The study of one-dimensional coordination polymers {Hg2Cl4L1}(n) (1), {HgBr2L1}(n) (2) and {Hg2Cl4L2}(n) (3) (L-1 = (S)P(OC2H5)(2)NHC6H4NHP(S)(OC2H5)(2) and L-2 = (S)P(OC2H5)(2)NC4H8NP(S)(OC2H5)(2)) is the first such structural study of Hg(ii) coordination polymers with (O)(2)(N)PS-based ligands. The mercury atoms adopt a distorted trigonal pyramidal environment, Hg(Cl)(3)(S) for 1 and 3 and Hg(Br)(2)(S)(2) for 2, and the difference observed in the stoichiometry of mercury halide to the thiophosphoramide ligand in 1 and 3 with respect to the one in 2 is a result of the formation of the Hg2Cl2 ring, however, the molar ratio 2:1 of HgX2 (X = Cl and Br) to ligand was used for the preparation of all three complexes. The strengths of mercury-sulfur and mercury-halide covalent bonds are evaluated by theoretical calculations (QTAIM and NBO) which show their principally electrostatic nature with a partial covalent contribution. The energies of interactions building supramolecular assemblies and intramolecular interactions, i.e. NHCl, NHBr, CHCl, CHBr, CHO, CHS and CH pi, are theoretically evaluated. The characteristic structural features arising from the aromatic/aliphatic linkers in the ligands and chloride/bromide attached to mercury are investigated by Hirshfeld surface analysis and fingerprint plots.