Anion to centre of metathesis

Substitution of the donor Cl in WCl (tungsten is the most frequently used transition metal in centres of metathesis) by a carbanion produces a grouping which is capable of further cycloalkene polymerization by metathesis [253] 

Reaction block copolymers, e.g. poly(styrene)-Z /ocA -poly(pentenamer), have also produced by this method. 

The possibilities of coordination centre transformations are being further intensively studied [254, 255]. 

Pichot et al. applied the spin-trapping technique to study the copolymerization of acrylonitrile with vinyl chloride or vinyl acetate [256]. Macroradicals terminated by the latter two units are trapped preferentially. The authors also noted suppression of cyclization by the spin-trapping agent cyclization is otherwise very common in acrylonitrile copolymerizations. 

In ionic polymerizations, the fraction of free ions and of both solvent-separated and contact ions pairs is determined spectrophotometrically by the measurement of electrical conductivity and by NMR chemical shifts. 

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