Syntheses and NLO properties of chromium carbonyl arene complexes with conjugated side chains: The amphoteric nature of chromium carbonyl complexation in push-pull chromophores
Tjj. Muller et al., Syntheses and NLO properties of chromium carbonyl arene complexes with conjugated side chains: The amphoteric nature of chromium carbonyl complexation in push-pull chromophores, ORGANOMETAL, 18(24), 1999, pp. 5066-5074
Donor- and acceptor-substituted alkynylated chromium carbonyl arene complex
es Cr(CO)(2)L(eta(6)-R-1-C6H4)(C=C)(n)R-2 (1, n = 1, L = CO, PPh3, R-1 = H,
o-formyl, R-2 = p-C6H4-NMe2, p-C6H4NO2, ferrocenyl; 3, n = 2, L = CO, R-1
= H, R-2 = p-C6H4-NMe2, p-C6H4-NO2, ferrocenyl) are easily accessible by So
nogashira alkynylations of chloroarene complexes and Cadiot-Chodkiewicz cou
plings of bromoalkynes with the complexed phenyl acetylene 1a (n =, L = CO,
R-1 = R-2 = H), respectively. The Horner-Emmons-Wadsworth olefinations of
the Cr(CO)(3)-complexed benzylphosphonate and (hetero)aromatic aldehydes gi
ve rise to numerous alkenylated chromium carbonyl arene complexes (E)(n)-Cr
(CO)(3)(eta(6)-C6H5)(CH=CH)(n)R-1 (6, n = 1-3, R-1 = p-C6H4-NMe2, p-C6H4-NO
2, 2-(4-nitrothienyl)). The linear (UV/vis spectral and the nonlinear optic
al properties (hyper Rayleigh scattering measurements) of the complexes 1,
3, and 6 reveal that the chromium carbonyl arene fragment behaves electroni
cally amphoteric, i.e., as an electron donor or electron acceptor depending
on the substituent on the far end of the conjugating bridge. The first hyp
erpolarizability beta-values (beta(333)(0) = (8-41) x 10(-30) esu) are foun
d to be similar to those of related ferrocenyl compounds.