Poly , living polymerization

Diisocyanobenzene (130) undergoes living polymerization to form the poly(quinoxaline-2,3-diyl)s 131, and the optically active helical polyfquinoxa-line-2,3-diyl) 132 is prepared from 131[123]. 

Metals have been incorporated into polyenes, either in the side chain as a consequence of the living polymerization of ethynylferrocene and ethynylruthen-ocene [ 179], or in the main chain as a consequence of polymerization of poly(fer-rocenylenedivinylene) and poly(ferrocenylenebutenylene) [180]. The former polymers were prepared in a living manner polymers containing as many as 40 equivalents of monomer were still soluble. In the latter only relatively low molecular weight materials were obtained. 

A Ta vinylalkylidene complex 6, confirmed by a single crystal X-ray analysis, was revealed to polymerize 2-butyne in a manner of living polymerization.The initiation efficiency is quantitative, and the living end can be end-capped with aromatic aldehydes. As polymers from symmetric acetylenes are generally insoluble, soluble poly(2-butyne) is accessible if the degree of polymerization is suppressed below 200. The NMR analysis of living oligomers of 2-butyne clearly indicates that both cis- and 7ra r-structures exist in the main chain. 

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