CuxM1-x(HCOO)(2)center dot 2H(2)O, (M = Mn, Co, Ni, Cd): Crystal structures and thermal behavior

A crystallographic and thermal study of the system CuxM1-x(HCOO)(2). 2H(2)O (M:Mn, x = 0.47; Co, x = 0.35; Ni, x = 0.37; Cd, x = 0.47) has been perfor med. The compounds, grown at room temperature, crystallize in space group P 2(1)/c and are isostructural with Cu0.5Zn0.5(HCOO)(2). 2H(2)O (1), with the cations sharing the two special position sites M1 and M2. In all cases, th e best refinement was achieved with the copper atoms occupying preferential ly the hexaformate-coordinated site M1, while the M2+ cations were mainly l ocalized in the M2 sites, in a mixed coordination environment. The compound s present a variety of thermal behaviors, with dehydration taking place at different temperatures and decomposition going from a simple single step pr ocess, as in the Zn compound, up to a complex three-stage one as in the Mn and Cd compounds. Decomposition products were identified by X-ray diffracti on on quenched samples at the end of each thermal stage. Some discrepancies of the present results with those in the literature are discussed. (C) 200 1 Academic Press.