Synthesis of aryloxyaluminium hydrides and their conversion into aryloxyalumoxanes (ArOAlO)n

Abstract

The reaction of bulky phenols with H3Al·NMe3 afforded the new primary phenoxyalanes Mes*OAlH2· NMe3, 2 (Mes* = 2,4,6-tBu3-C 6H2-), 2,6-Dipp2C6H 3OAlH2·NMe3, 3 (Dipp = 2,6- iPr2C6H3-), and 2,6-Trip 2C6H3OAlH2·NMe3, 4 (Trip = 2,4,6-iPr3C6H2-) as colorless crystalline solids. Subsequent reactions of 2,6-tBu 2-4-MeC6H2OAlH2·NMe 3, 1, and 2 with oxygen sources such as (Me2HSi) 2O or Me2SO gave the disiloxyalane 2,6-tBu 2-4-Me-C6H2OAl(OSiHMe2) 2·NMe3, 5, and the alumoxane (Mes*OAlO·OSMe2)4, 6. The latter compound is a rare example of a species featuring an unsupported eight-membered (Al-O)4 ring. The new compounds were characterized by 1H and 13C{1H} NMR and IR spectroscopy and elemental analyses, and compounds 3 and 6 were also characterized by single crystal X-ray diffraction. © 2009 The Royal Society of Chemistry.