Ruthenium Complexes with Tetraphenylimidodiphosphinate: Syntheses, Structures, and Applications to Catalytic Organic Oxidation

Treatment of Ru(PPh₃)₃Cl₂ with K(tpip) (tpip⁻ = [N(Ph₂PO)₂]⁻) afforded Ru(tpip)(PPh₃)₂Cl (1), which reacted with 4-t-Bu-C₆H₄CN, SO₂(g), and NH₃(g) to give Ru(tpip)(PPh₃)₂Cl(4-t-BuC₆H₄CN) (2), Ru(tpip)(PPh₃)₂Cl(SO₂) (3), and fac-[Ru(NH₃)₃(PPh₃)₂Cl][tpip] (4), respectively. Reaction of [Ru(CO)₂Cl₂]_x with K(tpip) in refluxing tetrahydrofuran (THF) led to isolation of the K/Ru bimetallic compound K₂Ru₂(tpip)₄(CO)₄Cl₂ (5). Photolysis of cis-Ru(tpip)₂(NO)Cl in MeCN and wet CH₂Cl₂ afforded cis-Ru(tpip)₂(MeCN)Cl (6) and cis-Ru(tpip)₂(H₂O)Cl (7), respectively. Refluxing 6 in neat THF yielded Ru(tpip)₂(THF)Cl (8). Treatment of Ru(CHR)Cl₂(PCy₃)₂ (Cy = cyclohexyl) with [Ag(tpip)]₄ afforded cis-Ru(tpip)₂(CHR)(PCy₃) [R = Ph (9), OEt (10)]. Complex 9 is capable of catalyzing oxidation of alcohols and olefins with N-methylmorpholine N-oxide and iodosylbenzene, respectively. The crystal structures of 2−7 and 9 were determined.