GAS-PHASE THERMOLYSIS OF PYRAZOLINES,3 - ELECTRONIC-STRUCTURE AND GAS-PHASE PYROLYSIS OF 4-SUBSTITUTED 3,5,5-TRIALKYL-3,5-DIHYDRO-4H-1,2,3-TRIAZOLES STUDIED BY PHOTOELECTRON-SPECTROSCOPY AND SEMIEMPIRICAL CALCULATIONS

The PE spectra of the 3,5-dihydro-4H-1,2,3-triazoles 1-3 have been rec orded. The ionization potentials have been assigned to molecular orbit als on the basis of MNDO, AM1, and PM3 calculations. The most importan t occupied MOs are characterized as pi(NNN), pi(C=X) (X = O, NCH3, CH2 ), n(N)-(3),n(NN)(+), n(NN)(-) and n(x). The gas-phase thermolyses of 1-3 have been studied by PE-controlled real-time gas analysis. After e xtrusion of molecular nitrogen, the remaining reactive species cyclize to three-membered rings. At higher temperatures and in flash vacuum p yrolysis, subsequent reactions lead to smaller acyclic compounds.