The first polymorph, κ″-(ET) 2Cu[N(CN) 2]Cl, in the family of κ-(ET) 2Cu[N(CN) 2] X ( X=Cl, Br, I) radical cation salts

• Published in: Journal of solid state chemistry Vol. 182; no. 3; pp. 617 - 621
• Main Authors: Kushch, N.D., Kazakova, A.V., Buravov, L.I., Chekhlov, A.N., Dubrovskii, A.D., Yagubskii, E.B., Canadell, E.
• Format: Journal Article
• Language: English; Russian
• Published: Amsterdam Elsevier Inc 01.03.2009; Elsevier
• Subjects: Conductivity; Electronic structure; Polymorph; Radical cation salt; Structure; Polymorph; Conductivity; Electronic structure; Structure; Radical cation salt
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2008.10.035

The first polymorph, κ″-(ET) 2Cu[N(CN) 2]Cl, of the well known Mott insulator κ-(ET) 2Cu[N(CN) 2]Cl has been prepared and its crystal and electronic structures have been examined. The polymorph has monoclinic symmetry in contrast with the orthorhombic one of the isostructural κ-salts of the family (ET) 2Cu[N(CN) 2] X ( X=Cl, Br, I). The monoclinic phase exhibits a layered structure in which the conducting layers are packed in a κ-type arrangement and the anion sheets consist of polymeric zigzag chains formed by Cu[N(CN) 2]Cl units. The main structural differences with the orthorhombic κ-salts are that the anion sheets are disordered and the ET molecules are less planar. The new polymorph shows metallic type resistivity down to 4.2 K. The first polymorph, κ″-(ET) 2Cu[N(CN) 2]Cl, of the well known family of isostructural κ-salts (ET) 2Cu[N(CN) 2] X ( X=Cl, Br, I) has been prepared and its crystal and electronic structures have been examined. The main structural differences between the monoclinic and orthorhombic polymorphic κ-salts are that in the first the anion sheets are disordered and the ET molecules are less planar. The new polymorph shows metallic type resistivity down to 4.2 K.