Benzoxaborolate ligands in group 13 metal complexes

A series of group 13 metal benzoxaborolates [R2MOB(o-CH2O)(C6H4)](2) [R = Bu-t, M = Al (2), R = Me, M = Ga (3), R = Bu-t, M = Ga (4), R = Bu-t, M = In (5)1 were synthesized in reactions of 1,3-dihydro-1-hydroxy-2,1-benzoxaborole (1) with group 13 metal trialkyls. The compounds were characterized by elemental analysis, melting point measurements, H-1, C-13 NMR, and IR spectroscopy. The molecular structure of 2-5 was determined by single-crystal X-ray diffraction. The structure of the compounds depends on the kind of metallic center. Reaction of (Bu3Al)-Bu-t with the benzoxaborole 1 leads to the aluminum derivative 2, similar to typical dialkylaluminum carboxylates, with a central eight-membered B2Al2O4 ring, in which two oxygen atoms of the benzoxaborolate unit are bonded to aluminum atoms. In the presence of gallium and indium trialkyls, the benzoxaborole 1 acts as an alcohol yielding complexes 3-5, similar to dialkylmetal alkoxides, with a central M2O2 (where M = Ga, In) ring. Thermal decomposition of compounds 2 and 4 revealed the liberation of a mixture of organoboron compounds. (C) 2013 Elsevier B.V. All rights reserved.