Infrared (IR) spectra of M(1,10-diaminodecane)Ni(CN)(4).1,5G (M = Co, Ni or Cd; G = chlorobenzene, 1,2-, 1,3- or 1.4-dichlorobenzene) clathrate compounds are reported. The spectral data suggest that these compounds are similar in structure to those of the Hofmann-diam-type clathrates. The host structure of these clathrates consists of planar infinite polymeric sheets, [M-Ni(CN)(4)](x) formed from Ni(CN)(4) anions coordinated to bridging M(1,10-diaminodecane)(2) cations. The Ni atoms are surrounded by four C atoms of CN groups in a square-planar environment. The M atoms are bound to four nitrogen atoms of the CN ions. The octahedral configuration of the M atom is completed by coordination of two ligand molecules. The sheets are stacked on top of another by bridging ligand molecules, in a way that every consecutive layer is superimposed. (C) 2000 Elsevier Science B.V. All rights reserved.