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 GeBr2 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 Å) is shorter than that in tolylgermatranes (2.212–2.230 Å). Biological investigations have demonstrated that all benzylgermatranes (I–IV) are low toxic compounds (LD50>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.