Syntheses and fluxional processes of diphenyl(2-thienyl)phosphane derivatives of triosmium clusters

• 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.

Ämnesord

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

Nyckelord

hydrodesulfurisation

fluxionality

cluster

thienylphosphane

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