From chain to layer structure: CdII coordination polymers derived from diphenic acid

Three CdII coordination polymers, {[Cd(py)2(dpa)](H2O)}n (1), {[Cd2(4,4′-bipy)2(dpa)2](H2O)}n (2) and {[Cd(bpe)(dpa)](H2O)}n (3) (py=pyridine; H2dpa= diphenic acid; 4,4′-bipy=4,4′-bipyridine; bpe=1,2-bis(4-pyridyl)ethane) were synthesized and characterized by X-ray crystal structure determination. In 1, two syn, anti-carboxylate groups in dpa bridge CdII forming a one-dimensional chain consisting of repeated eight-membered (–Cd–O–C–O–) rings, two pyridine nitrogen atoms occupy the axial positions of six-coordinated CdII. Two-dimensional layer complexes 2 and 3 can be regarded as an extension of 1 through μ-4,4′-bipy and μ-bpe replacing terminal pyridine, respectively.