Structural diversity of cadmium coordination polymers based on an extended anilate-type ligand

Abstract

Six new coordination polymers (CPs) of cadmium based on an extended anilate-type ligand, 4,4′-(1,4-phenylenebis(azanylylidene))bis(3,6-di-tert-butyl-2-hydroxycyclohexa-2,5-dienone) (H₂L), have been synthesized. The series of coordination polymers includes [Cd(L)(DMF)] (1), 1D-CP [Cd(L)(dipy-1)]·2DMF (2A) and 2D-CP [Cd(L)(dipy-1)]·DMF (2B), [Cd₂(L)₂(dipy-2)(DMF)₂] (3), [Cd(HL)(CH₃COO)(dabco)] (4) and [Cd(L)(ur)₂]·(H₂L) (5) (where L – deprotonated form of H₂L, DMF – N,N′-dimethylformamide, dipy-1 – 4,4′-trimethylenedipyridine, dipy-2 – 4,4′-dipyridyl, dabco – 1,4-diazabicyclo[2.2.2]octane, ur – urotropine). The crystal structure and thermal decomposition of 1D- and 2D-coordination polymers are reported. The structural diversity of the synthesized compounds was found to depend on the additional neutral donor ligands in the cadmium coordination sphere. Thus, the introduction of the flexible N-donor ligand dipy-1 into the cadmium coordination sphere leads to the formation of two types of coordination polymers (1D and 2D). The use of the rigid ligand dipy-2 promotes the formation of “honeycomb” 2D-CPs. The use of shorter N-donor ligands dabco and ur leads to linear derivatives in which the ligands being coordinated by cadmium don't act as “crosslinkers” of the chains in the network.