Piezochromism in nickel salicylaldoximato complexes: tuning crystal-field splitting with high pressure.

The crystal structures of bis(3-fluoro-salicylaldoximato)nickel(II) and bis(3-methoxy-salicylaldoximato)nickel(II) have been determined at room temperature between ambient pressure and approximately 6 GPa. The principal effect of pressure is to reduce intermolecular contact distances. In the fluoro system molecules are stacked, and the Ni⋅⋅⋅Ni distance decreases from 3.

Pressure suppression of charge order without metallisation in Cs2Au2I6.

Resistivity and powder X-ray diffraction measurements on Cs(2)Au(2)I(6) up to 320 kbar pressure show that the suppression of Au(+)/Au(3+) charge order above 55 kbar results in a non-metallic phase containing localised Au(2+) states that is irreversibly amorphised above 120 kbar, and a gradual metallisation observed above 175 kbar may result from decomposition within the amorphous material.