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- Kiriakidou-Kazemifar, Nitsa, et al.
(författare)
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Syntheses and fluxional processes of diphenyl(2-thienyl)phosphane derivatives of triosmium clusters
- 2006
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1099-0682 .- 1434-1948. ; :10, s. 2058-2068
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Tidskriftsartikel (refereegranskat)abstract
- Thermal treatment of [OS3(CO)(12)] with diphenyl(2-thienyl)phosphane, Ph(2)p(C4H3S), results in the formation of [Os-3(CO)(12-x){Ph2P(C4H3S)}(x)] (x = 1-3, 1-3), but no C-H bond activation was observed. Reaction of [H2Os3(CO)(10)] with diphenyl(2-thienyl)phosphane at ambient temperature affords [HOs3(mu-H)(CO)(10){Ph2P(C4H3S}] (4), but when the same reaction is repeated at elevated temperatures, the cyclometallated species [(mu-H)Os-3(CO)(9){mu(3)-Ph(2)p(C4H2S)}] (5) and [mu-H) Os-3(CO)(8){mu 3-Ph2P(C4H2S)}(Ph2P(C4H3S)}] (6) are formed. In addition, two more products, tentatively assigned as [(mu-H)Os-3(CO)(6()mu(3)-Ph2P(C4H2S)}{mu-Ph2P(C4H3S)}{Ph2P-(C4H3S)}] (7) and [(mu-H)Os-3 (CO)(7) {mu-Ph2P(C4H2S)}] (4)tPh(2)P(C(4)H3(S)))(Ph2P(C4H3S))] (8) are obtained. The dynamic behaviours of 2, 5 and 6 have been studied by variable-temperature (VT) and H-1 P-31{H-1} NMR spectroscopy. The VT P-31{H-1} NMR spectra of [Os-3(CO)(10){Ph2P(C4H3S)}(2)] (2) demonstrate that a mixture of two isomers, which are in rapid exchange at room temperature, is present and that the less common cis-trans isomer, whose structure has been determined by X-ray crystallography, is favoured for this cluster. The VT H-1 NMR spectra of 5 indicate the presence of two isomers which are proposed to arise from an oscillation of the sigma,eta(2)-vinyl group of the thienyl moiety between two metal atoms. A similar fluxional process is proposed to occur in 6 and the assignment of the room-temperature structure(s) of this cluster was confirmed by H-1-Os-187 2D HMQC spectroscopy. In addition to 2, the solid-state structures of 3, 5 and 6 have been determined by X-ray crystallography. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006.
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| 2. |
- Stchedroff, MJ, et al.
(författare)
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Synthesis, characterisation and natural abundance Os-187 NMR spectroscopy of hydride bridged triosmium clusters with chiral diphosphine ligands
- 2006
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 359:3, s. 926-937
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of [Os-3(mu-H)(2)(CO)(10)] with the chiral diphosphines BINAP, tolBINAP [(R)-2,2'-bis(di-4-tolylphosphino)-1,1'-binaphthyl], DIOP [(4R,5R)-(-)-O-isopropenylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino) butane] affords [Os-3(mu-H)(2)(CO)(8)(mu-L)] (L = BINAP (1), tolBINAP (2), DIOP (4)) in high yield. The X-ray structures for 1, 2 and 4 are reported, and structural and spectroscopic comparisons are made between these clusters and [Os-3(mu-H)(2)(CO)(8)(mu-L)] (L = dppm (5), dppe (6), dppp (7)) which were synthesised similarly. Compounds 5 to 7 were previously synthesised by hydrogenation of 1,2-[OS3(CO)(10)(mu-L)] but the route from [Os(mu-H)(2)(CO)(10)] is preferable. The H-bridged Os center dot center dot Os distances are similar in 1, 2 and 4 indicating that these species are formally unsaturated 46-electron clusters. The P center dot center dot center dot P distances vary from 4.24 to 4.30 angstrom in 1 and 2, respectively, to 4.53 angstrom in 4 and there are related changes in the angles associated with the ligand set around the H-bridged osmium atoms. Introduction of the diphosphine ligands completely suppresses the ability to add CO, to insert acetylene to form a mu-eta(1), eta(2)-vinyl compound, and to exchange hydride ligands with styrene-d(8), which are reactions characteristic of [Os-3(mu-H)(2)(CO)(10)], Clusters 2 and 5-7 were also used to examine the potential of natural abundance Os-187 NMR spectroscopy through techniques based on inverse detection by HMQC, HSQC and HMBC spectroscopy. (c) 2005 Elsevier B.V. All rights reserved.
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