MOLECULAR HYPERPOLARIZABILITIES OF NEW BIMETALLIC FERROCENYL DERIVATIVES

We have investigated the influence of complexation of ferrocenyl derivatives on the second-order hyperpolarizabilities beta. This was performed using dc electric field induced second harmonic generation (EFISHG) technique at 1.34 and 1.9 mum. For these new bimetallic ferrocenyl derivatives, significantly increased beta values were observed. Our best beta value (123.5 x 10(-30) esu at 1.34 mum) is comparable to the highest reported values for organometallic complexes. The nature of the second metal ion has a weak influence on the beta values, in consequence to the change of geometry of the associated complex. The validity of the two-level model has been examined in detail: we found that it applies fairly well for the monometallic complexes if one takes into account only the low energy MLCT transition but the contribution of upper levels cannot be ruled out for bimetallic complexes.