Novel materials from bis(arene)metal-containing polyacrylonitrile

Novel bis(arene)metal-containing polyacrylonitrile materials have been prepared by the polycyanoethylation reaction between acrylonitrile and (arene)₂M (M = Cr or V; arene= PhH, C₆H₄Et₂ or mesitylene) in the absence of solvent. The resulting star-shaped molecules consist of a central (arene)₂M species with up to four polyacrylonitrile arms covalently bonded to the arene ligands. The materials are readily soluble and films can be cast from solutions in acetonitrile. The IR and solid state ¹³C NMR spectra (or EPR spectrum for the oxidized chromium-containing polymer) are consistent with the presence of a metal-arene bond and confirm the persistence of the sandwich structure. The properties of the thermolysed materials are consistent with the formation of conjugated naphthyridine-type structures. The value of |n₂| determined by the degenerate four-wave mixing technique at 1064 nm with a 6 ns pulse duration for a solution in conc. H₂SO₄ (1 g 1^-1) of the chromium-containing polymer pyrolysed at 350°C was found to be 0.8 × 10^-13 cm² W^-1 corresponding to |Re_χ⁽³⁾| = 0.4 × 10^-11 esu.