Linear and non-linear optical properties of arene-Fe-Cp complexes

Ionic [arene-Fe-Cp](+) fragments were used as electron accepters in combina tion with dimethylamino or pyridoneiminyl donors to form push-pull substitu ted chromophores. While a tolane derivative showed high second-order non-li near optical activity (measured by hyper-Rayleigh scattering), an analogous pyridoneimine derivative did not. With the help of an X-ray crystal struct ure analysis this discrepancy was traced back to a cyanine-like structure o f the imine. Semiempirical INDO/S calculations support this conclusion. (C) 1999 Elsevier Science S.A. All rights reserved.