Reactions of [Os3(CO)10(μ-dppm)] and [HOs3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}] with Bu3GeH: Ge–H and Ge–C bond cleavage at triosmium centers

Abstract

The reactivity of the triosmium clusters [Os3(CO)10(μ-dppm)] [dppm = bis(diphenylphosphino)methane] and [HOs3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}] with tributylgermanium hydride (Bu3GeH) has been investigated. Oxidative addition of Bu3GeH to [Os3(CO)10(μ-dppm)] at 110 °C affords [HOs3(CO)9(GeBu3)(μ-dppm)] (1) which undergoes further decarbonylation upon prolonged heating to yield [H2Os3(CO)7(GeBu3){μ3-Ph2PCH2P(Ph)C6H4}] (2) and [HOs3(CO)8(GeBu3)(μ-GeBu2)(μ-dppm)] (3). Control experiments confirm the bimodal formation of 2 and 3 from 1 during thermolysis. Cluster 2 reacts with additional Bu3GeH at 140 °C to give [Os3(CO)6(μ-GeBu2)2{μ3-PhP(C6H4)CH2P(Ph)C6H4}] (4), a thermolysis product also produced from 3. In contrast, oxidative addition of Bu3GeH to [HOs3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}] occurs at room temperature to afford [H2Os3(CO)8(GeBu3){μ3-Ph2PCH2P(Ph)C6H4}] (5), which decarbonylates at 110 °C to yield 4. All new clusters have been characterized by elemental analyses and spectroscopic methods, and the molecular structures established by X-ray crystallography. Electronic structure calculations on the different hydride isomers based on 1 and 5 are reported.