Disodium tetrasupersilyltetragallanediide Na2Ga4R*4.2THF (R* = SitBu3). Preparation of a novel gallium cluster compound via dichlorodisupersilyldigallane R*2Ga2Cl2

Red tetragallanediide Na2Ga4R4.2THF (R = SitBu3) was prepd. by redn. of the monogallane RGaCl2.THF in heptane or the tetrahedro-tetragallane R4Ga4 in benzene/THF with sodium at 100 Deg. Potassium worked analogously as a redn. agent. As an intermediate of the dehalogenation of RGaCl2.THF, the orange digallane R2Ga2Cl2 and the dark violet tetrahedrane R4Ga4 were formed. The extreme air- and moisture-sensitive Na2Ga4R4.2THF was stable against Me3SiCl, but reacted with oxygen with formation of R4Ga4, and with GaBr forming several products (isolation and x-ray structure anal. of RGaBr2.THF). According to x-ray structure analyses, (i) the tetragallanediide contains a nonplanar Ga4 ring with short Ga-Ga bonds, whereby three Ga atoms on opposite sides of the ring are each connected with one of the two Na(THF) groups, (ii) the digallane is dimeric, whereby it takes the structure of As4S4 (exchange of As/S against Ga/Cl). The possible ways of RGaCl2.THF redn. are discussed, an explanation of the structure of Na2Ga4R4.2THF is given, and other previously prepd. halides RnEnHal2 (E = Al-Tl) are compared. [on SciFinder (R)]