Synthesis, structure and calculated NLO properties of [(n-Bu)2Sn-μ-O-μ-OH-Sn(n-Bu)2(CH3CO2)]2 and its putative derivatives

Title compound[(n-Bu)2Sn-μ-O-μ-OH-Sn(n-Bu)2(CH3CO2)]2 was obtained accidentally by the reaction of n-Bu2SnCl2 with the metalloligand K2[Ni(CDC)2] in ethanol - water mixture while synthesizing a heterobimetallic complex [n-Bu2Sn Ni(CDC)2]. This has been characterized by micro analysis, UV–Vis, 1H, 13C and 119Sn NMR spectroscopy and the single crystal X-ray. The complex forms an interesting supramolecular architecture via (acetate)O⋯HO hydrogen bonding interactions which generates hydrophobic “pseudo-cage”. The electronic absorption bands of the title complex were assigned with the help of the time dependent density functional theory (TD-DFT) calculations. Density functional theory (DFT) calculations have been performed at the optimized molecular geometry of some of its putative derivatives e. g. trans p-amino cinnamic acid derivative 2; trans p-amino cinnamic acid and trans p-nitro cinnamic acid derivative 3; trans p-amino cinnamic acid and trans p-(N,N dimethylamino) cinnamic acid derivative 4. The first static hyperpolarizability (β) of the title compound and its derivatives were calculated with double numerical differentiation of total energies. The derivatives 3 and 4 showed three times and five times enhancement in the non-linear optical (NLO) responses than the standard p-nitroaniline (pNA).