Nickel and palladium phosphinimine-imine ligand complexes

The imine (C(6)H(3)i-Pr-2)NCMe2 1 was prepared and used to make the phosphine (C(6)H(3)i-Pr-2)NC(Me)CH2PPh2 2. Oxidation with the substituted arylazide resulted in the isolation of the phosphinimine-imine species (C(6)H(3)i-Pr-2)NC(Me)CH2PPh2(NC(6)H(3)i-Pr-2) 3. The ligand 3 forms the neutral Ni-complex NiBr2((C(6)H(3)i-Pr-2)NC(Me)CH2PPh2(NC(6)H(3)i-Pr-2)) 4 while attempts to prepare the analogous Pd species were unsuccessful. Reaction of 3 with n-BuLi produced the Li-salt Li(thf)((C(6)H(3)i-Pr-2)NC(Me)CHPPh2(NC(6)H(3)i-Pr-2)) 5. Subsequent reaction with NiBr2(dme) afforded [Ni((C(6)H(3)i-Pr-2)NC(Me)CHPPh2(NC(6)H(3)i-Pr-2))(mu-Br)(2)Li(thf)(2)] 6. In related syntheses 5 reacted with NiBr2(dme) or (PhCN)(2)PdCl2 and PPh3 to give the complexes of formulation MX((C(6)H(3)i-Pr-2)NC(Me)CHPPh2(NC(6)H(3)i-Pr-2))(PPh3) (X = Br, M = Ni 7; X = Cl, M = Pd 8). The latter complexes 7 and 8 are phosphinimine-N-C bound. Structural studies of 2 and 4-8 are reported. The implications of these studies for the utility of this phosphinimine-imine ligand in olefin polymerization catalysts are considered.