The organic π-electron metal system with interaction through mixed-valence metal cation: Electronic and structural properties of highly conducting anion radical salts (2, 5-R 1, R 2-DCNQI) 2Cu (DCNQI = N, N′ -dicyanoquinonediimine; R 1, R 2=CH 3, CH 3O, Cl, Br)

Abstract

The structural and electrical properties of new radical anion salts of dicyanoquinonediimine derivatives (R 1,R 2-DCNQI) 2M (R, R 2 = CH 3, CH 3O, Br, Cl; M =Cu) have been investigated. X-Ray diffraction experiments and XPS revealed the formal oxidation state of copper is Cu +1.3. (R 1,R 2-DCNQI) 2Cu(R 1, R 2=Me, Cl, Br) exhibited the cooperative structural phase transition at 150–250 K induced by the increase of the Jahn-Teller distortion around the Cu cation and the CDW instability of DCNQI column.