Structural and magnetic investigations on a new molecular quantum magnet

Abstract We report structural and magnetic investigations on a new hexacopper (II) siloxanolate cluster compound [C 92 H 102 Cu 6 N 8 O 29 Si 10 ]. The system, crystallizing in the triclinic space group P 1 (No. 2), has two identical macromolecules per unit cell. Each cluster contains six interacting Cu 2+ ions. We find a crossover from a 12-spin paramagnetic state at high temperatures to a 4-spin low-temperature configuration accompanied by the formation of an S =1 cluster ground state. A minimal magnetic model is discussed which may account for these observations.