Using an iterative sequence of Wittig olefination, reduction, oxidation, and condensationof an active methylene group to carbonyl, it was possible to prepare a series of organometallicpush-pull molecules [(CO)
5M=C(OCH
3)(-CH=CH-)
n(C
5H
4)Fe(C
5H
5), 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
was determined by hyper-Rayleigh scatteringexperiments. The
values ranged from 110 × 10
-30 to 2420 × 10
-30 esu in acetonitrile, andthey are among the highest reported for organometallic molecules so far. Electrochemicalmeasurements are consistent with the push-pull nature of these compounds.