B.V. It incorporates referee's comments but changes resulting from the publishing process, such a... more B.V. It incorporates referee's comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document.
The heteronuclear cobalt-platinum cluster [Co 2 Pt 2 (IPr) 2 (µ 2 -CO) 4 (CO) 4 ] can be obtained... more The heteronuclear cobalt-platinum cluster [Co 2 Pt 2 (IPr) 2 (µ 2 -CO) 4 (CO) 4 ] can be obtained through an addition reaction in [Co 2 (CO) 8 ], and with subsequent cluster fragmentation in [Co 4 (CO) 12 ] and [Co 3 (µ 3 -CH)(CO) 9 ], upon reaction with the [Pt(IPr)] fragment. The last reaction also afforded another cobaltplatinum cluster [Co 4 Pt 2 (µ 6 -C)(IPr) 2 (µ 2 -CO) 5 (CO) 6 ]. These are the first examples of Co-Pt heteronuclear clusters containing NHC ligands.
Very strong trans effect in ruthenacyclic carbamoyl complexes leads to ligand redistribution in p... more Very strong trans effect in ruthenacyclic carbamoyl complexes leads to ligand redistribution in phosphine derivatives
A set of metal carbonyl cluster-boronic acid conjugates of the group VIII metals (Fe, Ru, and Os)... more A set of metal carbonyl cluster-boronic acid conjugates of the group VIII metals (Fe, Ru, and Os) were synthesized and their antiproliferative effects measured against two breast cancer cell lines (MCF-7 and MDA-MB-231) and a noncancerous breast epithelial (MCF-10A) cell line. The cytotoxicity followed the order Ru > Os > Fe for the MDA-MB-231 cells, although the latter two exhibited similar cytotoxicity against MCF-7 and MCF-10A cells. The osmium species {Os 3 (CO) 10 (μ-H)[μ-SC 6 H 4 -p-B(OH) 2 ]} (2) could be chemically oxidized to its hydroxy analogue [Os 3 (CO) 10 (μ-H)(μ-SC 6 H 4 -p-OH)] (2-OH), which showed comparable cytotoxicity. Mode of action studies pointed to an apoptotic pathway for cell death.
Y. (2013). Reactions of Cp*Ir(CO)2 with pentafluorobenzonitrile: Half-sandwich iridium complexes ... more Y. (2013). Reactions of Cp*Ir(CO)2 with pentafluorobenzonitrile: Half-sandwich iridium complexes Cp*Ir(CO)(p-C6F4CN)(X).
Monostibine-protected ionic Au 13 nanoclusters, namely, [Au 13 (L) 8 (Cl) 4 ][Cl] (L¼ SbPh 3 , 2a... more Monostibine-protected ionic Au 13 nanoclusters, namely, [Au 13 (L) 8 (Cl) 4 ][Cl] (L¼ SbPh 3 , 2a$Cl; Sb(p-tolyl) 3 , 2b$Cl) were prepared by the direct reduction of Au(L)Cl with NaBH 4 in dichloromethane. Anion exchange with 2a$Cl afforded [Au 13 (SbPh 3 ) 8 (Cl) 4 ][X] (X ¼ PF 6 , 2a$PF 6 ; BPh 4 , 2a$BPh 4 ). All these have been characterized by multinuclear NMR, ESI-MS and UV-Vis spectroscopy. Crystallographic analysis of 2a$BPh 4 reveals that the cation possesses C 2v symmetry and the tridecagold core adopts a closed icosahedron configuration. The weaker coordinating ability of the stibine ligands leads to the ready reaction of 2b$Cl with PPh 3 or glutathione (GSH) to form the smaller phosphine-protected cluster [Au 11 (PPh 3 ) 8 Cl 2 ][Cl] or larger thiolate-protected cluster Au 25 (SG) 18 , respectively. In the latter reaction, the addition of a small amount (0.5 to 3.5 equivalents) of a suitable oxidant such as K 3 (Fe(CN) 6 accelerates the conversion rate significantly.
Society. It incorporates referee's comments but changes resulting from the publishing process, su... more Society. It incorporates referee's comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document.
A set of structural mimics of the [Fe]-hydrogenase active site comprising all the group VIII meta... more A set of structural mimics of the [Fe]-hydrogenase active site comprising all the group VIII metals, viz., [M(2-NHC(O)C5H4N)(CO)2(2-S-C5H4N)], has been synthesized. They exist as a mixture of isomers in solution, and the relative stability of the isomers depends on the nature of the metal and the substituent at the 6-position of the pyridine ligand.
The metallostibine Os2(CO)8(-SbPh), 2, acts as a good two-electron donor ligand, reacting readil... more The metallostibine Os2(CO)8(-SbPh), 2, acts as a good two-electron donor ligand, reacting readily with Group 8 metal carbonyls to give heterometallic clusters. Specifically, it undergoes ligand substitution reaction with Fe2(CO)9, Os3(CO)11(CH3CN), or Os3(CO)10(CH3CN)2 to afford Os2Fe(CO)12(3-SbPh), 3, Os5(CO)19(3-SbPh), 4, or Os7(CO)26(3-SbPh)2, 5, respectively, in moderate to high yields. An analogous reaction with Ru3(CO)11(CH3CN) afforded another spirocyclic cluster Os3Ru(CO)14(-PhCO)(4-Sb), 9. UV irradiation of 4 afforded the spirocyclic clusters Os5(CO)18(, 2 -PhCO)(4-Sb), 6, and Os5(CO)18(, 2 -C6H4)(-H)(4-Sb), 7, while the raft-like cluster Os5(CO)19(3-SbPh), 8, was obtained when a methanolic solution was exposed to natural light; cluster 5 failed to react under similar conditions. All the new clusters have been characterized spectroscopically and crystallographically, and possible pathways for the formation of 6-9 proposed.
European Journal of Inorganic Chemistry, Mar 28, 2019
The room temperature reaction of [Os3(CO)12] (1) with three molar equivalents of [PtCl(allyl)(NHC... more The room temperature reaction of [Os3(CO)12] (1) with three molar equivalents of [PtCl(allyl)(NHC)] (2) in the presence of KO t Bu afforded the heterometallic clusters [PtOs3(CO)12(NHC)] (3), [Pt2Os3(CO)12(NHC)2] (4) and [Pt3Os3(CO)12(NHC)3] ( ), together with a trace amount of the tetraosmium cluster [Os4(CO)10(µ-H)2(NHC)] ( ). The reaction pathway is thus similar to that for Pd analogues, with the exception of cluster 6. Unlike their Pd analogues, however, these clusters do not appear to readily interconvert. With a valence electron count of 58, the clusters 6 are deficient by four electrons.
Society. It incorporates referee's comments but changes resulting from the publishing process, su... more Society. It incorporates referee's comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document.
We describe the synthesis of the ruthenacyclic carbamoyl complexes [Ru(2-NHC(O)C 5 H 3 NMe)(CO) 2... more We describe the synthesis of the ruthenacyclic carbamoyl complexes [Ru(2-NHC(O)C 5 H 3 NMe)(CO) 2 (o,o-Me 2 -C 6 H 3 S)(L)] (L = H 2 O or MeCN), which have a labile water or acetonitrile ligand at their sixth coordination sites. Steric bulk around the ruthenium center is essential in preventing isomerization and dimerization, and embedding within papain can be achieved via coordination of its sole free cysteine residue. The observed chemistry parallels that of the natural [Fe]hydrogenase.
European Journal of Inorganic Chemistry, Nov 29, 2018
The ruthenacyclic carbamoyl complexes [RuX(2-NHC(O)C5H3NR)(CO)2(NCMe)] (R = H and Me; X = Br and ... more The ruthenacyclic carbamoyl complexes [RuX(2-NHC(O)C5H3NR)(CO)2(NCMe)] (R = H and Me; X = Br and SC6H3-o,o-Me2) are excellent catalysts for the hydrolysis of organosilanes, particularly towards primary silanes, generating hydrogen under ambient conditions within seconds. These complexes are structural mimics of the [Fe]-hydrogenase active site and like the natural enzyme, a labile ligand at the sixth coordination site is essential to the catalytic activity.
A stibine-stabilised gold nanocluster which acts as a homogeneous catalyst in the A3 coupling rea... more A stibine-stabilised gold nanocluster which acts as a homogeneous catalyst in the A3 coupling reaction.
The activated cluster Os3(CO)10(CH3CN)2 (1) reacts readily with a number of carboxylated chalcone... more The activated cluster Os3(CO)10(CH3CN)2 (1) reacts readily with a number of carboxylated chalcones and benzaldehydes (2a-j) to afford products with the general formula Os3(CO)10(µ-H)(µ-O2CR) (3a-j). The structures of all the novel clusters have been characterized by IR and 1 H NMR spectroscopy, as well as mass spectrometry and elemental analysis. Single-crystal X-ray diffraction analysis has also been carried out for one of the carboxylated chalcones and two of the derivatized clusters. The activity of some of the derivatized clusters against the ER+ breast carcinoma MCF-7 cancer cell line has also been evaluated.
The high nuclearity osmium carbonyl cluster Na2[Os10(μ6-C)(CO)24] is a good near-IR photoacoustic... more The high nuclearity osmium carbonyl cluster Na2[Os10(μ6-C)(CO)24] is a good near-IR photoacoustic contrast agent for full body imaging.
B.V. It incorporates referee's comments but changes resulting from the publishing process, such a... more B.V. It incorporates referee's comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document.
The heteronuclear cobalt-platinum cluster [Co 2 Pt 2 (IPr) 2 (µ 2 -CO) 4 (CO) 4 ] can be obtained... more The heteronuclear cobalt-platinum cluster [Co 2 Pt 2 (IPr) 2 (µ 2 -CO) 4 (CO) 4 ] can be obtained through an addition reaction in [Co 2 (CO) 8 ], and with subsequent cluster fragmentation in [Co 4 (CO) 12 ] and [Co 3 (µ 3 -CH)(CO) 9 ], upon reaction with the [Pt(IPr)] fragment. The last reaction also afforded another cobaltplatinum cluster [Co 4 Pt 2 (µ 6 -C)(IPr) 2 (µ 2 -CO) 5 (CO) 6 ]. These are the first examples of Co-Pt heteronuclear clusters containing NHC ligands.
Very strong trans effect in ruthenacyclic carbamoyl complexes leads to ligand redistribution in p... more Very strong trans effect in ruthenacyclic carbamoyl complexes leads to ligand redistribution in phosphine derivatives
A set of metal carbonyl cluster-boronic acid conjugates of the group VIII metals (Fe, Ru, and Os)... more A set of metal carbonyl cluster-boronic acid conjugates of the group VIII metals (Fe, Ru, and Os) were synthesized and their antiproliferative effects measured against two breast cancer cell lines (MCF-7 and MDA-MB-231) and a noncancerous breast epithelial (MCF-10A) cell line. The cytotoxicity followed the order Ru > Os > Fe for the MDA-MB-231 cells, although the latter two exhibited similar cytotoxicity against MCF-7 and MCF-10A cells. The osmium species {Os 3 (CO) 10 (μ-H)[μ-SC 6 H 4 -p-B(OH) 2 ]} (2) could be chemically oxidized to its hydroxy analogue [Os 3 (CO) 10 (μ-H)(μ-SC 6 H 4 -p-OH)] (2-OH), which showed comparable cytotoxicity. Mode of action studies pointed to an apoptotic pathway for cell death.
Y. (2013). Reactions of Cp*Ir(CO)2 with pentafluorobenzonitrile: Half-sandwich iridium complexes ... more Y. (2013). Reactions of Cp*Ir(CO)2 with pentafluorobenzonitrile: Half-sandwich iridium complexes Cp*Ir(CO)(p-C6F4CN)(X).
Monostibine-protected ionic Au 13 nanoclusters, namely, [Au 13 (L) 8 (Cl) 4 ][Cl] (L¼ SbPh 3 , 2a... more Monostibine-protected ionic Au 13 nanoclusters, namely, [Au 13 (L) 8 (Cl) 4 ][Cl] (L¼ SbPh 3 , 2a$Cl; Sb(p-tolyl) 3 , 2b$Cl) were prepared by the direct reduction of Au(L)Cl with NaBH 4 in dichloromethane. Anion exchange with 2a$Cl afforded [Au 13 (SbPh 3 ) 8 (Cl) 4 ][X] (X ¼ PF 6 , 2a$PF 6 ; BPh 4 , 2a$BPh 4 ). All these have been characterized by multinuclear NMR, ESI-MS and UV-Vis spectroscopy. Crystallographic analysis of 2a$BPh 4 reveals that the cation possesses C 2v symmetry and the tridecagold core adopts a closed icosahedron configuration. The weaker coordinating ability of the stibine ligands leads to the ready reaction of 2b$Cl with PPh 3 or glutathione (GSH) to form the smaller phosphine-protected cluster [Au 11 (PPh 3 ) 8 Cl 2 ][Cl] or larger thiolate-protected cluster Au 25 (SG) 18 , respectively. In the latter reaction, the addition of a small amount (0.5 to 3.5 equivalents) of a suitable oxidant such as K 3 (Fe(CN) 6 accelerates the conversion rate significantly.
Society. It incorporates referee's comments but changes resulting from the publishing process, su... more Society. It incorporates referee's comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document.
A set of structural mimics of the [Fe]-hydrogenase active site comprising all the group VIII meta... more A set of structural mimics of the [Fe]-hydrogenase active site comprising all the group VIII metals, viz., [M(2-NHC(O)C5H4N)(CO)2(2-S-C5H4N)], has been synthesized. They exist as a mixture of isomers in solution, and the relative stability of the isomers depends on the nature of the metal and the substituent at the 6-position of the pyridine ligand.
The metallostibine Os2(CO)8(-SbPh), 2, acts as a good two-electron donor ligand, reacting readil... more The metallostibine Os2(CO)8(-SbPh), 2, acts as a good two-electron donor ligand, reacting readily with Group 8 metal carbonyls to give heterometallic clusters. Specifically, it undergoes ligand substitution reaction with Fe2(CO)9, Os3(CO)11(CH3CN), or Os3(CO)10(CH3CN)2 to afford Os2Fe(CO)12(3-SbPh), 3, Os5(CO)19(3-SbPh), 4, or Os7(CO)26(3-SbPh)2, 5, respectively, in moderate to high yields. An analogous reaction with Ru3(CO)11(CH3CN) afforded another spirocyclic cluster Os3Ru(CO)14(-PhCO)(4-Sb), 9. UV irradiation of 4 afforded the spirocyclic clusters Os5(CO)18(, 2 -PhCO)(4-Sb), 6, and Os5(CO)18(, 2 -C6H4)(-H)(4-Sb), 7, while the raft-like cluster Os5(CO)19(3-SbPh), 8, was obtained when a methanolic solution was exposed to natural light; cluster 5 failed to react under similar conditions. All the new clusters have been characterized spectroscopically and crystallographically, and possible pathways for the formation of 6-9 proposed.
European Journal of Inorganic Chemistry, Mar 28, 2019
The room temperature reaction of [Os3(CO)12] (1) with three molar equivalents of [PtCl(allyl)(NHC... more The room temperature reaction of [Os3(CO)12] (1) with three molar equivalents of [PtCl(allyl)(NHC)] (2) in the presence of KO t Bu afforded the heterometallic clusters [PtOs3(CO)12(NHC)] (3), [Pt2Os3(CO)12(NHC)2] (4) and [Pt3Os3(CO)12(NHC)3] ( ), together with a trace amount of the tetraosmium cluster [Os4(CO)10(µ-H)2(NHC)] ( ). The reaction pathway is thus similar to that for Pd analogues, with the exception of cluster 6. Unlike their Pd analogues, however, these clusters do not appear to readily interconvert. With a valence electron count of 58, the clusters 6 are deficient by four electrons.
Society. It incorporates referee's comments but changes resulting from the publishing process, su... more Society. It incorporates referee's comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document.
We describe the synthesis of the ruthenacyclic carbamoyl complexes [Ru(2-NHC(O)C 5 H 3 NMe)(CO) 2... more We describe the synthesis of the ruthenacyclic carbamoyl complexes [Ru(2-NHC(O)C 5 H 3 NMe)(CO) 2 (o,o-Me 2 -C 6 H 3 S)(L)] (L = H 2 O or MeCN), which have a labile water or acetonitrile ligand at their sixth coordination sites. Steric bulk around the ruthenium center is essential in preventing isomerization and dimerization, and embedding within papain can be achieved via coordination of its sole free cysteine residue. The observed chemistry parallels that of the natural [Fe]hydrogenase.
European Journal of Inorganic Chemistry, Nov 29, 2018
The ruthenacyclic carbamoyl complexes [RuX(2-NHC(O)C5H3NR)(CO)2(NCMe)] (R = H and Me; X = Br and ... more The ruthenacyclic carbamoyl complexes [RuX(2-NHC(O)C5H3NR)(CO)2(NCMe)] (R = H and Me; X = Br and SC6H3-o,o-Me2) are excellent catalysts for the hydrolysis of organosilanes, particularly towards primary silanes, generating hydrogen under ambient conditions within seconds. These complexes are structural mimics of the [Fe]-hydrogenase active site and like the natural enzyme, a labile ligand at the sixth coordination site is essential to the catalytic activity.
A stibine-stabilised gold nanocluster which acts as a homogeneous catalyst in the A3 coupling rea... more A stibine-stabilised gold nanocluster which acts as a homogeneous catalyst in the A3 coupling reaction.
The activated cluster Os3(CO)10(CH3CN)2 (1) reacts readily with a number of carboxylated chalcone... more The activated cluster Os3(CO)10(CH3CN)2 (1) reacts readily with a number of carboxylated chalcones and benzaldehydes (2a-j) to afford products with the general formula Os3(CO)10(µ-H)(µ-O2CR) (3a-j). The structures of all the novel clusters have been characterized by IR and 1 H NMR spectroscopy, as well as mass spectrometry and elemental analysis. Single-crystal X-ray diffraction analysis has also been carried out for one of the carboxylated chalcones and two of the derivatized clusters. The activity of some of the derivatized clusters against the ER+ breast carcinoma MCF-7 cancer cell line has also been evaluated.
The high nuclearity osmium carbonyl cluster Na2[Os10(μ6-C)(CO)24] is a good near-IR photoacoustic... more The high nuclearity osmium carbonyl cluster Na2[Os10(μ6-C)(CO)24] is a good near-IR photoacoustic contrast agent for full body imaging.
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