SYNTHESIS OF POLYENES THAT CONTAIN METALLOCENES VIA THE LIVING POLYMERIZATION OF ETHYNYLFERROCENE AND ETHYNYLRUTHENOCENE

We describe the living polymerization of ethynylferrocene and ethynylruthenocene and the copolymerization of ethynylferrocene and TCDTF6 (TCDTF6 = 7,8-bis(trifluoromethyl)tricyclo[4.2.2.0(2,5)]- deca-3,7,9-triene). In all cases Mo(N-2,6-Me(2)C(6)H(3))(CHCMe(2)Ph)[OCMe(CF3)(2)](2) was the initiator that was employed. Charged systems were generated by terminating the living polymer with pyridinecarboxaldehyde followed by quaternizing the tertiary nitrogen with methyl iodide. Polyenes and copolyenes that contain up to similar to 50 double bonds are soluble. Charged polymers exhibit a more intense and red-shifted absorption. NMR studies suggest that ethynylferrocene adds to the initiator to give an unobservable intermediate alpha-substituted metallacyclobutene that opens to give the disubstituted (ferrocenyl/vinyl) propagating alkylidene. The structures of the first and second insertion products obtained by capping the chain with ferrocenecarboxaldehyde or pyridinecarboxaldehyde confirm that alpha addition takes place, a trans double bond is formed, and polymerization is virtually exclusively head-to-tail. Ethynylferrocene reacts extremely slowly with Mo(N-2, 6-Me(2)C(6)H(3))(CHCMe(2)Ph)(O-t-Bu)(2) via alpha addition and with Mo(NAr)(CHCMe(2)h)(OC6F5)(2)(quinuclidine) and Mo(NAd)(CHCMe(2)Ph)[OCH(CF3)(2)](2)(2,4-lutidine) via beta-addition.