Organometallic compound with lewis base I. Polymerization of vinyl‐compounds by organometallic compound/lewis base complex

AlEt3/α.α′‐dipyridyl (dip) and AlEt3/triphenylphosphine (PPh3) polymerized methyl methacrylate (MMA) and acrylonitrile (AN), and InEt3 dip, InEt3/PPh3, ZnEt2/dip and ZnEt2/PPh3 polymerized AN, while AlEt3, InEt3, and ZnEt2 by themselves did not polymerize MMA and AN. Styrene could not be polymerized by any of these organometallic compounds alone or together with a LEWIS base. The results from the copolymerization of AN with MMA by AlEt3/LEWIS base indicate that these polymerizations occur by an anionic mechanism. The coordination of the LEWIS base to the central metal ion of the aluminum complex reduces the electronegativity of the metal ion and increases the ionic character of the metal‐carbon bond which in turn induces the polymerization of polar vinyl compounds such as AN and MMA. The tacticity of the poly(MMA) obtained by AlEt3/LEWIS base catalysts obeys the statistics of BOVEY'S single parameter σ, although the propagating end is not a free anion nor solvent separated ion‐pair. A tentative explanation is presented.