[RuCp(PR3)(CH3CN)2]PF6 (R = Ph, Me, Cy). Convenient Precursors for Mixed Ruthenium(II) and Ruthenium(IV) Half-Sandwich Complexes

The reaction of [RuCp(CH 3 CN) 3 ]PF 6 ( 1 ) with the monodentate ligands PR 3 (R = Me, Ph, Cy) affords the cationic complexes [RuCp(PR 3 )(CH 3 CN) 2 ]PF 6 ( 2a − c ) in high yields. The CH 3 CN exchange kinetics has been studied by NMR, suggesting a dissociative mechanism. Due to van der Waals repulsive interactions between PCy 3 and the nitrile ligands, CH 3 CN is particularly labile in 2c . The chemistry of 2a − c has been further investigated with respect to substitution and oxidative addition.