Recent Progress in MMX-Chain Complexes: Unique Electronic States and Characteristics Developed by Introducing Binary Countercations

Abstract

Abstract MMX-Type quasi-one-dimensional iodide-bridged diplatinum complexes (MMX chains) provide various electronic states and attractive physical properties. In this review, we summarize the recent progress in MMX chains consisting of pyrophosphite (pop) ligands. The MMX chains with binary countercations, which have short Pt–I–Pt distance and robust frameworks, form a new electronic state. They show reversible dehydration–rehydration accompanied by the change of electronic states and electrical conductivity. Relatively high electrical conductivity in the MMX chains with binary countercations enables us to investigate the negative differential resistance (NDR) and electrochemical characteristics in the solid state for the first time in MMX chains.