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(R(2)bzam)Bu-t (R(2)bzam = N,N'-disubstituted benzamidinate) was studied for R = Bu-t (1(tBu)) and Pr-i (1(iPr)). The mono-, bi-, and/or trinuclear derivatives [Ru(1(R))(CO)(4)] [Ru(1(R))(2)(CO)(3)], [Ru-2(1(iPr))(CO)(7)] [Ru-3(1(tBu))(CO)(11)], [Ru-3(1(tBu)),(CO)(10)], and [Ru-3(1(R))(3)(CO)(9)] (R = Bu-t, Pr-i) 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 [Ru-3(CO)(12)], [Ru-3(1(R))(CO)(11)], and [Ru-3(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 degrees C, additional processes are also possible, such as the reactions of 1(R) with [Ru(1(R))(CO)(4)] or [Ru-3(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 [Ru-3(CO)(12)], which give [Ru-3(1(tBu))(CO)(11)] and [Ru-2(1(iPr))(CO)(7)], respectively. This wide reaction panorama helps rationalize previously reported outcomes of reactions of [Ru-3(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.