Keywords: Cadmium(II)/mercury(II) Halide/pseudohalide Polyamine Ligand rearrangement X-ray structure a b s t r a c t Coordination compounds of the types [Hg(atta)][HgCl 4 ] (1), [Cd 5 (apda) 2 Cl 10 ] n (2), [Cd 3 (apda) 2 (N 3) 4 ] n (ClO 4) 2n (3) and [Cd 2 (bpda)(NCS) 4 ] n (4) [atta = 4-(2-aminoethyl)-triethylenetetramine; apda = N-(2-ami-noethyl)piperazine-1,4-diethylamine; bpda = N,N 0 -bis(2-aminoethyl)piperazine-1,4-diethylamine] are isolated using tetraethylenepentamine (tepa; for 1–3)/pentaethylenehexamine (peha; for 4) in presence of cadmium(II)/mercury(II) halides/pseudohalides. Structural studies reveal that polyamines tepa and peha undergo interesting in situ rearrangement to afford atta/apda and bpda ligands, respectively. Asym-metric unit in 1 comprises of discrete [Hg(atta)] 2+ cation and [HgCl 4 ] 2À anion. Compound 2 consists of neutral pentanuclear core [Cd 5 Cl 10 ] formed by three different types of chloride bridges propagating through binucleating bitridentate character of apda to afford a 1D ladder structure. 2D coordination poly-mer 3 with (4 1 6 2)(4 2 6 2) topology is formed through double l 1,1 -and single l 1,3 -azide bridges and binu-cleating behavior of apda. Alternating double l 1,3 -thiocyanate and binucleating bis(tridentate) bridges in 4 result in a 1D zig-zag chain. Different kinds of non-covalent interactions promote dimensionalities in 1–4. Thermal behaviors of 1–4 are examined.