The molecular structure of (where, Ln= La to Lu rare earths, and Tp = ring-unsubstituted tris (pyrazolyl) borate) complexes, is determined by DFT calculations at B3LYP/CEP-121G and PBE/TZP levels. The first order hyperpolarizability () and related properties (a, a0 and Da) of the title compounds are calculated by using B3LYP/CEP-121G in gas phase. The effect of solvent on nonlinear optical (NLO) response has been studied using DFT-CPCM model. Time dependent density functional theory (TD-DFT) and Slater's transition state (TS) have also been used to calculate the optical absorption spectrum of the lanthanide complexes in gas phase.

For the first time, our results demonstrate that the NLO activity enhancement is much more related to the direct contribution of 5d^x electrons, dipole moment and non-centrosymmetry of complexes to the first order hyperpolarizability than to the f orbital filling.