Redox reactions of the boron subhalide clusters BnCln0/.bul.-/2- (n = 8 or 9) investigated by electrochemical and spectroscopic methods

Publication Type
Journal contribution
Authors
Speiser, B.; Tittel, C.; Einholz, W.; Schäfer, R.
Year of publication
1999
Published in
J. Chem. Soc., Dalton Trans.
Band/Volume
nnb/11
Page (from - to)
1741-1752
Abstract

The redox properties of the electron hyperdeficient boron subhalide clusters octachlorooctaborane(8), B8Cl8, nonachlorononaborane(9), B9Cl9, were studied in soln. by cyclic voltammetry at platinum or glassy carbon electrodes, and by 11B NMR as well as ESR spectroscopy. The neutral compds. undergo a spontaneous redn. by traces of moisture usually present even in dried solvents, and the voltammetric expt. starts from B8Cl8.bul.- or B9Cl9.bul.-. The radical anions were identified by ESR spectroscopy. Their formation leads to line broadening in NMR spectra of BnCln. Electrochem., they are quasireversibly reduced to the dianions, but oxidized in an ECcat (electrochem. step, catalytic chem. step) reaction with an essentially reversible electron transfer step to the neutral compds. The potential ordering for the two redox processes is normal in both clusters, being in accordance with the fact that structural changes accompanying the electron transfer are minor. The radical anion B8Cl8.bul.- is even more stable against disproportionation than B9Cl9.bul.-.

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