Crystal structure, Hirshfeld surface, novel XPS spectroscopy and magnetic properties of a hybrid solid with tetrahedral coordination sphere tetrabromocuprate (II)

The synthesis and physico-chemical characterization of an organic-inorganic hybrid material, (N, N'-bi-n-butyl-4,4′-bipyridinium tetrabromocuprate, has been reported. This hybrid has been characterized using IR, thermogravimetric and single-crystal X-ray diffraction analyses. In the title salt, (C₁₈H₂₆N₂)[CuBr₄], the CuBr₄ ^2 − ion shows distorted tetrahedral geometry. The tetrabromocuprate and N, N'-bi-n-butyl-4,4′-bipyridiniums are held together via non-classical C[sbnd]H ⋯ Br hydrogen bond to form a 3-D hybrid structure. The percentages of hydrogen bonding interactions are analyzed by fingerprint plots of Hirshfeld surface. The XPS spectrum exhibits the signals of coexistence of Cu^I and Cu^II ions. However, the hybrid shows EPR silent behavior at room temperature and variable-temperature magnetic susceptibility displays an isolation of Cu^II feature with C = 0.46 emu K mol^− 1 and θ approximate to − 0.06 K in 2– K as well. Such a novel nature is further analyzed and discussed.