Syntheses, X-ray structures and properties of a dinuclear cadmium(II)azido and a polymeric cadmium(II)thiocyanato compounds containing bis(tridentate) congregators

Abstract

One-pot reactions of cadmium(II) perchlorate/nitrate, Schiff bases (pbap/pfap) and pseudohalides (sodium azide/ammonium thiocyanate) in a 2:1:4 molar ratio in MeOH–MeCN solvent mixtures at room temperature result in a dinuclear compound [Cd 2(pbap)(OH 2) 2(N 3) 4] ( 1) [pbap = N-(1-pyridin-2-ylbenzylidene)- N-[2-(4-{2-[(1-pyridin-2-ylbenzylidene)amino]ethyl}piperazin-1-yl)ethyl]amine] and a polymeric compound [Cd 2(pfap)(μ 1,3-NCS)(μ 1,3-SCN)(NCS) 2] n ( 2) [pfap = N-(1-pyridin-2-ylformylidene)- N-[2-(4-{2-[(1-pyridin-2ylformylidene)amino]ethyl}piperazin-1-yl)ethyl]-amine]. X-ray crystal structural analyses reveal a bis(tridentate) congregation behaviour of the hexadentate blocker (pbap/pfap) encapsulating two metal centers. Each cadmium(II) center in 1 and 2 is in a distorted octahedral geometry with CdN 5O and CdN 5S chromophores, respectively. In 1, the dinuclear units participate in intermolecular O–H⋯N hydrogen bonding between bound water O atoms and terminal azide N atoms, in combination with C–H⋯π interactions, resulting in a 3D supramolecular network with an intramolecular Cd⋯Cd distance of 6.473(2) Å. In the crystal lattice, the covalent 1D chain of 2 is further engaged in face-to-face π⋯π interactions from two terminal pyridine rings, which stabilizes the chain with an intradimer Cd⋯Cd separation of 6.640(5) Å. Both the complexes display intraligand 1(π–π ∗) fluorescence and intraligand 3(π–π ∗) phosphorescence in glassy solutions.