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

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 PNPRuI 2, 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 PNPRuMe 2 (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.