Electronic properties of two band system, β′-Pd(dmit)2 salts

The electronic states of the β′-type Pd(dmit)2 salts were examined by 13C NMR under pressure. The ground states at ambient pressure are supposed to be Mott–Hubbard-type insulator. At 7 kbar, a peak anomaly of relaxation rate, 1/T1, at 30 K was observed in the Et2Me2P salt. It is associated with a metal–nonmetal transition. At 9 kbar, a metal–metal transition was found in this salt. We consider that this may be the sign of the overlap between the LUMO and HOMO bands.