Factors determining the complex formation reaction of copper(II), nickel(II) and cobalt(II) chloride and copper(II) bromide
with 3,5-dimethyl-1-(hydroxymethyl)-pyrazole (HL) has been studied. Depending on experimental conditions, complexes with different
composition were obtained: [CuCl2(dmp)]2 (I), [CuCl2(dmp)2]2 (II), [CoCl2(dmp)2] (III) (dmp=3,5-dimethylpyrazole), [CuBr(L)]2 (IV), [CoCl(L)(EtOH)]4 (V) and [NiCl(L)(EtOH)]4 (VI). The compounds were characterized by FTIR spectroscopy, solution conductivity and magnetic measurements. The crystal structure
of [CoCl(L)(EtOH)]4 has been determined by single crystal X-ray diffraction. The thermal decomposition of the compounds was studied and found
to be continuous for all of the compounds. The desolvation mechanism of [MCl(L)(EtOH)]4 (M=Co(II), Ni(II)) is explained on the basis of the route of complex formation of CoCl2 with HL.