Displacement of phenyl and styryl ligands by benzophenone imine and 2-vinylpyridine on ruthenium and osmium

Abstract

The phenyl complexes MPhCl(CO)(PiPr3)2 (M = Ru (3), Os (4)) have been prepared by reaction of MHCl(CO)(PiPr3)2 (M = Ru (1), Os (2)) with HgPh2. In solution the phenyl ligand of these compounds rotates around the M−Ph bond. The activation parameters for the process are ΔH = 13.0 ± 0.6 kcal·mol-1 and ΔS = 1.5 ± 1.3 cal·mol-1·K-1 for 3 and ΔH = 11.7 ± 0.5 kcal·mol-1 and ΔS = −5.4 ± 1.2 cal·mol-1·K-1 for 4. The addition of benzophenone imine to dichloromethane solutions of 3 and 4 and the related styryl complexes M{(E)-CHCHPh}Cl(CO)(PiPr3)2 (M = Ru (7), Os (8)) leads to equilibrium mixtures between the starting compounds and the six-coordinate derivatives MPhCl(NHCPh2)(CO)(PiPr3)2 (M = Ru (5): ΔH° = −8.6 ± 0.4 kcal·mol-1, ΔS° = −42.5 ± 1.6 cal·mol-1·K-1; M = Os (6): ΔH° = −9.1 ± 0.8 kcal·mol-1, ΔS° = −31.0 ± 2.6 cal·mol-1·K-1) and M{(E)-CHCHPh}Cl(NHCPh2)(CO)(PiPr3)2 (M = Ru (9): ΔH° = −9.5 ± 0.3 kcal·mol-1, ΔS° = −39.4 ± 1.1 cal·mol-1·K-1; M = Os (10): ΔH° = −8.8 ± 0.8 kcal·mol-1, ΔS° = −27.3 ± 2.6 cal·mol-1·K-1). In toluene under reflux complexes 3, 4, 7, and 8 react with benzophenone imine and 2-vinylpyridine to afford the metalated derivatives (M = Ru (11), Os (12)) and (M = Ru (13), Os (14)), releasing benzene and styrene. Complexes 9, 12, and 13 have been characterized by X-ray diffraction analysis. The structure of 9 shows a Cl···H−N hydrogen bond (2.47 Å) between the NH hydrogen atom of the imine and the chloride ligand.