First-order phase transition in the organic metal κ-(BETS)2C(CN)3

Anion Conformation and Physical Properties in BETS Salts with the Nitroprusside Anion and its Related Ruthenium Halide (X = Cl, Br) Mononitrosyl Complexes: θ-(BETS)4[Fe(CN)5NO], (BETS)2[RuBr5NO], and (BETS)2[RuCl5NO]

“…Such structural changes could be responsible for the change in the resistivity behaviour around 40 K. Let us note, however, that among all presently known BETS and BEDT‐TTF cation radical based organic conductors, it is not rare that a first‐order phase transition cannot be rationalised in terms of electronic instabilities of the Fermi surface. In a very recent work,12 Canadell et al suggested that the first‐order phase transition observed in the κ‐(BETS) 2 C(CN) 3 salt mainly involves the anionic slabs and that the electronic structure of the donor slabs is only slightly altered by the transition. To obtain more insights into the mechanism of the transition observed for 1 , low‐temperature X‐ray investigations as well as magnetoresistance measurements could be of interest.…”

Conducting Organic Radical Cation Salts with Organic and Organometallic Anions

“…The first-order phase transition, which mostly affects the anion layer, has minimal effects on the Fermi surface. 187 Shubnikov-de Haas and de Haasvan Alphen oscillations have been observed in κ-(BETS) 2 C(CN) 3 in magnetic fields up to 25 T and under pressures to 9 kbar. 187,216,217 For the field perpendicular to the highly conducting planes, the Fourier spectrum of these oscillations exhibit four prominent peaks at F γ ) 230 T, F R ) 950 T, F β -F R ≈ 3400 T, and F β ) 4380 T, where the classical orbit on the cylinder is R and the magnetic breakdown orbit is β.…”

“…At room temperature disorder is found in both the [C(CN) 3 ] - anions and the ethylene groups of BETS. A first-order phase transition has been observed at 260 K, which is a result of an approximately 20° rotation of the [C(CN) 3 ] - anions . The anions are still disordered at 50 K, but at this temperature the ethylene groups order in a staggered fashion.…”

“…A first-order phase transition has been observed at 260 K, which is a result of an approximately 20°r otation of the [C(CN) 3 ]anions. 187 The anions are still disordered at 50 K, but at this temperature the ethylene groups order in a staggered fashion. This anion disorder has been suggested as a possible reason for the lack of superconductivity.…”

Polymorphism and Metallic Behavior in BEDT-TTF Radical Salts with Polycyano Anions

“…A possible reason explaining this lack of radical salts with this kind of anions may be the difficulty of obtaining single crystals of these compounds given the rigidity of the cyano groups and the lack of planarity of the -X(CN) 2 groups in the corresponding anions (except in the dca − anion, which, accordingly, is the most successful one). Although ET is the most used donor with this kind of anions, other donors such as bis(ethylenediseleno)tetrathiafulvalene (BETS-TTF) [39], bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) [40,41], TTF [42], and tetrathiotetracene (TTT) [43] have been used with these polycyano anions.…”