Chain-transfer catalysis by vanadium complexes during methyl methacrylate polymerization

A series of V(CO)4(P–P) or HV(CO)4(P–P) ((P–P) = bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), and 1,4-bis(diphenylphosphino)butane (dppb)) complexes have been tested as chain-transfer catalysts for methyl methacrylate (MMA) polymerization. The chain transfer constants Cs (=ktr/kp), determined by Mayo plots, suggest that V(CO)4(dppe) is the most efficient chain-transfer catalyst among the complexes investigated (Cs = 750 at 70 °C).