THE REACTIONS OF R2GA-GAR2 AND R2IN-INR2 [R = CH(SIME3)(2)] WITH PROTIC REAGENTS - SUBSTITUENT EXCHANGE VERSUS CLEAVAGE OF THE ELEMENT-ELEMENT BOND

Tetrakis[bis(trimethylsilyl)methyl]digallane (1) with a Ga-Ga single b ond and the corresponding diindane(4) 2 with an In-In single bond were treated with different protic reagents: tert-Butyl alcohol did not re act with 1 at all, while phenol gave a mixture of unknown products, wh ich could not be separated. The more acidic pentafluorophenol did not react as an acid, but C-F bonds were cleaved to form almost quantitati vely the dimer (R2GaF)(2) 5, which was characterized by a crystal-stru cture determination. Water and 1 yielded the dimeric dialkylgallium hy droxide 6. The Ga-Ga bond was also cleaved by the reaction of 1 with d urylthiophenol (duryl = 2,3,5,6-tetramethylphenyl), which gave two mai n products: R2Ga(SDuryl) 7 and RGa(SDuryl)(2) 8. In contrast, the chel ating acid dibenzoylmethane reacted by means of a substituent exchange , with the release of two equiv. of bis(trimethylsilyl)methane for eac h formula unit of 1, to form 9, in which the Ga-Ga bond is retained an d each chelating 1,3-diphenyl-1 ,3-propanedionato ligand is in a termi nal position bonded to only one Ga atom, in more than 80% yield. The G a-Ga bond is shortened [244.1(1) pm] compared to that in the starting compound tetraalkyldigallane(4) 1. The In-In bond of diindane(4) 2 is, however, cleaved in a similar reaction with dibenzoylmethane, and onl y the fragmentation product dialkyl(1,3-diphenyl-1,3-propanedionato) 1 0 could be isolated.