The first coordination polymers with an [O]2[N]P(S)-Hg segment: a combined experimental, theoretical and database study

Abstract

The study of one-dimensional coordination polymers {Hg₂Cl₄L₁}_n (1), {HgBr₂L₁}_n (2) and {Hg₂Cl₄L₂}_n (3) (L₁ = (S)P(OC₂H₅)₂NHC₆H₄NHP(S)(OC₂H₅)₂ and L₂ = (S)P(OC₂H₅)₂NC₄H₈NP(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. NH⋯Cl, NH⋯Br, CH⋯Cl, CH⋯Br, CH⋯O, CH⋯S and CH⋯π, 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.