Syntheses and Fluxional Processes of Diphenyl(2‐thienyl)phosphane Derivatives of Triosmium Clusters

Abstract

Thermal treatment of [Os3(CO)12] with diphenyl(2‐thienyl)phosphane, Ph2P(C4H3S), results in the formation of [Os3(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(μ‐H)(CO)10{Ph2P(C4H3S)}] (4), but when the samereaction is repeated at elevated temperatures, the cyclometallated species [(μ‐H)Os3(CO)9{μ3‐Ph2P(C4H2S)}] (5) and[(μ‐H)Os3(CO)8{μ3‐Ph2P(C4H2S)}{Ph2P(C4H3S)}] (6) are formed. In addition, two more products, tentatively assigned as [(μ‐H)Os3(CO)6{μ3‐Ph2P(C4H2S)}{μ‐Ph2P(C4H3S)}{Ph2P(C4H3S)}] (7) and [(μ‐H)Os3(CO)7{μ‐Ph2P(C4H2S)}{μ‐Ph2P(C4H3S)}{Ph2P(C4H3S)}] (8) are obtained. The dynamic behaviours of 2, 5 and 6 have been studied by variable‐temperature (VT) 1H and 31P{1H} NMR spectroscopy. The VT 31P{1H} NMR spectra of [Os3(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 1H NMR spectra of 5 indicate the presence of two isomers which are proposed to arise from an oscillation of the σ,η2‐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 1H‐187Os 2D HMQC spectroscopy. In addition to 2, the solid‐state structures of 3, 5 and 6 have been determined by X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Two modes of C–H bond activation of tris(2-thienyl)phosphine in trinuclear osmium carbonyl clusters

“…Furthermore, Vahrenkamp et al [13] have demonstrated that the tris(2-thienyl)phosphine substituted compounds [Ru 3 (CO) 10 {P(C 4 H 3 S) 3 } 2 ] and [Ru(CO) 3 {P(C 4 H 3 S) 3 } 2 ] can be prepared from the ketyl initiated reaction between [Ru 3 (CO) 12 ] and tris(2-thienyl)phosphine. As a part of our studies of the reactivity of triosmium clusters with phosphothiophenes, we report here the reactions of [Os 3 (CO) 12 ] and [Os 3 (l-H) 2 (CO) 10 ] with tris(2-thienyl)phosphine.…”

“…Thus, we recently reported that [Os 3 (CO) 12 ] and [Os 3 (l-H) 2 -(CO) 10 ] react with diphenyl-2-thienylphosphine to give substitution products with the ligand coordinated in monoand bidentate coordination modes via its phosphorus and sulfur atoms and, in addition, C-H cleavage at the thienyl ring of the ligand [12]. Furthermore, Vahrenkamp et al [13] have demonstrated that the tris(2-thienyl)phosphine substituted compounds [Ru 3 (CO) 10 {P(C 4 H 3 S) 3 } 2 ] and [Ru(CO) 3 {P(C 4 H 3 S) 3 } 2 ] can be prepared from the ketyl initiated reaction between [Ru 3 (CO) 12 ] and tris(2-thienyl)phosphine. As a part of our studies of the reactivity of triosmium clusters with phosphothiophenes, we report here the reactions of [Os 3 (CO) 12 ] and [Os 3 (l-H) 2 (CO) 10 ] with tris(2-thienyl)phosphine.…”

“…We have shown that the reaction of diphenyl-2-thienylphosphine with [Ru 3 (CO) 12 ] gives [Ru 3 (l-H)(l 3 -Ph 2 PC 4 H 2 S)-( CO) 9 ], [Ru 3 (l-H)(l 3 -Ph 2 PC 4 H 2 S)(CO) 8 (Ph 2 PC 4 H 3 S)], [Ru 4 (l 4 -PPh)(l 4 -C 4 H 4 )(CO) 11 ] and [Ru 4 (l 4 -PPh)(l 4 -C 4 H 2 S)(CO) 11 ] via cyclometallation and P-C bond cleavage of the ligand [11]. In order to compare the reactivities of the ruthenium clusters with their osmium homologues, we have extended this work to triosmium clusters.…”

“…One of the earliest reports of the interaction of thiophene with organometallic compounds described the desulfurization of the heterocycle by [Fe 3 (CO) 12 ] [2,3]. Rauchfuss and coworkers [4] demonstrated that thiaferroles are easily converted to the corresponding ferroles and they established that insertion of an iron atom into a C-S bond clearly activates the heterocycle towards desulfurization.…”

“…Rauchfuss and coworkers [4] demonstrated that thiaferroles are easily converted to the corresponding ferroles and they established that insertion of an iron atom into a C-S bond clearly activates the heterocycle towards desulfurization. The reaction of [Ru 3 (CO) 12 ] with thiophene proceeds similarly via C-S cleavage giving [Ru 2 (l-C 4 H 4 )(CO) 6 ] and [Ru 4 (l 3 -S)(l-C 4 H 4 )(CO) 11 ] [5]. It has been demonstrated that C-H bond activation predominates over C-S cleavage when thiophene reacts with [Os 3 (CO) 12 ] and [Os 3 (CO) 10 benzothiophene when coordinated to a triosmium cluster [Os 3 (l 3 -S)(l-C 8 H 5 S)(CO ) 10 ] has been reported to give [Os 3 (l-C 8 H 6 S)( CO) 10 ] which contains an open benzothiophene ligand coordinated to an open Os 3 unit through a l-S and l-g 2 -vinyl group [7,8].…”