TRIS-DIMETHYLAMINOPHOSPHORUS REACTIONS AT LOW-PRESSURE ON GAP, INP AND QUARTZ SURFACES

The decomposition of the phosphorus precursor tris-dimethylaminophosph orus (TDMAP), at low pressures (similar to 10(-4) Torr) has been studi ed by mass spectrometry. Three different surfaces were used: quartz, I nP and GaP. For the three surfaces pyrolysis is 50% complete at approx imately 820, 520 and 350 degrees C, respectively. The activation energ y for decomposition on the GaP surface is 18.5 +/- 2.5 kcal/mol and fo r the quartz surface, 47.3 +/- 3.5 kca/mol. The principle reaction pro ducts are dimethylamine, methylmethyleneimine and methyleneimine. On t he quartz surface decomposition appears to occur via homolysis of the parent molecule, producing dimethylaminyl radicals, which react subseq uently to form the observed products. For the surface-catalyzed reacti ons an intramolecular reaction mechanism is proposed in which there is a transfer of a hydrogen atom from a methyl group to the nitrogen lon e-pair on an adjacent ligand. This reaction would produce both dimethy lamine and methylmethyleneimine.