(CO)11(L)] [Et2S, Pr2S, S(CH2)5] and [Os3(CO)9(m-H)(m-X){SMe(But)}] (X = H, OH)
- 2001
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In: Journal of Organometallic Chemistry. - 0022-328X. ; 623:1-2, s. 191-201
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Journal article (peer-reviewed)abstract
- Reaction of [Os3(CO)11(NCMe)] with R2S (R = Et, nPr) and MeSBut results in the formation of [Os3(CO)11(L)] (L = thioether) clusters in which the thioethers are coordinated in an equatorial site of the triosmium framework. Such monosubstituted clusters are also formed when [Os3(CO)10(NCMe)2] is reacted with R2S (R = Et, nPr) while reaction of the same cluster with Ph2S or MeSPh results in the formation of orthometalated clusters, viz. [Os3(m-H)(CO)10(m-h2-C6H4SR)] and [Os3(m-H)(CO)9(m3-C6H4SPh)]. The similar reaction of [Os3(m-H)2(CO)10] with Pr2S, MeSBut, MeSPh or Ph2S does not lead to discernable products except when carried out in the presence of trimethylamine N-oxide, which leads to clusters of the general formula [Os3(CO)9(m-H)2(thioether)]. The crystal and mol. structures of [Os3(CO)11(L)] (L = Et2S, Pr2S, S(CH2)5) and [Os3(CO)9(m-H)(m-X){SMe(But)}] (X = H, OH) are presented.
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| 8. |
- Moberg, Viktor, et al.
(author)
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Efficient Cluster-Based Catalysts for Asymmetric Hydrogenation of α-Unsaturated Carboxylic Acids.
- 2012
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In: Chemistry: A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 18:39, s. 12458-12478
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Journal article (peer-reviewed)abstract
- The new clusters [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)], [H(4) Ru(4) (CO)(10) (1,1-P-P)] and [H(4) Ru(4) (CO)(11) (P-P)] (P-P=chiral diphosphine of the ferrocene-based Josiphos or Walphos ligand families) have been synthesised and characterised. The crystal and molecular structures of eleven clusters reveal that the coordination modes of the diphosphine in the [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)] clusters are different for the Josiphos and the Walphos ligands. The Josiphos ligands bridge a metal-metal bond of the ruthenium tetrahedron in the "conventional" manner, that is, with both phosphine moieties coordinated in equatorial positions relative to a triangular face of the tetrahedron, whereas the phosphine moieties of the Walphos ligands coordinate in one axial and one equatorial position. The differences in the ligand size and the coordination mode between the two types of ligands appear to be reflected in a relative propensity for isomerisation; in solution, the [H(4) Ru(4) (CO)(10) (1,1-Walphos)] clusters isomerise to the corresponding [H(4) Ru(4) (CO)(10) (μ-1,2-Walphos)] clusters, whereas the Josiphos-containing clusters show no tendency to isomerisation in solution. The clusters have been tested as catalysts for asymmetric hydrogenation of four prochiral α-unsaturated carboxylic acids and the prochiral methyl ester (E)-methyl 2-methylbut-2-enoate. High conversion rates (>94 %) and selectivities of product formation were observed for almost all catalysts/catalyst precursors. The observed enantioselectivities were low or nonexistent for the Josiphos-containing clusters and catalyst (cluster) recovery was low, suggesting that cluster fragmentation takes place. On the other hand, excellent conversion rates (99-100 %), product selectivities (99-100 % in most cases) and good enantioselectivities, reaching 90 % enantiomeric excess (ee) in certain cases, were observed for the Walphos-containing clusters, and the clusters could be recovered in good yield after completed catalysis. Results from high-pressure NMR and IR studies, catalyst poisoning tests and comparison of catalytic properties of two [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)] clusters (P-P=Walphos ligands) with the analogous mononuclear catalysts [Ru(P-P)(carboxylato)(2) ] suggest that these clusters may be the active catalytic species, or direct precursors of an active catalytic cluster species.
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| 9. |
- Monari, Magda, et al.
(author)
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Synthesis of New Thiol Derivatives of Os3(CO)12; Crystal Structure of HOs3(CO)10(SBut)
- 1996
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In: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 247:1, s. 131-134
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Journal article (peer-reviewed)abstract
- The clusters [Os3(CO) 10(/z-H) {/z-SC(CH3)3} ] (1) and [Os3(CO) to(/z-H) {p-SCeHH } ] (2) have been synthesized by addition of the appropriate thiol RSH (R ffi C(CH3)3, CeHH) to [Os3(CO) it (NCMe) ] or [Os3(CO) io(NCMe)2] in dichloromethane. Clusters 1 and 2 have been characterized by 1R, NMR, mass speetromet~, and, in the case of 1, X-ray crystallography. Compound I crystallizes in space group P2~/n (affi9.507(1), bffi 12.860(1), cffi 17.838(3) A, flffi99.77(1) °, Zffi4). The molecule conforms to an idealized C, symmetry. The bond distances in the osmium triangle average 2.860 A; there is no significant elongation of the Os-Os edge in I that is bridged by the hydride and the thiolate moiety.
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| 10. |
- Persson, Roger, et al.
(author)
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Synthesis and Characterization of Triosmium Clusters Containing the Bidentate Ligand Ph2PCH2CH2SMe; Detection of an Unusual Isomerisation Reaction
- 2001
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In: Organometallics. - : American Chemical Society (ACS). - 1520-6041 .- 0276-7333. ; 20:20, s. 4150-4160
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Journal article (peer-reviewed)abstract
- Diphenylphosphinoethylene methyl sulfide, Ph2PCH2CH2SMe, reacts with [Os3(CO)11(NCMe)] yielding [Os3(CO)11(Ph2PCH2CH2SMe)]. Treatment of [Os3(CO)10(NCMe)2] with 1 equiv of the P,S ligand initially yields the cluster 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)], in which the phosphine and the thioether moieties coordinate to different metal atoms of the metal triangle; addition of two or more equivalents of the ligand yields 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)] and [Os3(CO)10(Ph2PCH2CH2SMe)2]. The cluster 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)] is metastable and undergoes a slow isomerization reaction at room temperature to form 1,1-[Os3(CO)10(Ph2PCH2CH2SMe)], in which the ligand chelates one Os atom. Computational modeling of 1,2- and 1,1-[Os3(CO)10(Ph2PCH2CH2SMe)] indicates that the two clusters are of similar stability, with the latter isomer being of slightly lower energy. The dynamic behavior of the clusters have been investigated by variable-temperature 13C{1H} and 31P{1H} NMR, and the kinetics of the isomerization reaction have been measured. The latter indicate that the isomerization proceeds via an associative mechanism which is proposed to involve an intramolecular nucleophilic attack by the coordinated sulfur on an osmium atom. The solid state structures of [Os3(CO)11(Ph2PCH2CH2SMe)], 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)], and 1,1-[Os3(CO)10(Ph2PCH2CH2SMe)] are reported.
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