[BETS]₂. C₆₀complex and BETS salts with square-planar platinate (II), nickelate (II) anions: (BETS)₄. Pt(CN)₄, (BETS)₄. Ni(CN)₄

The (BETS)(2).C-60 complex (1) and new radical cation salts based on bis(ethylenedithio)tetraselenafulvalene (BETS) with the square-planar [Ni(CN)(4)](2-), [Pt(CN)(4)](2-) anions were synthesized: (BETS)(4).Ni(CN)(4) (2), (BETS)(4).Pt(CN)(4) (3). The crystal structure of 1-3 is layered. The layers consisting of C-60 molecules are alternated with the layers composed of BETS molecules in 1. The obtained complex is classified as Molecular adduct in which the van der Waals interactions are predominant. The radical cation layers in the salt 2 are alternated with the anion layers along the c-direction of the unit cell. The salts retain metallic state down to 4.2 K. The band structure calculation of 2 shows 2-dimensional cylindrical Fermi surface, which is consistent with the theta- type structure and its conductivity.