MCl2 (M = Ni, Co, Sn, or Mn) and PPh3 together acted as a catalyst for the radical polymerization of methyl methacrylate (MMA) in the presence of ethyl 2-bromoisobutyrate as an initiator. The four systems all led to conventional radical polymerizations, which yielded polymers with a weight-average molecular weight/number-average molecular weight (M-w/M-n) ratio greater than 2.0 and became well controlled when a certain amount of FeC1(3)(.)6H(2)O was added. The polymerizations of MMA catalyzed by these four FeCl3-modified catalyst systems provided well-defined polymers with low polydispersities (M-w/M-n < 1.28). (c) 2005 Wiley Periodicals, Inc.