Infrared spectroscopic study of hofmann-Td-type host-guest compounds Ni(benzoic acid)2M(CN)4.2g (M = Zn, Cd, Hg; G = 1,4-dioxane, aniline)

In this study, Hofmann-Td-type clathrates, formulated as Ni(BA)2M(CN)4.2G (BA = Benzoic Acid, M = Zn, Cd or Hg and G = 1,4-Dioxane, Aniline), have been synthesized chemically for the first time. Infrared spectra of the clathrates is recorded with FTIR spectrometer in the spectroscopic region of (4000-200) cm-1. The assignments are performed for the ligand molecule, M(CN)4 groups and guest molecules individually. The vibrational frequencies of the host-guest compounds are compared with frequencies of free benzoic acid. It has been observed that some of these vibrational frequencies are shifted with respect to the free molecule due to clathrate formation. The observed frequency shifts arise because of bounding metal, metal-ligand vibrational modes and couplings.The M(CN)42- anions and [Ni(BA)2]2+ cations in the host structures of the clathrates form a three dimensional polymeric structure. In this structure, M atom is surrounded in the tetrahedral form by four C atoms of cyanide anions. Ni atoms are also surrounded octahedrally by four N atoms of cyanide anions and O atoms of ligand molecule. The ligand molecule is bound to Ni atom directly whereas four CN groups are bound to each other. The M(CN)4 group is bounded the each other by Ni(BA)2 in the there dimensional lattice form. In the host structure formed, there are two different cavities namely ? and ß and guest molecules accommodates in these cavities.