Syntheses, crystal structures, and physical properties of copper complexes with dimethylthio-pyrazino-selenathiafulvalene (=Dmt-Pyra-STF) as ligand: trans-[CuCl 2(Dmt-Pyra-STF) 2] and [Cu 2Br 2.5(Dmt-Pyra-STF)

Abstract

New copper complexes with Dmt-Pyra-STF (=dimethylthio-pyrazino-selenathiafulvalene) as the ligand— trans-[Cu IICl 2(Dmt-Pyra-STF) 2] ( 1) and [Cu I 2Br 2.5(Dmt-Pyra-STF)] ( 2)—have been synthesized by a vertical diffusion method. In complex 1, the donors form uniform stacking columns along the c axis to have a θ-type donor arrangement, but 1 is an insulator due to the absence of carriers. The magnetic susceptibility of 1 can be fitted to the Curie–Weiss rule ( θ = −9.02 K) and suggests that the oxidation state of Cu ions in 1 is 2+. In contrast, complex 2 has supramolecular chains along the c axis, which are formed by Cu I and Br −. In addition, this complex is a semiconductor with σ rt = 0.16 S cm −1 and E a = 0.10 eV. The magnetic susceptibility of 2 suggests that the oxidation state of Cu ions in 2 is 1+, namely [Cu I 2Br 2.5(Dmt-Pyra-STF) 0.5+]. Both complexes 1 and 2 demonstrate that pyrazino-fused STF derivatives can be coordinated to a copper even though the atomic orbital of Se is so large. Furthermore, we can firstly synthesize complex 2, in which both charge transfer and coordination occur simultaneously.