Azaborolinyl-komplexe XIV. Oxidationsreaktionen an bis(η5-1,2-azaborolinyl)cobalt-sandwichkomplexen

Abstract

Abstract The oxidation of the crystalline paramagnetic bis(a-alkyl(-trimethylsilyl)-2-methyl-η 5 -1,2-azaborolinyl)cobalt sandwich complexes (I) (alkyl = CH 3 , C(CH 3 ) 3 ) with iodine vapour leads to the diamagnetic cobalticinium analogous 18-electron cations in II. They are isolated as tri- and penta-iodide mixtures. The polyiodide ions I 3 − and I 5 − do not exert a distinct influence on the protons of the cations as is shown by the 1 H NMR spectra. Pure compounds are obtained as PF 6 − salts III by oxidation with the ferricinium cation. According to the 1 H NMR spectra the cations in II and III consist of isomers as the starting complexes, differing from each other by the clockwise (B13-N/B13-N) or anti-clockwise (B13-N/N13-B) orientation of the rings. The synthesis and X-ray structure analysis of the so far unknown bis(1,2-dimethyl-ψ 5 -1,2-azaborolinyl)cobalt (Ia) are described.