Amidinatogermylene Derivatives of Ruthenium Carbonyl: New Insights into the Reactivity of [Ru3(CO)12] with Two-Electron-Donor Reagents of High Basicity

The reactivity of ruthenium carbonyl with amidinatogermylenes of the type Ge(R2bzam) t Bu (R2bzam = N,N′-disubstituted benzamidinate) was studied for R = t Bu (1 tBu ) and i Pr (1 iPr ). The mono-, bi-, and/or trinuclear derivatives [Ru(1 R )­(CO)4], [Ru(1 R )2­(CO)3], [Ru2(1 iPr )­(CO)7], [Ru3(1 tBu )­(CO)11], [Ru3(1 tBu )2­(CO)10], and [Ru3(1 R )3­(CO)9] (R = t Bu, i Pr) were isolated in yields that depend upon the reactant ratio and the reaction temperature. The experimental data are consistent with the proposal that, at room temperature, the trinuclear complexes [Ru3­(CO)12], [Ru3(1 R )­(CO)11], and [Ru3(1 R )2­(CO)10] form an adduct with the germylene 1 R that may evolve through two different reaction pathways, (a) releasing a CO ligand (thus leading to the corresponding trinuclear CO-substituted product) and/or (b) cleaving the cluster framework (thus leading to mononuclear germylene-containing products). At 90 °C, additional processes are also possible, such as the reactions of 1 R with [Ru(1 R )­(CO)4] or [Ru3(1 R )3­(CO)9], which both give [Ru(1 R )2­(CO)3], or the reactions of [Ru(1 tBu )­(CO)4] and [Ru(1 iPr )­(CO)4] with [Ru3(CO)12], which give [Ru3(1 tBu )­(CO)11] and [Ru2(1 iPr )­(CO)7], respectively. This wide reaction panorama helps rationalize previously reported outcomes of reactions of [Ru3(CO)12] with other reagents of high basicity, such as trialkylphosphines or N-heterocyclic carbenes, including results for which no satisfactory explanation has been hitherto provided.