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)]

摘要

New copper complexes with Dmt-Pyra-STF(=dimethylthio-pyrazino-selenathiafulvalene) as the ligand-trans-[Cu~IICl_2(Dmt-Pyra-STF)_2] (1) and [Cu_2~IBr_(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 theta-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 (theta=-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 sigma_(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_2~IBr_(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.