Two Electrically Different Molecular Conductors Based on Unsymmetrical Au(III)-Dithiolene Complexes with Similar Crystal Structures

Abstract

The cation radical salt based on unsymmetrical metal-dithiolene complexes [Au(ppy)(C8H4S8)]2[PF6] (1) is a semiconductor with small activation energy under ambient pressure, and shows metallic behavior under high pressure. On the other hand, [Au(ppy)(C8H4S6O2)]2[BF4] (2) is an insulator in spite of the structural similarity. Effective conduction pathways through the S···S contacts were found in the crystal structure of1. However, the crystal of2 contains no such conduction pathways. Comparison of the energy band structures of1 and2 suggests that even a subtle difference in cation arrangements makes a remarkable difference between the electrical properties of1 and2.