Coordination polymers constructed from o-phthalic acid and diamines: Syntheses and crystal structures of the phthalate-imidazole complexes {[Cu(Pht)(Im) 2] · 1.5H 2O} n and [Co(Pht)(Im) 2] n and their application in oxidation catalysis

Abstract

Two new copper(II) and cobalt(II) coordination polymers, {[Cu(Pht)(Im) 2] · 1.5H 2O} n ( 1) and [Co(Pht)(Im) 2] n ( 2) (where Pht 2− = dianion of o-phthalic acid; Im = imidazole) have been synthesized and their crystal structures determined by X-ray crystallography. The structures of 1 and 2 comprise, respectively, [Cu(Im) 2] and [Co(Im) 2] units linked by bridging 1,6-phthalate ions to form infinite chains. Although there are two independent Cu atoms in the structure of 1, each copper(II) center adopts an approximately square planar coordination mode with two O atoms from different phthalate ions and two N atoms of Im. In complex 2, cobalt(II) atoms are tetrahedrally coordinated. Extended hydrogen bonding networks stabilize the three-dimensional structures in both complexes. Preliminary results show that 1 and 2 exhibit catalytic activity on the oxidation of cyclohexene using hydrogen peroxide as oxidant under aerobic conditions at ambient temperature.