CRYSTAL-STRUCTURES AND MAGNETIC-PROPERTIES OF BIPYRIDINE COPPER(II) COMPLEXES

The synthesis, structure and magnetic properties of [Cu(diMe-bipy)Br-2 ] are reported (diMe-bipy=4,4'-dimethyl 2,2'-bipyridine). The complex has a polymeric structure composed of [Cu(diMe-bipy)Br-2] subunits lin ked via bridging bromine atoms. Each copper atom is hexacoordinated in a distorted octahedral coordination environment. Clystallographic dat a: monoclinic, space group C2/c, Z=4, unit cell of dimensions a=18.312 (7), b=9.818(2), c=7.486(2)Angstrom, beta=107.750(0)degrees at 293 K. The best fit of the magnetic susceptibility data by the uniform Heisen berg chain model for S=1/2 ions yields values for the exchange couplin g constant of -0.46 cm(-1) The magnetic susceptibility of the dimeric [Cu(diMe-bipy) Cl-2](2).0.5H(2)O exhibits a maximum near 12 K that is indicative of an antiferromagnetic interaction between the two metal c enters. The best fit of the experimental data by the Bleaney-Bowers eq uation was obtained with g=1.95 and J=-6.99 cm(-1).