Synthesis of two Hofmann-type-like clathrates, characterizations, and investigation of their structures, spectroscopic and theoretical properties.

This study concerns two Hofmann-type-like clathrates using 4-aminopyridine (4AP) as ligands and the transition metal atoms copper (Cu) and zinc (Zn). These clathrates have the structural features of heteronuclear tetracyanonickelate(II) and contain H2O and 4AP molecules as guest molecules, respectively. These two clathrates were characterized by infrared spectroscopy (IR), elemental analysis, and single crystal X-ray diffraction (SC-XRD) techniques. Based on elemental and spectral data, the structural formulae describing these clathrates were found to be [Cu(II)(4AP)4Ni(μ-CN)2(CN)2]·H2O (1) and [Zn(II)(4AP)4Ni(μ-CN)2(CN)2]·(4AP) (2). In addition, the values of some optical, electronic, and thermochemical properties of the two obtained clathrates calculated with the Gaussian 03 program were compared with each other. Some theoretically calculated NLO properties of these clathrates were compared with similar properties of urea compound calculated with the same base set. The results showed that these clathrates are compounds worth investigating in terms of their NLO properties. Furthermore, the theoretical MEP maps, UV-visible region, NMR excitation transitions and Hirshfeld surface analyses of the clathrates were examined too. And it was seen that interactions such as C···H, H···H, N···H, N-H···N and C-H···π clearly play a role in the formation of their crystal structures.