(tBu2PCH2SiMe2)2N]RuMe2: Synthesis and Reactivity of an Unsaturated Ruthenium Dialkyl Radical Species

Abstract

The reaction of PNPRuCl (PNP = ( t Bu 2 PCH 2 SiMe 2 ) 2 N - ) with excess MeLi at -78 °C, followed by addition of a one-electron oxidant, leads to the thermally stable (at 25 °C), low-spin, five-coordinate trivalent ruthenium complex PNPRuMe 2 , 1. For comparison PNPRuI2, 2, was also synthesized and shown equally to be a low-spin d 5 complex. Compound 1 reacts with NO to produce the diamagnetic ruthenium(II) complex PNPRuMe2(NO), 3, with H 2 to give PNPRu(H) 3 , 5, and with excess CO to produce PNPRu-(COMe)CO, 6. The unusual stability of 1 is suggested to arise from the steric encapsulation of the radical center provided by the extremely bulky pincer ligand, the low coordination number (5), and a non-redox-innocent amide functionality.