Formation of 2-Azaallyl Cobalt(I) Complexes by Csp3–H Bond Activation

Three novel unsymmetrical η3-2-azaallyl cobalt(I) complexes, [(2-PPh2)C6H4]CH═N[CHC6H4(4-R)]Co(PMe3)2 (4–6) (R = H (4); Cl (5); and OMe (6)), were synthesized by the reactions of Schiff base ligands [(2-PPh2)C6H4]CH═N[CH2C6H4(4-R)] (1–3) (R = H (1); Cl (2); and OMe (3)) with CoMe(PMe3)4 via sp3 C–H bond activation under mild reaction conditions. Complex {[(2-PPh2)C6H4]CH═NCH3[CHC6H4(4-R)]Co(PMe3)2}I (7) as an 18e cobalt(III) salt was obtained through the reaction of 4 with iodomethane. The substitution reaction of complex 4 with carbon monoxide afforded the dicarbonyl cobalt(I) complex [(2-PPh2)C6H4]CH[N═CHC6H4(4-R)]Co(CO)2(PMe3) (8). The molecular structures of complexes 4–8 were determined by single crystal X-ray diffraction.