Third order nonlinear optical properties of group 4 metallocenes

Article abstract of DOI:10.1016/0277-5387(94)00337-E

The third order nonlinear optical (NLO) coefficients (γ) of Ti, Zr, and Hf metallocene halides, acetylides and alkenylzirconocene compounds were measured with a third harmonic generation technique with a fundamental laser frequency of 1908 nm. Metallocene halide compounds have γ of less than 5E-36 esu. Titanocene bisphenylacetylide has the largest γ (92E-36 esu) of the metallocene acetylide compounds. The γ of the metallocene acetylide complexes are significantly larger than the sum of the free organic acetylene and the metallocene halide compounds. Cp2Zr(Cl)CH=CH-1,4-phenyl-CH=CH(Cl)ZrCp2 has the largest γ (154E-36 esu) of any of the group 4 metallocene compounds studied. The origin of this optical nonlinearity is most likely due to a conjugated π system, which involves the Cp-metal bonding network and like symmetry orbitals of the vinyl and acetylide ligands.