Yufeng Weng

Evidence for theπ-d interaction comparing magneto-resistance in (EDT-DSDTFVO)2X, X=FeCl4, GaCl4

We have measured the electrical resistivities and magnetoresistances (MR) of (EDT-DSDTFVO)2X (X=FeCl4, GaCl4), where EDT-DSDTFVO stands for ethylenedithiodiselenadithiafulvalenothioquinone-1,3-dithiolemethide. These materials undergo gradual metal-insulator transitions at Tmin=52 K for FeCl4-salt and Tmin=30 K for GaCl4-salt, respectively. In spite of the similarity of the temperature dependence of the resistivity and its pressure effect, MR of both salts exhibit a clear contrast, i.e. FeCl4-salt shows negative and GaCl4, positive. Origin of the difference in the sign of MR between these salts are discussed in terms of the existence of π-d interaction.

Some New Nickel 1,2-Dichalcogenolene Complexes as Single-component Semiconductors

Abstract The complexes Ni(dmeds)(dmit), Ni(dmedt)(dmit), Ni(dpedt)(dsit), Ni(dpedt)(dmit), and Ni(dcdt)(dmit) (where dmeds is dimethylethylenediselenolate, dmedt is dimethylethylenedithiolate, dpedt is diphenylethylenedithiolate, dcdt is 1,2-bis-decylsulfanyl-ethene-1,2-dithiolate, dmit is 1,3-dithiol-2-thione-4,5-dithiolate, and dsit is 1,3-dithiol-2-thione-4,5-diselenolate) were prepared and characterized. The new complexes exhibit semiconducting behavior, with band gap values around 0.8 eV.

Preparation and Characterization of Some Nickel 1,2-Dithiolene Complexes as Single-Component Semiconductors

The unsymmetrical (mixed-ligand) nickel 1,2-dithiolene complexes Ni(pddt)(dmio) and Ni(pddt)(dmit) (where pddt is 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate, dmio is 1,3-dithiol-2-one- 4,5-dithiolate, and dmit is 1,3-dithiol-2-thione-4,5-dithiolate) were synthesized and characterized. The new complexes were found to be soluble in organic solvents, from which single crystals and/or thin deposits can be obtained. In the solid state, the compounds behave as single-component semiconductors with low room temperature conductivity values