The radical anion salt [Fe{HC(pz)3}2](TCNQ)3 demonstrates conductivity and spin-crossover (SCO) transition associated with Fe(II) complex cation subsystem. It was synthesized and structurally characterized at temperatures 100, 300, 400, and 450 K. The compound demonstrates unusual for 7,7,8,8,-tetracyanoquinodimethane (TCNQ)-based salts quasi-two-dimensional conductivity. Pronounced changes of the in-plane direct-current resistivity and intensity of the electron paramagnetic resonance (EPR) signal, originated from TCNQ subsystem, precede the SCO transition at the midpoint T* = 445 K. The boltzmannian growth of the total magnetic response and structural changes in the vicinity of T* uniquely show that half [Fe{HC(pz)3}2] cations exist in high-spin state. Robust broadening of the EPR signal triggered by the SCO transition is interpreted in terms of cross relaxation between the TCNQ and Fe(II) spin subsystems.

Hybrid ion-pair crystals involving hexadentate [Fe(III)(3-OMesal 2 -trien)] + spin-crossover (SCO) cationic complexes and anionic gold complexes [Au(dmit) 2 ] − (1) (dmit = 4,5-dithiolato-1,3dithiole-2-thione) and [Au(dddt) 2 ] − (2) (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) were synthesized and studied by single-crystal X-ray diffraction, P-XRD, and SQUID magnetometry. Our study shows that both complexes have similar 1:1 stoichiometry but different symmetry and crystal packing. Complex 1 has a rigid structure in which the SCO cations are engaged in strong π-interplay with molecular surrounding and does not show SCO transition while 2 demonstrates a reversible transition at T sco = 118 K in a much "softer", hydrogen-bonded structure. A new structural indicator of spin state in [Fe(sal 2 -trien)] + complexes based on conformational analysis has been proposed. Aging and thermocycling ruined the SCO transition increasing the residual HS fraction from 14 to 41%. Magnetic response of 1 is explained by the AFM coupled dimers S = 5/2 with J 1 = −0.18 cm −1 . Residual high-spin fraction of 2, apart from a contribution of the weak dimers with J 12 = J 34 = −0.29 cm −1 , is characterized by a stronger interdimer coupling of J 23 = −1.69 cm −1 , which is discussed in terms of possible involvement of neutral radicals [Au(dddt) 2 ].have been undertaken to use the SCO compounds in magnetic memory or display devices, as well as multi-modal sensors [4][5][6]. Moreover, polyfunctional compounds combining the conductivity and the spin-crossover transition have been highlighted in connection with spin-dependent transport and single molecular switching [7][8][9]. Spin-lattice relaxation in the low-dimensional conducting networks of centrosymmetrical molecules is strongly suppressed. The hybrid structures implementing efficient exchange interaction between the SCO and conducting subsystems would facilitate the development of new molecular spintronic devices where the spin transport is controlled by spin-crossover complexes.Metal bis-1,2-dithiolene complexes, as organic donors and acceptors, possess a delocalized electron system as a planar central core M(C 2 S 2 ) 2 and present different formal oxidation states. This type of complex has been intensively studied as a component of molecular conductors [10][11][12]. In addition, metal dithiolene complexes have a rich variety of physical properties, such as Peierls instability of the low-dimensional systems and the quantum fluctuations [10,13]. Thus, both SCO and metal dithiolene complexes could undergo phase transition, and combining two components in one crystal structure might give rise to a novel molecular material with exotic phenomena.The interplay between spin-crossover and conductivity was already observed in some of such materials [14][15][16]. The majority of conducting SCO compounds are represented by the Fe(III) cation complexes with [M(dmit) 2 ] δ− anions [17-19]. As a first step in this way, Faulmann et al. have published a simple salt [Fe(sal 2 -trien)][Ni(dmit) 2 ] ...

Three systems [Fe(III)(sal 2 -trien)](TCNQ) n ·X (n = 1, 2, X = MeOH, CH 3 CN, H 2 O) showing spin-crossover transition, conductivity and ferromagnetic coupling were synthesized and studied by X-ray diffraction, Montgomery method for resistivity, SQUID magnetometry and X-band EPR. Spin-spin interactions between local magnetic moments of Fe(III) ions and electron spins of organic TCNQ network were discovered and discussed within the framework of intermolecular superexchange coupling.

The phase diagram of the quasi-binary Cu-TiS system has been studied in situ in the temperature-concentration plane for the first time. Phase transitions between 2D (layered) and 3D (cubic) phases in CuTiS (x = 0-0.5) intercalation compounds have been studied by the X-ray diffraction technique in the temperature range 20-1000 °C. It has been found that the stability of the layered phase is determined by the distribution of copper atoms between the octahedral and tetrahedral crystallographic sites. The occupation of octahedral sites dominates at low temperatures. Upon heating, tetrahedral site occupation is limited due to elastic lattice distortion and the layered phase becomes unstable and transforms to the spinel. Further heating allows the distribution of copper between octahedral and tetrahedral sites; the layered phase becomes stable again.

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