Synthesis, crystal structures and vapor adsorption properties of Hg(II) and Cd(II) coordination polymers derived from two hydrazone Schiff base ligands

Abstract

Four coordination polymers, [HgL1Br2]n (1), {[Cd(L1)2Cl2]·2CH3OH}n (2), [HgL2Cl2]n (3) and [Cd(L2)2Cl2]n (4), have been synthesized and characterized from two hydrazone Schiff base ligands (L1 and L2) with mercury(II) or cadmium(II) halide, respectively. In complexes 1 and 3, each mercury(II) center is five-coordinated with distorted square pyramidal geometry in 1D coordination polymers. In complexes 2 and 4, each cadmium(II) center is six-coordinated with slightly distorted octahedral geometry in 1D looped-chain structures. Interestingly, the ligands show different coordination sites in the formation of coordination polymers. In complexes 2, 3 and 4, the ligands coordinate to the metal centers by pyridine nitrogen atoms and amino nitrogen atoms, whereas in complex 1 it coordinates by pyridine nitrogen atoms and carbonyl oxygen atoms instead of amino nitrogen atoms.