Crystal engineering of versatile Hg(II) halides complexes of N,N,N′,N′-tetraalkyl substituted 3,5 pyridinedicarboxamides

Abstract

Two new ligands N,N,N′,N′-tetraisopropyl/butyl-3,5-pyridinedicarboxamide (L3-L4) and six of their Hg(II)X2 complexes (where X = Cl−, Br− and I−), have been synthesized and characterized using single crystal X-ray diffraction and spectroscopic techniques. Complexes of L3 (1–3) with HgCl2/Br2/I2, have dimeric structure, with the ligand behaving as a 2-C linker. Complexes 4–6 are 1D coordination polymers with either 3- or 2-C, L4 linker and bridging halides. A delicate balance of anion, solvent, denticity and conformation of the ligands on the ensuing molecular and crystal structures has been delineated. Various non-covalent interactions, extending the dimensionality of the complexes are calculated, analyzed and discussed. A significant role of semi-localized LP···π non-covalent interactions in stabilizing the basic dimeric unit in the complexes, has been discerned.