Electron rich bidentate phosphinimine-imine ligands: synthesis and reactivity of late transition metal complexes.

Electron rich phosphinimine-imine proligands Ph(3)PN(C(6)H(4))C(Ph)(NAr) (L(Ar)) (Ar = 4-(OEt)C(6)H(4) (OEt), 3,5-Me(2)C(6)H(3)(Xyl)) were synthesized in three steps from 2-aminobenzophenone. These compounds, along with previously reported L(Mes) and L(Tol) (Mes = 2,4,6-Me(3)C(6)H(2), Tol = 4-MeC(6)H(4)) were used to synthesize a series of tetracarbonyltungsten(0) complexes: L(Mes)W(CO)(4) (1), L(Tol)W(CO)(4) (2), L(OEt)W(CO)(4) (3), and L(Xyl)W(CO)(4) (4). The ligands were evaluated by analysis of the carbonyl stretching frequencies of the tungsten complexes and were shown to be better sigma-donors and poorer pi-acceptors compared to similar ligands in the literature. The coordination chemistry of the proligands was expanded to other late transition metals and L(Mes)CoCl(2) (5), L(Tol)CoCl(2) (6), L(Mes)NiBr(2) (7), L(Tol)NiBr(2) (8), L(Mes)ZnCl(2) (9), and L(Tol)ZnCl(2) (10) were synthesized by the direct reaction of L(Mes) and L(Tol) with the respective metal dihalide precursors. The complexes were fully characterized and the molecular structures of complexes 3, 6, 7, and 10 were reported. The synthesis of zinc complexes 9 and 10 was dependent on the steric bulk of the ligand. Complex 10 proved to be resistant to derivatization via a number of routes.