Vibrational Spectroscopic Analyses of (en)2-Td-type Clathrates

The clathrates of Hofmann-(en)2-Td-type, M(en)2M’(CN)4.Aniline (M=Cu,Cd; M’=Cd,Zn) and their hosts were synthesized with the confirmation using FTIR spectra. Hydrogen bonding interaction between π-cloud of phenyl ring of the guest molecule and ethylenediamine(en) of the host lattices was deduced from the upward shift in ν(CH)out of plane bending mode of aniline. A second type of hydrogen bonding between C≡N group of the host lattice and NH2 of aniline guest was also inferred from the downward shift in ν(C≡N) of the clathrates. The relative strength of H-bonding in the clathrates was found to be Hofmann-(en)2-Type > Hofmann-(en)2-Td-Phenol > Hofmann-(en)2-Td-Aniline. The presence of major peaks corresponding to various modes of guest aniline, ligand en and cyanide group in FT Raman spectra also confirms the formation of clathrates. Attempts to synthesize Ni(en)2M’(CN)4.Aniline (M’=Cd,Zn) resulted in the formation of M’(en)2Ni(CN)4.2Aniline (M’=Cd,Zn) due to the exchange of metal ions and greater stability of Ni(CN)4 unit.