THE FORMATION OF MACROCYCLIC-COMPOUNDS CONTAINING 2 GA-GA BONDS BY THE REACTION OF TETRAALKYLDIGALLANE(4) R2GA-GAR2 [R = CH(SIME3)(2)] WITHDICARBOXYLIC-ACIDS

Tetrakis [bis(trimethylsilyl)methyl]digallane(4) 1 reacts with dicarbo xylic acids like 1,4-benzenedi(methylcarboxylic) acid, 1,4-cyclohexane dicarboxylic acid, 1,6-hexanedicarboxylic acid, and 1,4-butanedicarbox ylic acid (adipinic acid) by the release of two equivalents of bis(tri methylsilyl)methane and the retention of the Ga-Ga bond. Products are formed, in which the very short Ga-Ga bonds (237.7 pm on average) are bridged by two carboxylato groups. Two of these moieties are connected in each compound by two spacers (dimethylbenzene, cyclohexane, hexane , or butane) to form macrocyclic compounds with up to 22 atoms in the resultant heteroatomic rings. The dimeric form is also observed in sol ution. For comparison, the synthesis and structure of the product of t he reaction of 1 with 1-adamantanecarboxylic acid is included, which a lso has the Ga-Ga bond (239.1 pm) bridged by two carboxylato groups.