Evidence for intrinsic electrical conduction in the linear metal-chain semiconductor bis(1,2-benzoquinonedioximato)platinum(II), Pt(bqd) 2

Abstract

The four-electrode dc conductivity of single crystals of the linear metal-chain compound bis(1,2-benzoquinonedioximato)platinum(II), Pt(bqd) 2, measured parallel to the long axis of the crystals, reveals ohmic behavior over the temperature range 77–550°K, and averages to σ = 3.3 × 10 −3 Ω −1 cm −1 at room temperature. Unlike the well-characterized Magnus' Green Salt (MGS), Pt(NH 3) 4PtCl 4 ( σ = 5.5 × 10 −4 Ω −1 cm −1) , the present compound is found to be an intrinsic, small band gap semiconductor. The PtPt distance of 3.180 Å, the shortest yet observed in Pt(II) glyoximates, was determined by powder X-ray diffraction. The small band gap is related to the unusually high conductivity of Pt(bqd) 2, which is most reasonably interpreted in terms of this short PtPt separation. Preliminary results of polarized single crystal reflectance spectra demonstrating the anisotropic behavior of this compound are presented.