HYDROBORATION POLYMERIZATION OF DICYANO COMPOUNDS .4. SYNTHESIS OF STABLE POLY(CYCLODIBORAZANE)S FROM DIALKYLBORANES

Dialkylboranes were used as a monomer in hydroboration polymerization of dicyano compounds. The bulk polymerization of(n-Bu(2)BH)(2) with al pha,omega-dicyanoalkanes gave the corresponding poly(cyclodiborazane)s consisting of boron-nitrogen four-membered rings. The obtained polyme rs were colorless gums and soluble in common organic solvents such as THF or chloroform. The molecular weights of the resulting poly(cyclodi borazane)s were higher than those prepared from monoalkylboranes. Poly (cyclodiborazane) a thus obtained showed a high stability toward air a nd moisture. The thermal stability was also much improved in compariso n with those prepared by hydroboration polymerization of dicyano compo unds with monoalkylboranes. After pyrolysis of poly(cyclodiborazane)s, some residue remained. This result indicates a possibility of poly(cy clodiborazane) as a polymeric precursor for the preparation of boron-c ontaining inorganic materials.