Ferrocene in conjugation with a Fischer carbene: synthesis, NLO, and electrochemical behavior of a novel organometallic push-pull system

Abstract

Using an iterative sequence of Wittig olefination, reduction, oxidation, and condensation of an active methylene group to carbonyl, it was possible to prepare a series of organometallic push-pull molecules [(CO)₅M=C(OCH₃)(-CH=CH-)_n(C₅H₄)Fe(C₅H₅), M = W, Cr, n = 1-4] in which ferrocene is the donor element and a Fisher carbene moeity is the acceptor group. The molecular first hyperpolarizability β was determined by hyper-Rayleigh scattering experiments. The β values ranged from 110 × 10^-30 to 2420 × 10^-30 esu in acetonitrile, and they are among the highest reported for organometallic molecules so far. Electrochemical measurements are consistent with the push-pull nature of these compounds.