Octachloro- and octabromoditechnetate(III) and their rhenium(III) congeners.
The compound (n-Bu4N)2Tc2Br8 was prepared by the metathesis of (n-Bu4N)2Tc2Cl8 with HBr (g) in dichloromethane and characterized by X-ray absorption fine structure spectroscopy and UV-vis spectroscopy. Analysis of the data gives a Tc-Tc distance of 2.16(1) A and a Tc-Br distance of 2.48(1) A. The Tc(III) oxidation state was inferred by the position of the edge absorption, which reveals a shift of 12 eV between (n-Bu4N)2Tc2Br8 and NH4TcO4. The analogous shift between (n-Bu4N)2Tc2Cl8 and NH4TcO4 is 11 eV. The UV-vis spectrum of Tc2Br8(2-) in dichloromethane exhibits the characteristic delta --> delta* transition at 13,717 cm(-1). The M2X8(2-) (M = Re, Tc; X = Cl, Br) UV-vis spectra are compared, and the position of the delta --> delta* transition discussed.
Poineau
Frederic
F
Harry Reid Center for Environmental Studies, University of Nevada Las Vegas, Las Vegas, Nevada 89154, USA. freder29@unlv.nevada.edu
Sattelberger
Alfred P
AP
Conradson
Steven D
SD
Czerwinski
Kenneth R
KR