Reduction of the NO + ligand in ‘half-sandwich’ ruthenium derivatives

Abstract

The reduction of the tetrafluoroborate salts of the ruthenium nitrosyl dicationic [Ru(η 5-C 5R 5)(NO)(L) 2] 2+ (R=Me, L=PMe 3, 1a; PMe 2Ph, 1b; R=H, L=PPh 3, 2d) and monocationic complexes [Ru(Me)Cp*(NO)L] + (L=PMe 3, 3a; PMe 2Ph, 3b) (Cp*=η 5-C 5Me 5) has been studied by electrochemical and spectroscopic (IR, NMR, EPR) techniques. The nitrosyl complexes 1a, 1b and 2d exhibit two successive one-electron cathodic processes due to the sequential reduction of coordinated NO + to NO and NO −, respectively. Chemical reduction yields products of rearrangement of the intermediates which have been spectroscopically characterized. EPR studies and theoretical calculations show that in the first one-electron reduction product the electron interacts with the NO nitrogen atom and that the RuNO moiety presents significant distortion from linearity. The X-ray structure of the related [Ir(Me) 2Cp*(NO)]BF 4 has been determined.