Syntheses, Structures, and Properties of Copper(II) and Cobalt(II) Complexes with 1-(4-Chlorophenyl)Piperazinium Cations

Copper(II) and cobalt(II) halide complexes (H2L)[CuCl4]⋅H2O (I), (HL)n[CuCl3]n (II), (H2L)[CoCl4]⋅(H2L)Cl2⋅xH2O (where x = 1.5 (III) or 2 (single crystal)) and (HL)[Cu(H2O)Br3] (IV), L is 1‑(4-chlorophenyl)piperazine were synthesized. Two different [CuCl4]2– anions were found in the structure of I, which are bound to organic cations and crystal water molecules by a network of hydrogen bonds. In compound II, the [CuCl3]– anion is completed to a distorted square pyramid, forming polymer chains. Compound III is a mixed salt with the tetrahedral anion [CoCl4]2–. Thermal analysis data show that compound I loses water (~70°C) and HCl (~158°C); melting and subsequent decomposition occurs at 178°C. Compound II exhibits incongruent melting at 178°C with transition to the exothermic stage of destruction. The similarity of the thermal behavior of I and II at 178°C indicates the formation of II after the removal of volatile components from compound I. Complex III is thermally resistant to 70°C, with a total mass loss of 20% to 300°C corresponding to the removal of all water molecules and 3 HCl per formula unit. Compound IV melts above 80°C without loss of mass, decomposition is observed when heated above 150°C.