Novel triruthenium polyhydrido complexes having triply bridging alkylzinc ligands, {Cp‘Ru(μ-H)}3(μ3-ZnR)(μ3-H) (3a: R = Me, 3b: R = Et) and {Cp‘Ru(μ-H)}3(μ3-ZnEt)2 (4a: R = Me, 4b: R = Et), are obtained by the reaction of {Cp‘Ru(μ-H)}3(μ3-H)2 (2) with a stoichiometric amount of the corresponding dialkylzinc ZnR2. X-ray diffraction studies of 3b and 4a display the structural identity of those that have a triply bridging alkylzinc ligand. The X-ray studies as well as 1H NMR spectroscopy reveal the existence of bonding interactions between the μ3-zinc and the Ru-bound hydrido ligands in 3 and 4. In the variable-temperature 1H NMR study of 3b, activation parameters, ΔS⧧ and ΔH⧧, for the coordination-site exchange process among the hydrido ligands were estimated at −1.5 ± 1.3 cal mol-1 K-1 and 15.0 ± 0.4 kcal mol-1, respectively. The reaction of a diruthenium tetrahydrido complex, (Cp‘Ru)2(μ-H)4 (1), with an equimolar amount of dialkylzinc yields (Cp‘Ru)2(μ-ZnR)(μ-H)3 (5a: R = Me, 5b: R = Et). Di-μ-alkyl...
Read full abstract