Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.013 Å; R factor = 0.037; wR factor = 0.101; data-to-parameter ratio = 15.9.The title compound, {[Cu 2 (CN)(C 2 H 8 N 2 ) 4 (H 2 O)][Cu 2 Zn 2 -(CN) 9 ]} n , is a host-guest structure in which the host is constituted by the Zn II and Cu I atoms bridged by cyanide ions, and the guest consists of Cu II , ethylenediamine, a cyanide and a water molecule. The guest and host species are linked through five N-HÁ Á ÁN hydrogen bonds. Zn II and Cu I in the host (or cation), have tetrahedral coordination. Cu II in the guest (or anion) are penta-and hexacoordinated, leading to distorted square-pyramidal and square-bipyramidal structures, respectively Poly[[aqua--cyanido-tetrakis(ethylenediamine)dicopper(II)][nona--cyanidodizincate(II)dicuprate(I)]] G. Indramahalakshmi, A. Thamaraichelvan, R. Gandhidasan, S. Athimoolam and S. Natarajan Comment Cyanide-metal complexes which form host frameworks, is one of the archetypal host-guest materials and its discovery has spawned a very rich structural chemistry. Hofmann type clathrates of the general formula MLNi(CN) 4 .g (M=bivalent metal ion, L-Ligand, g-guest) have been studied extensively (Akyuz et al., 1974). However, studies on clathrates with

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.

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IR spectra of three tetracyanonickelate complexes with 1,9-diaminononane as ligand and three of their clathrates with guest nitrobenzene are presented. It is shown that they have similar structures and exhibit weak hydrogen bonding between the pi-electron cloud of aromatic guest and the ligand of the host lattice which is observed in all clathrates. A second type of hydrogen bonding is present between the NO 2 of nitrobenzene and the cyanide group of the lattice. The cyanide vibrational frequencies in the present clathrates are found to be in the order Cd-Ni-NB < Co-Ni-NB < Ni-Ni-NB due to increase in second ionization potential of outer metal ion. Declathration by heating shows that after the elimination of guest, the host lattice is stable since the IR spectra of the heated clathrate sample is the same as it's host. So there is only a very weak hydrogen bonding between the host and guest. These empty sites of host are occupied by moisture and retained as clathrated water. The host lattices are found to be similar to those of Hofmann-α,ω-diamino long chain alkane clathrates. The stability of these compounds are based on H-bonds involving NO 2 of nitrobenzene, pi cloud of the guest and the cyanide moieties.