title: The reactions of dialkylgallium hydrides with tert-butylethynylbenzenes--a systematic investigation into the course of hydrogallation reactions.
abstract: The reactions of bis- and tris(tert-butylethynyl)benzenes with dialkylgallium hydrides afforded two different types of products. 1,4-Di(tert-butylethynyl)benzene and dialkylgallium hydrides R(2)GaH bearing relatively small substituents (R = Et, nPr) gave the expected addition products with each C triple bond C triple bond inserted into a Ga-H bond. The intact GaR(2) groups are attached to those carbon atoms which are in alpha-position to the benzene rings, and intermolecular Ga-C interactions led to the formation of one-dimensional coordination polymers. In contrast secondary reactions with the release of the corresponding trialkylgallium derivatives GaR(3) (R = Et, nPr, iPr, CH(2)tBu, tBu) were observed for all hydrogallation reactions involving the trisalkyne 1,3,5-tris(tert-butylethynyl)benzene. A similar reaction was observed upon treatment of the 1,4-bisalkyne with a dialkylgallium hydride bearing a relatively bulky substituent (R = neopentyl). Cyclophane type molecules are formed in all these cases with two or three gallium atoms in the bridging positions between both benzene rings.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Universität Münster, D-48149, Münster, Germany. uhlw@uni-muenster.de
authors.forename: Werner
authors.initials: W
authors.lastname: Uhl
authors.forename: Michael
authors.initials: M
authors.lastname: Claesener
authors.forename: Sima
authors.initials: S
authors.lastname: Haddadpour
authors.forename: Beate
authors.initials: B
authors.lastname: Jasper
authors.forename: Alexander
authors.initials: A
authors.lastname: Hepp