Di-ruthenium complexes having diphosphines and carbonyls: Formation, structure, and catalytic hydrogenation of alkynes

Abstract

Reaction of three selected diphos ligands, viz. 1,2-bis(diphenylphosphino)ethane (L1), 1,3-bis(diphenylphosphino)propane (L2) and 1,4-bis(diphenylphosphino)butane (L3), with [{Ru(CO)2Cl2}n] has afforded di-ruthenium complexes of type [Ru2(L)3(CO)2Cl4], (1–3). Crystal structure of complex 1 has been determined, and molecular structures of complexes 2 and 3 have been optimized through DFT method. Formation of the unexpected di-ruthenium complexes has been probed through DFT calculations. In dichloromethane solution all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows an irreversible oxidation within 0.79–1.53 V vs SCE, and an irreversible reduction within −1.20 to −1.33 V vs SCE. The di-ruthenium complexes efficiently catalyze hydrogenation of alkynes to the corresponding alkenes.