Cadmium dicarboxylate coordination polymers incorporating a long-spanning organodiimine: in situalkene isomerization and an unprecedented chiral 658 two-dimensional network

Abstract

Reaction of cadmium nitrate, maleic acid, and N,N′-bis(4-pyridylmethyl)piperazine (bpmp) in a methanol/water mixed solvent system at 25 °C resulted in an unexpected in situisomerization and formation of {[Cd(fumarate)(bpmp)(H₂O)₂]·2H₂O}_n (1), which exhibits a system of mutually interpenetrated [Cd(fumarate)(bpmp)(H₂O)]_n grid-like coordination polymer layers. A similar reaction using cadmium chloride and succinic acid produced {[Cd(succinate)(bpmp)(CH₃OH)]·2H₂O}_n (2), which manifests a chiral two-dimensional coordination polymer network with an unprecedented 6⁵8 topology. The differences in the conformations of the four-carbon dicarboxylate tethers (anti in 1, gauche in 2) and cadmium coordination environment (octahedral in 1, pentagonal bipyramidal in 2) play a significant role in structure direction during self-assembly. Thermal properties of 1 and 2 are also reported.