Variations around 1D coordination polymers built from the triarylamine scaffold and Hg(II) or Cd(II)

Abstract

Two tripodal ligands 1 and 2, derived from triarylamine (tris[4-(pyridin-4-yl)phenyl]amine (1) and tris(4′-(pyridin-4-yl)-[1,1′-biphenyl]-4-yl)amine (2)), have been synthetized and used for the formation of new 1D coordination networks. The synthesis and complete characterization of new 2 is described. Both ligands, that present the same geometry but different metrics, have been combined with V shape metalloligands MIIX2 (M = Hg and X = Cl or M = Cd and X = I). The solid-state structures of the four new 1D coordination polymers (1-HgCl2, 1-HgCl2·CHCl3, 2-HgCl2 and 2-CdI2) have been studied using X-ray diffraction on single crystals. The packing of networks and solvent molecules, when present within crystals, is mainly governed by π-π interactions. Depending on the nature of the ligand and the metalloligand, two types of coordination modes are observed: (i) ligand 1 may behave as a V shape connector with one pyridyl group remaining uncoordinated, and tetracoordinated Hg(II) cation leading, in 1-HgCl2, to a helicoidal arrangement; and (ii) ligands 1 and 2, when assembled with HgCl2 and CdI2 lead to a ladder-like structure (1-HgCl2·CHCl3, 2-HgCl2 and 2-CdI2), resulting from the recognition of the T-shape ligand (1 or 2), whereas all the pyridyl groups are involved in the coordination with the pentacoordinated M(II) cation. The tuning of the geometrical parameters of the 1D ladder-like networks appears possible through the initial choice of ligands.