Matrix isolation investigation of the reaction of (CH3)3Al with O2

The matrix isolation technique has been employed to isolate and characterize the initial intermediate in the reaction of (CH,),AI with O-2. Using a flow gas reactor system immediately prior to matrix; deposition, evidence of reaction was noted only when a constricted nozzle was employed. Under these conditions, four product bands that can be assigned to a single product species were formed. Oxygen isotopic labeling and comparison with literature spectra identified the product species as monomeric (CH,)(2)A1OCH(3). Experimental and theoretical evidence are also presented to support the conclusion that (CH3)(3)A1OO is not the initial product of this reaction. Heating the deposition line to as high as 350 degrees C destroyed the initial bands and led to the formation of one or more secondary species. These could not be conclusively identified; the well-known dimer [(CH3)(2)AIOCH(3)](2) is the most likely candidate. The fact that the reaction only occurred with a constricted nozzle suggests that O-2 is reacting with the trimethylaluminum dimer, across the four-membered ring to form two molecules of (CH3)(2)A1OCH(3). (C) 1999 Elsevier Science S.A. All rights reserved.