Synthesis and unexpected reactivity of [Ru(η 6-cymene)Cl2(PPh2Cl)], leading to [Ru(η 6-cymene)Cl2(PPh2H)] and [Ru(η 6-cymene)Cl 2 (PPh2OH)] complexes

Abstract

The reaction of [Ru(η 6-cymene)Cl2]2 and PPh2Cl in the ratio 1:2 gives a stable [Ru(η 6-cymene) Cl2(PPh2Cl)] complex. Attempts to make the cationic [Ru(η 6-cymene)Cl(PPh2Cl)2]Cl with excess PPh2Cl and higher temperatures led to adventitious hydrolysis and formation of [Ru(η 6-cymene)Cl2(PPh2OH)]. Attempts to make a phosphinite complex by reacting [Ru(η 6-cymene)Cl2]2 with PPh2Cl in the presence of an alcohol results in the reduction of PPh2Cl to give [Ru(η 6-cymene)Cl2(PPh2H)] and the expected phosphinite. The yield of the hydride complex is highest when the alcohol is 1-phenyl-ethane-1,2-diol. All three half-sandwich complexes are characterized by X-ray crystallography. Surprisingly, the conversion of chlorodiphenylphosphine to diphenylphosphine is mediated by 1-phenyl-ethane-1,2-diol even in the absence of the ruthenium half-sandwich precursor. [Figure not available: see fulltext.]