Thiocyanate cadmium(II) coordination compounds with 2,3,5,6-tetrakis(2-pyridyl)pyrazine – Synthesis, structure and luminescent properties

Abstract

Three new thiocyanate coordination compounds [Cd(NCS)2(μ-tppz)]n (1), [Cd(NCS)(NO3)(tppz)(H2O)] (2), [Cd2(μ1,3-NCS)2(NO3)2(μ-tppz)]n (3) have been successfully synthesized in the reaction of Cd(NO3)2·4H2O or CdCl2·2.5H2O with a versatile polydentate ligand (2,3,5,6-tetrakis(2-pyridyl)pyrazine – tppz) and NCS− anion. The resulted compounds were structurally characterized by single crystal X-ray diffraction analysis and further characterized by infrared spectra, powder X-ray diffraction and thermal analysis. The studies demonstrated a significant impact of the reaction conditions and cadmium salt on the final molecular structures. The compounds 1 and 3 displays an infinitive one-dimensional chain made up of cadmium(II) ions linked by only through tppz bridges (in 1) or a single thiocyanate bridges μ1,3-NCS− and tppz molecules (in 3). The structure 2 consist of the mononuclear, heptacoordinated molecules [Cd(NCS)(NO3)(tppz)(H2O)] assembled by π⋯π and C–S⋯π type interactions into three dimensional supramolecular network. The photoluminescence behavior of 1–3 was investigated in solid state. In addition, the luminescent properties of the mononuclear coordination compound (2) were examined in acetonitrile solution.