Ruthenium Arene Derivatives with PN Hemilabile Ligands. P-C Cleavage and Phosphine to Phosphinite Transformation

Complexes of formula [RuCl2(arene)(κ1-dpim)] (dpim = 2-(diphenylphosphino)-1-methylimidazole) (arene = p-cymene, 1a; C6H6, 1b) were prepared by the reaction of [RuCl2(p-cymene)]2 or [RuCl2(C6H6)(CH3CN)] with dpim. Complexes 1a and 1b were structurally characterized by NMR spectroscopy and X-ray diffraction. The reaction of these precursors with BF4- salts led, in dichloromethane, to cationic complexes of formula [RuCl(arene)(κ2-dpim)]BF4 (arene = p-cymene, 2a; C6H6, 2b). However, in methanol the products were unexpected phosphinite derivatives of the type [RuCl(arene)(HImMe){κ1-PPh2(OMe)}]A (A = BF4, arene = p-cymene, 3a; C6H6, 3b; A = BPh4, arene = p-cymene, 3d) (ImMe = methylimidazole). This transformation implies the existence of an easy P−C bond cleavage and phosphine functionalization with methanol at room temperature. The precursors 1a,b or the analogous derivative with 2-(diphenylphosphino)pyridine (PPh2py), [RuCl2(p-cymene)(κ1-PPh2py)], 1c, reacted with HBF4 to give cationic derivatives by protona...