pπ-d Interaction in the (R1,R2-DCNQI)2Cu System

Pressure effects in the iodine-containing pπ-d system (DCNQI)2Cu are mainly described. Electrical and magnetic properties of (R1,R2-DCNQI)2Cu are quite sensitive to the substituents R1 and R2. A variety of substituent effects would be generally understood in terms of the amount of charge transfer from Cu to DCNQI which is sensitive to the N-Cu-N coordination angle. In the iodine-containing DCNQI-Cu system, however, an inter-stack LUMO···LUMO interaction would also play an important role.