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, [Hg L 1 Br 2 ] n ( 1 ), {[Cd( L 1 ) 2 Cl 2 ]·2CH 3 OH} n ( 2 ), [Hg L 2 Cl 2 ] n ( 3 ) and [Cd( L 2 ) 2 Cl 2 ] n ( 4 ), have been synthesized and characterized from two hydrazone Schiff base ligands ( L 1 and L 2 ) 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.