Syntheses and Structures of 10‐Trimethylelement‐Substituted 1,8‐Dichloroanthracenes

Abstract

1,8-Dichloroanthracenes bearing EMe3 substituents at the 10-position (E = Si, Ge, Sn) have been synthesised by salt elimination reactions. The key compound, 10-bromo-1,8-dichloroanthracene (2), was quantitatively obtained by conversion of 1,8-dichloroanthracene with elemental bromine in dichloromethane. The EMe3-substituted anthracene compounds 1,8-dichloro-10-(trimethylsilyl)- (3), 1,8-dichloro-10-(trimethylgermyl)- (4) and 1,8-dichloro-10-(trimethylstannyl)anthracene (5) were completely characterised by multinuclear NMR spectroscopy and mass spectrometry. Their molecular structures in the crystalline state were analysed by X-ray diffraction experiments and compared with the crystal structure of 10-tert-butyl-1,8-dichloroanthracene (1). It was found that the level of deformation of the anthracene backbone continuously increases along the series of anthracene substituents SnMe3 < GeMe3 < SiMe3 < CMe3. Owing to the good agreement of experimental structural parameters with the results of quantum chemical calculations, the molecular deformations can be regarded as inherent molecular properties.