Preparation, structural, electrical and magnetic properties of tetrathiafulvalene-Au(pdS)(2) salts (pds = pyrazine-2,3-diselenolate)

摘要

The combination of the electron donor tetrathiafulvalene, ttf, with the gold complex bis(pyrazine-2,3-diselenolate)aurate(III), Au(pds)(2)(-), afforded three different compounds depending on the preparative conditions: (ttf)(2)[Au(pds)(2)](2) (1), (ttf)(3)[Au(pds)(2)](2) (2) and (ttf)(3)[Au(pds)(2)](3) (3). Compound 1 was obtained by interdiffusion Of (ttf)(3)(BF4)(2) and (NBu4n)Au(pds)(2) in acetonitrile. Compounds 2 and 3 were obtained by electrocrystallisation from ttf and (NBu4n)Au(pds)(2) solutions in dichloromethane and acetonitrile respectively. These compounds were characterised by X-ray diffraction and electrical and magnetic studies. In the crystal structure of compound 1 are two types of ttf motifs dimers and isolated units. In the structures of compounds 2 and 3 the ttf units are arranged in trimers. In compound 2 the ttf units form trimerised segregated stacks separated by Au(pds)(2) units with their long axis almost parallel to the stacking axis. In 3 each ttf trimer is surrounded by a cage of four Au(pds)(2) units, and is arranged perpendicularly to the nearest neighbouring trimers. Compounds 1 and 2 exhibit a semiconducting behaviour with room temperature conductivities of 10(-4) S cm(-1) and 10(-2) S cm(-1), respectively. Compound 2 is essentially diamagnetic, while compound 1 shows a large paramagnetic susceptibility, at room temperature chi (p) = 13 x 10(-4) emu mol(-1), following a Curie-Weiss law above 50 K. Compound 3 is paramagnetic with a temperature independent EPR signal in the range 100-300 K. [References: 41]