Structural, Electrochemical and Catalytic Elucidation of Cyclooctadiene Ru(II)‐Nitrile Complexes of the Type [RuCl₂(cod)(NCR)₂]

Abstract

The facile synthesis of a range of eleven cyclooctadiene Ru(II) complexes of the type [RuCl 2 (cod)(NCR) 2 ] featuring different nitrile ligands using two synthetic routes is reported. The solidstate characterization (SCXRD) of twelve complexes is also described. Complex instability in solution led to spontaneous dimerization to yield a dimeric complex. Using these complexes, varied catalytic activity was observed in six different transformation reactions, of which the transfer hydrogenation of ketones was the highest (yields of 99 % after 30 minutes, TOF = 156 h À 1 ). The electrochemical (CV), DFT, and catalytic properties of the complexes evaluated showed that while the majority of the characteristics of the complexes are comparable, three complexes stood out with the lowest catalytic activity (16 % and lower), the highest (most positive) formal redox potentials for Ru II /Ru III (E 0 ' of up to + 1.4 V), as well as exhibiting some of the smallest energy gaps (as small as 1.21 eV) in the series.