Abstract Post-transition elements react with ligands, triphenylphosphine sulphide or selenide (Ph 3PS or Ph 3PSe), tri- p-tolylphosphine sulphide or selenide (T 3PS or T 3PSe) and 1,3-trimethylene bis-(diphenylphosphine sulphide or selenide) (PDPS or PDPSe) in suitable organic solvents forming complexes of compositions: MX 2. L(M = Zn, X = I, L = all except Ph 3PS: M = Cd, X = I, L = T 3PS, T 3PSe, M = Hg, L = T 3PSe, X = Cl, Br, I); ZnI 2·2Ph 3PS, Hg(NO 3) 2·2Ph 3PS, CdBr 2·3T 3PSe and 3Hg(NO 3) 2·4Ph 3PSe. All these have been characterized through elemental analyses, ir spectra (4000−200 cm −1) and molar conductance (nitrobenzene). Complexes are essentially nonelectrolytes. Tetrahedral structures have been assigned to all except a 1 : 3 complex which has been assigned a bridged octahedral structure.