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RESEARCH PRODUCT

Crystal structure, magnetic properties and esr studies of (4-apyH)4[CuIIBr4] [CuIBr2]2: a novel Cu(II)⧹Cu(I) system containing bromocuprate(I) chains and isolated tetrabromocuprate(II) anions

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Abstract The synthesis, crystal structure, ESR spectra and magnetic properties are reported for the Cu(II)⧹Cu(I) compound (4-apyH)4[Cu3Br8] (4-apyH = C5H7N2 = 4-aminopyridinium). Single-crystals of the compound were grown by slow diffusion of n-hexane on an ethanolic solution of (4-apyH)2[CuBr4] · H2O. The crystal structure is made up of organic cations, isolated [CuIIBr4]2− anions and infinite [CuIBr2]nn− chains composed of edge-sharing CuIBr4 tetrahedra. N–H · · · Br hydrogen bond interactions between organic counter cations and inorganic anionic units are present and contribute to the cohesiveness of the crystal packing. Magnetic susceptibility measurements showed a good isolation of Cu(II) with a normal Curie behaviour in all the temperature range with C = 0.44 cm3 K mol−1 and θ ≈ −1 K. ESR experiments were made at different temperatures and showed an isotropic signal (g = 2.154) operating at the X-band, which was resolved towards an axial-type (g∥ = 2.31, g↑ = 2.10, 〈g〉 = 2.17) signal at the Q-band.