Abstract:

Halide-bridged one-dimensional Cu(Ⅱ) halide complexes [(CH₃)₂CHNH₃]CuBr_3-xCl_x(x=0—3) have been synthesized and magnetically studied. Magnetic measurements show that χ_mT value decreases with the decrease of the temperature, revealing the presence of overall antiferromagnetic interaction in the complexes. Above certain temperature, χ_mT value shows abrupt increase, originating from the occurrence of structure phase transition at the temperature(T_c=341 K). The Cu(Ⅱ) ion adopts enlarged octahedral structure, different from the square pyramidal structure in the low-temperature phase. The T_c value for complexes [(CH₃)₂CHNH₃]CuBr_3-xCl_x(x=1, 2) is lower than that of [(CH₃)₂CHNH₃]CuCl₃, which is due to the presence of comparatively weak Cu—Br bonds in former compounds. Possible structures of [(CH₃)₂CHNH₃]CuBr_3-xCl_x(x=1, 2) have been proposed by comparing the magnetic properties of [(CH₃)₂CHNH₃]CuX₃(X^-=Br^- or Cl^-) with [(CH₃)₂CHNH₃]CuBr_3-xCl_x(x=1, 2).

Key words: Copper complex; Structure phase transition; Magnetic property