Structurally characterized new alkyl- and alkenyl-gallium peroxides having interesting structural motifs

Abstract

Reaction of lithium gallium hydride, LiGaH4, with one equivalent of tert-butyllithium generated lithium(tert-butyl)trihydridogallate, Li[tBuGaH3] (1), as colorless solid via LiH elimination. Treatment of 1 with four equivalents of tert-butyl hydrogenperoxide and subsequent crystallization generated few colorless crystals at -35 °C. Single crystal X-ray diffraction study showed the formation of a (tert butyl) galliumperoxide [tBu-Ga(OOtBu)2O(H)-Li(HOtBu)2]2 (2) where a strongly reducing “tBu-Ga” group is situated intact to two strongly oxidizing “Ga-O-O-tBu” moieties. Further, two such alkyl-galliumperoxo units dimerizes through hydroxolithium bridges. A close look at the single crystal X-ray structure of 2 show the presence of strong hydrogen bonding interactions between the peroxide oxygen and hydroxy group of tert-butanol, which are coordinated to the lithium ions. Similarly, the first alkenyl-gallium peroxide was generated via reaction of [Ph-CH=C(SiMe3)GaH2tBuLi] (3) with three equivalent of tert-butyl hydrogen peroxide. Single crystal X-ray diffraction study showed the formation of an alkenyl-gallium peroxide [Ph-CH=C(SiMe3)Ga(OOtBu)3Li]2 (4) via elimination of two equivalents of hydrogen and one equivalent of isobutane where three tert-butylperoxo groups along with an alkenyl group are attached concurrently to a single gallium atom. In addition, each of the lithium atoms are coordinated with four different oxygen atoms of two different peroxide groups.