Preparation, crystal structures, EHT band calculations and physical properties of κ-(EDS-EDT-TTF)2[Ag2(CN)3] and α-(BETS)2Ag(CN)2

Abstract

Preparation, crystal structures, EHT band calculations and physical properties of a semi-conducting κ-(EDS-EDT-TTF) ₂ [Ag ₂ (CN) ₃ ] (1) and a new metallic-like species α-(BETS) ₂ Ag(CN) ₂ (2) are reported. κ-(EDS-EDT-TTF) ₂ [Ag ₂ (CN) ₃ ] 1: M _r =625.3, monoclinic space group P2 ₁ /c, a=15.157(9), b=8.732(2), c=13.51(2) Å,β=90.94(3)°, V=1788 Å ³ , Z=2, D _c =2.324 g cm ^–3 , R=0.055 for 2572 reflections with F ² ≥2σ(F ² ). In this compound the organic molecules adopt the so-called κ type of packing. In the inorganic sublattice the [Ag ₂ (CN) ₃ ] ^– units form an infinite two-dimensional polymeric sheet. This compound shows a semi conducting behaviour, withσ _{300 K} =3.0×10 ^–4 S cm ^–1 and E _a =120 meV. α-(BETS) ₂ Ag(CN) ₂ 2: M _r =1304.4, orthorhombic space group P2 ₁ 2 ₁ 2, a=9.5839(8), b=4.983(3), c=34.645(6), V=1654 Å ³ , Z=2, D _c =2.618 g cm ^–3 , R=0.057 for 1136 reflections with F ² ≥2 σ(F ² ). Its crystal structure consists of two-dimensional organic sheets separated by linear Ag(CN) ₂ ^– anions. The organic molecules adopt the so-called α type of packing with a dihedral angle between two molecules belonging to two adjacent chains of ca. 78°. This compound shows metallic behaviour in the range 300-2 K, with σ _{300 K} =100 S cm ^–1 .