Random exchange in the spin ladder Cu(quinoxaline)X 2 (X = Cl, Br)

Abstract

Mixed halide versions of the spin ladder copper quinoxaline dihalide (X = Cl, Br) have been synthesized. X-ray crystallographic analysis shows the structures of the mixed halide versions are the same as those as the pure halide compounds; in the mixed-halide compounds, the larger bromide ions are preferentially found in the terminal, rather than the bridging, sites of the Cu 2X 4 dimeric units. Susceptibility studies show the rung interactions (within the dimeric units) remain unchanged upon mixing but the rail interactions (through the quinoxaline molecules) change systematically.