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

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 [Cd2(pbap)(OH2)2(N3)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 [Cd2(pfap)(μ1,3-NCS)(μ1,3-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 CdN5O and CdN5S 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.

Graphical abstractOne-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 [Cd2(pbap)(OH2)2 (N3)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 [Cd2(pfap)(μ1,3-NCS)(μ1,3-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. Both the complexes display intraligand 1(π–π∗) fluorescence and intraligand 3(π–π∗) phosphorescence in glassy solutions.Figure optionsDownload full-size imageDownload as PowerPoint slide