Synthese und Strukturen von 9,10-Dihydro-9,10-diboraanthracen-Derivaten / Synthesis and Structures of 9,10-Dihydro-9,10-diboraanthracene Derivatives

A series of alkyl and amino derivatives of the tricyclic organoborane system 9,10-dihydro- 9.10-diboraanthracene was synthesized and examined. The reactions of 9,10-dichlor-9,10-dihydro- 9,10-diboraanthracene ( la ) with suitable reagents yield the corresponding alkyl, aryl or amino derivatives 1c-h , respectively. The compounds have been characterized by 1 H, 13 C and 11 B NMR spectroscopy. X-ray structure analyses have shown that the amino derivatives have bent structures, while the H 2 N compound 1h is planar. Calculations were carried out to study the reasons for the deformation of some of the amino-substituted derivatives. These calculations indicate that steric reasons are responsible for the deformation. Electrochemical investigations show reversible reductions of the dimethyl derivative 1c leading to the radical anion and the dianion. Both anions have been structurally characterized by X-ray diffraction studies.