Non-linear optical properties of the mixed-metal mixed-chalcogen clusters [Fe2(CO)6{μ-SeC(Ph)C(Se)}{(OEt)CCr(CO)5}] and [Fe2(CO)6Se2{μ-(CO)3Cr(η5-C5H(CH2Ph)(Ph)(OEt)}]

We report studies of the third-order optical non-linearity of the newly synthesized butterfly-shaped mixed-metal mixed-chalcogen clusters [Fe2(CO)6{μ-SeC(Ph)C(Se)}{(OEt)CCr(CO)5}] and [Fe2(CO)6Se2{μ-(CO)3Cr(η5-C5H(CH2Ph)(Ph)(OEt)}] using 532 nm, 6 ns laser pulses. Their effective non-linear absorption coefficient and non-linear index intensity coefficient are measured by the z-scan technique from which the corresponding cubic hyperpolarizabilities are evaluated. The obtained values indicate a high non-linearity comparable to some of the best values reported previously for cluster compounds. Both compounds show strong optical limiting, and the second compound exhibits non-linear scattering. Their photostability is superior to many of the previously reported highly non-linear clusters.