Reducing Ga-H and Ga-C bonds in close proximity to oxidizing peroxo groups: conflicting properties in single molecules.
Treatment of [Li(H(2)Ga{CH(SiMe(3))(2)}(2))]2 OEt(2) (12 OEt(2)) with two equivalents of tert-butyl hydrogen peroxide, H-O-O-CMe(3), afforded the organogallium peroxide [({(Me(3)Si)(2)HC}(2)Ga(OH)(OOCMe(3))Li)(2)] (3), which possesses oxidizing peroxo groups in close proximity to reducing Ga-C bonds. The lithium atoms of the dimeric formula units are coordinated by both oxygen atoms of the peroxides and by two hydroxo groups. The cleavage of the Ga--C bond was not observed, even when an excess of H-O-O-CMe(3) was applied. Instead, the adduct [{(Me(3)Si)(2)HC}(2)Ga(OH)(OOCMe(3))(2)Li(2)(HOOCMe(3))] (4) was isolated, which has an intact H-O-O-CMe(3) molecule terminally attached to lithium. A similar structural motif was found for the compound [(LiOOCMe(3))(2)(HOOCMe(3))(2)] (5). The trihydrido gallanate [Li(H(3)Ga-{CH(SiMe(3))(2)})]OEt(2) (2) yielded the unique peroxide [({(Me(3)Si)(2)HC}--Ga(H)(OOCMe(3))(2)Li)(2)] (6) under similar conditions that possesses Ga-C and even more reactive Ga-H bonds beside peroxo groups. It decomposed at room temperature by the insertion of oxygen atoms into the Ga-H bonds and the formation of [({(Me(3)Si)(2)HC}-Ga(OH)(OCMe(3))(OOCMe(3))Li)(2)] (7), which was isolated in a low yield. Further decomposition gave the complete degradation of all peroxo groups with the formation of a relatively complicated Li(4)Ga(4)O(8) cage (8).
Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany. uhlw@uni-muenster.de
Werner
W
Uhl
Mohammad
M
Reza Halvagar
Michael
M
Claesener