Diverse reactivity of dialkylaluminum dimesitylboryloxides [(mu-Mes(2)BO)AlR2](2). Synthetic and structural study

Several stable dimeric dialkylaluminum boryloxides of the formula [(mu -Mes (2)BO)AlR2](2) (R = Me (1), Et (2),Bu-1) have been prepared from dimesitylb orinic acid Mes(2)BOH and trialkylaluminums R3Al. Compound 1 has been chara cterized by X-ray diffraction. These compounds exhibit diverse reactivity t oward protonolytic reagents depending on the bulkiness of these reagents. T reatment of 1 with tert-butyl alcohol afforded crystalline species trans-[( mu-(BuO)-Bu-t)(Mes(2)BO)AlMe](2) (3), which is the first example of a mixed system containing boryloxide and alkoxide ligands together. Most surprisin gly, Mes(2)BOH was found to undergo catalytic decomposition in the presence of [(mu -Mes(2)BO)AlR2](2) via the unexpected cleavage of one boron-carbon bond. The molecular structure of the decomposition product, i.e., trimesit ylboroxin [MesBO](3) (4) is reported.