Copper(II) complexes of pyrazoles

Complexes of pyrazole (pz), 3-methylpyrazole (3MePz) and 3,5-dimethylpyrazole (DMP) with copper(II) salts can be crystallized from aqueous and ethanolic solutions. With pyrazole and 3-methylpyrazole, tetragonal complexes of the type Cu X 2 L 4 (X = Cl, Br, 1 2 So 4 , NO 3 ) ; and CuX2L2 (X = Cl, Br) are formed. 3,5-Dimethylpyrazole forms CuX2(DMP)4 (X = Br, NO3); CuCl2(DMP)2, CuSO4(DMP)2·2H2O, CuCl2(DMP) and the copper(I) complex CuBr(DMP). The electronic spectra of the complexes are reported.