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

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.

Graphical AbstractThe 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.Figure optionsDownload full-size imageDownload as PowerPoint slide