Synthesis of Boroxine-Linked Aluminum Complexes

The reaction of LAlH2 (L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) (1) with 3-methylphenylboronic acid and 3-fluorophenylboronic acid resulted in the boroxine-linked aluminum compounds LAl[OB(3-CH3C6H4)]2(μ-O) (2) and LAl[OB(3-FC6H4)]2(μ-O) (3), respectively. LAl[OB(2-PhC6H4)(OH)]2 (4) was synthesized by the reaction of 1 with 2-biphenylboronic acid. Compound 4 is the intermediate analogue to those, which we postulated for the formation of 2 and 3. The reaction of 1 with 3-hydroxyphenylboronic acid resulted in the first metal benzoboroxole oxide LAl[OB(o-CH2O)C6H4]2 (5), which is formed from a compound with B−(OH)2 and C−OH functionalities.