Description
η5-Monocyclopentadienyliron(II)/ruthenium(II) complexes of
the general formula [M(η5-C5H5)(PP)(L1)][PF6] {M = Fe, PP =
dppe; M = Ru, PP = dppe or 2PPh3; L1 = 5-[3-(thiophen-2-yl)-
benzo[c]thiophenyl]thiophene-2-carbonitrile} have been
synthesized and studied to evaluate their molecular quadratic
hyperpolarizabilities. The compounds were fully characterized
by NMR, FTIR and UV/Vis spectroscopy and their
Introduction
The exploitation of organometallic chemistry for the synthesis
of compounds with non-linear optical (NLO) properties
has been mainly motivated by their use in optical devices.[
1] During the last two decades, significant work has
been published outlining the most important progress in
the field.[2–11] According to the overall results, the general
understanding is that second-order non-linearities are
strongly related to asymmetric push–pull systems. In the
case of organometallic compounds, the metal centre can be
bound to a highly polarizable conjugated backbone, thereby
acting as an electron-releasing or -withdrawing group. This
type of structural feature leads to large quadratic hyperpolarizabilities
arising from intense low-energy metal-to-li-
[a]
; Mendes, Paulo J. 
