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

The facile synthesis of a range of eleven cyclooctadiene Ru(II) complexes of the type [RuCl2(cod)(NCR)(2)] featuring different nitrile ligands using two synthetic routes is reported. The solid-state 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(-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.

Automated summary

A facile synthesis method was reported for a range of cyclooctadiene Ru(II) complexes with different nitrile ligands, and solid-state characterization was performed for these complexes. The complexes displayed instability in solution, leading to spontaneous dimerization. Varied catalytic activity was observed using these complexes, with the highest activity observed in the transfer hydrogenation of ketones.