Polymers Possessing Other Titanacycle Units

On the basis of the fact that not only the titanacyclopentadienes but also many kind of titanacycles are important intermediates of the organic reactions as well as the catalytic cycles,the synthesis and the reactions of polymers containing other titanacycle systems, such as titanacyclobutene and diazatitanacyclohexadiene moieties, were also studied. 

Polymers with diazatitanacyclohexadiene units (32) could be prepared by the reaction of bis(cyclopentadienyl)dimethyltitanium and dicyano compounds (scheme 18). Protonation of the polymers gave rise to polymers with P-amino-ot,P-unsaturated ketone-repeating units (33). Judging from the versatile reactivity of the diazatitanacyclohexadiene derivatives, the polymers (32) might also serve as attractive reactive materials. 

In both cases, the structure of the organometallic polymers can be designed by the diyne monomers. The regiochemistry of the mainchain connections at each met-allacycle imit is affected by the nature of the substituents on diynes and/or the Ug-ands on the low-valent transition metal complexes. It was also demonstrated that the regioselectivity of the mainchain connections reflects directly on the character of the functional polymers obtained by the polymer reactions. That is, the organotitanium polymers with regiospecific mainchain coimections obtained from titanimn 

Buntz et al. reported the synthesis of arylene-ethynylene type polymers from regioisomerically pure cyclobutadienecohalt derivatives. See (a) M. Altmann, U. H. F. Bunz, Macromol. Rapid. Commun., 15, 785 (1994). (h) M. Altmann, U. H. F. Bunz, Angew. Chem., Int. Ed Engl, 34, 569(1995). 

Tomita, A. Nishio, T. Endo, Appl. Organometal. Chem., 12, 735 (1998). 

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