3RD-ORDER NONLINEAR-OPTICAL PROPERTIES OF GROUP-4 METALLOCENES

The third order nonlinear optical (NLO) coefficients (gamma) of Ti, Zr , and Hf metallocene halides, acetylides and alkenylzirconocene compou nds were measured with a third harmonic generation technique with a fu ndamental laser frequency of 1908 nm. Metallocene halide compounds hav e gamma of less than 5 x 10(-36) esu. Titanocene bisphenyl-acetylide h as the largest gamma (92 x 10(-36) esu) of the metallocene acetylide c ompounds. The gamma of the metallocene acetylide complexes are signifi cantly larger than the sum of the free organic acetylene and the metal locene halide compounds. Cp(2)Zr(Cl)CH=CH-1,4-phenyl-CH=CH(CI)ZrCp(2) has the largest gamma (154 x 10(-36) esu) of any of the group 4 metall ocene compounds studied. The origin of this optical nonlinearity is mo st likely due to a conjugated 71 system; which involves the pi-metal b onding network and like symmetry orbitals of the vinyl and acetylide l igands.