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)tBu (R2bzam = N,N′-disubstituted benzamidinate) was studied for R = tBu (1tBu) and iPr (1iPr). The mono-, bi-, and/or trinuclear derivatives [Ru­(1R)­(CO)4], [Ru­(1R)2­(CO)3], [Ru2(1iPr)­(CO)7], [Ru3(1tBu)­(CO)11], [Ru3(1tBu)2­(CO)10], and [Ru3(1R)3­(CO)9] (R = tBu, iPr) 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(1R)­(CO)11], and [Ru3(1R)2­(CO)10] form an adduct with the germylene 1R 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 1R with [Ru­(1R)­(CO)4] or [Ru3(1R)3­(CO)9], which both give [Ru­(1R)2­(CO)3], or the reactions of [Ru­(1tBu)­(CO)4] and [Ru­(1iPr)­(CO)4] with [Ru3(CO)12], which give [Ru3(1tBu)­(CO)11] and [Ru2(1iPr)­(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.