POLYMERIC ORGANOSILICON SYSTEMS .14. SYNTHESIS AND SOME PROPERTIES OF ALTERNATING POLYMERS COMPOSED OF A DITHIENYLENE GROUP AND A MONO-SILANYLENE, DI-SILANYLENE OR TRI-SILANYLENE UNIT

Poly[5,5' - (dimethylsilylene) - 2,2' - dithienylene] (4a), poly[5,5'-(methylphenylsilylene)-2,2'-dithienylene] (4b), poly[5,5'-(1,1,2,2-tetramethyldisilanylene)2,2'-dithienylene] (4c), poly[5,5'-(1,2-dimethyl-1,2-diphenyldisilanylene)-2,2-dithienylene] (4d), poly[5,5'-(1,2,2,2-tetrametbyldisilanylene)-2,2'-dithienylenel (4e), and poly[5,5'-(1,1,2,2,3,3 - hexamethyltrisilanylene) - 2,2'-dithienylenel were synthesized by dehalogenative coupling of the respective bis(2-bromothienyl)-substituted mono, di- and tri-silanes with magnesium in the presence of a catalytic amount of a nickel(II) complex in 16-99% yields. The polymers thus obtained are light-yellow solids and soluble in common organic solvents. Molecular weights, M(w), of the polymers were measured and found to be 7800-35 000 by gel-permeation chromatography relative to polystyrene standards. The photochemical properties of the polymers (4a-4d) having silylene and disilanylene units were investigated. Only poly[5,5'-(1,2-dimethyl-1,2-diphenyl-disilanylene)2,2'-dithienylenel (4d) was found to be photoactive, but the others were inactive. When the thin solid films prepared from the polymers 4a-4e by spin-coating were exposed to antimony(V) fluoride in vacuo, the films became conducting; their conductivities were determined to be 10(-2)-10(-3) S cm-1 by the four-probe method.