Synthesis and molecular structure of phenyl and tolylgermatranes

The crystals of arylgermatranes R-C6H4-Ge(OCH2CH2)(3)N (R = H (I), 4-CH3 (II), 3-CH3 (III), 2-CH3 (IV)), have been obtained to stu dy the influence of a substituent position on coordination of the germanium atom. Compounds I-IV were prepared by the insertion of GeBr2 into the carb on-bromine bond of the corresponding arylbromide, conversion of aryltribrom ogermanes to triethoxy derivatives by alcoholysis and their transalkoxylati on with triethanolamine to germatranes; or by the condensation of halobenze ne with GeCl4 in the presence of copper powder followed by alcoholysis and cyclization. The crystal structure of compounds I-IV was studied via the X- ray diffraction method. The intramolecular donor-acceptor bond Ge <-- N in arylgermatranes (2.212-2.230 Angstrom) is longer than that in the correspon ding furyl- and thienylgermatranes. Introduction of a substituent into o-po sition of the benzene ring decreases the N-Ge-C angle value from 177.5 to 1 44.2 degrees. The quantum chemical calculations were performed to investiga te structures I-IV in isolated molecules. (C) 1999 Elsevier Science S.A. Al l rights reserved.