Multifaceted Chemistry of [(Cymene)RuCl₂]₂ and PCy₃

The reaction of [(cymene)RuCl2]2 (1) with PCy3 was investigated using different stoichiometries and reaction conditions. Whereas a mixture of complex 1 and 2 equiv of PCy3 in methanol gave the known adduct [(cymene)RuCl2(PCy3)] (2), the utilization of 4 equiv gave the hydrido complex [(cymene)RuHCl(PCy3)] (3) along with the phosphonium salt [PCy3(CH2OH)]Cl (4). Prolonged heating of 1 and 4 equiv of PCy3 in methanol under argon resulted in the formation of complex [RuHCl(CO)(PCy3)2] (5). Dinuclear, chloro-bridged complexes were generated when 1 was reacted with only 1 equiv of PCy3. In a mixture of THF and allyl alcohol, the carbonyl complex [(cymene)Ru(μ-Cl)3RuCl(CO)(PCy3)] (6) was formed. In dioxane, however, intramolecular C−H activation of the PCy3 ligand was observed, resulting in the formation of [(cymene)Ru(μ-Cl)3RuCl{PCy2(C6H9)}] (7). When the reaction was performed under an atmosphere of H2, the dihydrogen complex [(cymene)Ru(μ-Cl)3RuCl(H2)(PCy3)] (8) could be isolated. An inert trinuclear cluster of the formula [RuCl2(PCy3)]3 (10) was formed when 1 was heated with 2 equiv of PCy3 in THF. The complexes 3, 6, 7, 8, and 10 as well as the phosphonium salt 4 were characterized by single-crystal X-ray analysis.