Synthesis, crystal structures and third-order nonlinear optical properties of two novel ferrocenyl Schiff-base complexes [Ag(L)₂](NO₃)(MeOH)(EtOH) and [HgI₂(L)] {L = 1,2-bis[(ferrocen-l-ylmethylene)amino]ethane}

Two novel ferrocenyl complexes [Ag(L)₂](NO₃)·(MeOH)· (EtOH) (1) and [HgI₂(L)] (2) {L = 1,2-bis[(ferrocen-l-ylmethylene)amino]ethane} ave been prepared and structurally characterized by means of X-ray single crystal diffraction. The central ion, silver(i) or mercury(II), has a distorted tetrahedral environment, the silver(I) ion coordinates with two L, and the mercury(II) ion binds one L and two iodine atoms. Their third-order nonlinear optical (NLO) properties were determined by Z-scan techniques in DMF solution. The results indicate that the two complexes exhibit very strong NLO absorption and strong self-focusing effects. The third-order NLO absorptive coefficients α₂ are 1.34 × 10^-8 m W^-1 for 1 and 3.1 × 10^-9 m W^-1 for 2. The refractive indexes n₂ for the two complexes are 1.15 × 10-¹⁸ and 8.02 × 10^-19 m² W^-1, respectively. The hyperpolarizability γ values are calculated to be 2.68 × 10^-30 esu for 1 and 1.44 × 10^-30 esu for 2. The γ values are several orders of magnitude larger than those of the reported aryl and vinyl derivatives of ferrocene.