Synthesis, molecular structure and biological activity of bromobenzylgermatranes

The new series of benzylgermatranes , R=H ( I ), 2-Br ( II ), 3-Br ( III ), 4-Br ( IV ), has been obtained to study the influence of a substituent position on coordination of the germanium atom, the values of bond angles and neurotropic activity. Compounds I – IV were prepared by insertion of GeBr 2 into carbon–bromine bond of the corresponding benzylbromide or bromobenzylbromide in refluxing toluene, conversion of benzyl- or bromobenzyltribromogermanes into triethoxy derivatives by alcoholysis, and transalkoxylation with triethanolamine. The crystal structure of compounds I – IV was studied via the X-ray diffraction method. The intramolecular donor–acceptor bond N→Ge in benzylgermatranes (2.175–2.219 A) is shorter than that in tolylgermatranes (2.212–2.230 A). Biological investigations have demonstrated that all benzylgermatranes ( I – IV) are low toxic compounds (LD 50 >1000 mg kg −1 ) with high anaesthetic and anti-Corazol activity. Benzylgermatrane ( I ), 3-bromobenzylgermatrane ( III ) and 4-bromobenzylgermatrane ( IV ) improve memory processes and completely prevent animals from retrogradal amnesia (RA) caused by electroshock.