Poly(vinylene arsine)s with no aromatic substituent ([-CH=CR-AsMe-](n)) were prepared through a radical alternating copolymerization of acetylenic compounds having an alkyl substituent with an organoarsenic homocycle as an arsenic-atomic biradical equivalent. The radical reaction between 1-octyne and pentamethylcyclopentaarsine, with a catalytic amount of 2,2'-azobisisobutyronitrile without a solvent (60 degreesC, 10 h), produced the corresponding poly(vinylene arsine)s (45% yield). The copolymers obtained were soluble in tetrahydrofuran, chloroform, hexane, and so on. The copolymers were characterized with H-1 and C-13 NMR spectra. The number-average molecular weights of the copolymers were estimated with gel permeation chromatography (chloroform and polystyrene standards) to be 6500. The copolymers showed an emission property attributable to the n-pi* transition in the main chain. Irradiation by an incandescent lamp of a mixture of 1-octyne and 1 also produced poly(vinylene arsine)s. The conversion rate of 1-octyne during the copolymerization with 2,2'-azobisisobutyronitrile was measured with gas chromatography analysis and was found to be much slower than that of phenylacetylene. A radical terpolymerization of cyclo-(AsMe)(5) with 1-octyne and styrene was carried out to yield the terpolymer. (C) 2004 Wiley Periodicals, Inc.