Abstract: The variable temperature(4～300 K) magnetic susceptibility of binuclear copper(Ⅱ) complex of the bibracchial lariat ether [Cu²L(OH) (ClO₄)₃Me²CO(L= N,N'-bis(8-quinolylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) (1) was measured in an appropriate magnetic field of 500000 A/m. The strongly antiferromagnetic interaction constants are as follows: J =-257.7 cm^-1, Zj'=-30.1 cm^-1. It is shown that there is an antiferromagnetic interaction between molecules. The | J | value (<500 cm^-1 ) is not large enough to lead to the diamagnetic coupling. The plot of χ_m-H, which is different from the normal plot of χ_m-H, is explained through the spin canting phenomenon. By analyzing the crystal structure of the complex and 3d orbitals of two Cu²⁺ cations, we suggest that the exchange path is through OH bridge. Compared with the other two analogous binuclear copper(Ⅱ) complexes coordinated by macrocycle ligand and bridged by OH, we analyzed the correlation between J value and the overlap of orbitals.

Key words: Binuclear copper(Ⅱ) complex, Bibracchial lariat ether, Magnetic properties