Nickel and palladium phosphinimine-imine ligand complexes

Abstract

The imine (C₆H₃i-Pr₂)NCMe₂1 was prepared and used to make the phosphine (C₆H₃i-Pr₂)NC(Me)CH₂PPh₂2. Oxidation with the substituted arylazide resulted in the isolation of the phosphinimine-imine species (C₆H₃i-Pr₂)NC(Me)CH₂PPh₂(NC₆H₃i-Pr₂) 3. The ligand 3 forms the neutral Ni-complex NiBr₂((C₆H₃i-Pr₂)NC(Me)CH₂PPh₂(NC₆H₃i-Pr₂)) 4 while attempts to prepare the analogous Pd species were unsuccessful. Reaction of 3 with n-BuLi produced the Li-salt Li(thf)((C₆H₃i-Pr₂)NC(Me)CHPPh₂(NC₆H₃i-Pr₂)) 5. Subsequent reaction with NiBr₂(dme) afforded [Ni((C₆H₃i-Pr₂)NC(Me)CHPPh₂(NC₆H₃i-Pr₂))(μ-Br)₂Li(thf)₂] 6. In related syntheses 5 reacted with NiBr₂(dme) or (PhCN)₂PdCl₂ and PPh₃ to give the complexes of formulation MX((C₆H₃i-Pr₂)NC(Me)CHPPh₂(NC₆H₃i-Pr₂))(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.