Organometallic NLO Polymers. 3. Copolymerization of Bridged Bis(ferrocenyl) and Bis(cyanoacetate) Monomers via the Knoevenagel Condensation.

摘要

The bridged bis(ferrocenyl) monomer ((N5-C5H4CHO)Fe(n5-C5H4))2SiMe2 (1) was prepared in two steps from (n5-C5H4SnBu3)2Fe. The bis(cyanoacetate) monomers, CNCH2CO2(CH2)nO2CCH2CN (2) where n = 4, 6, and 8 where prepared in high yield by reacting ethyl cyanoacetate with the appropriate diol in the presence of Ti(OC4H9)4. Knoevenagel polycondensation K2CO3, THF, 40 deg C of 1 and 2 afforded a new class of organometallic accordion copolymers. Average molecular weights for the accordion copolymers ranged from 9,100 to 26,600 with polydispersities of approximately 2.1. The Knoevenagel polycondensation reaction appeared to produce a mixture of E- and Z-isomers (9/1, respectively); however, isomerically enriched polymer (i.e. 98% E-isomer) was obtained through selective precipitation.