Adiabatic ionisation energies were computed with the composite method G4, IE/eV = 27.2116 × {G4(0 K)[cation] -G4(0 K)[neutral]} which has been shown to perform adequately. There is good agreement with the results of the Kaiser group 13 except for the cyclics 1,3-oxazetidine and 3-methyl-oxaziridine which have been mis-tabulated 89 as 9.43 and 9.02 eV, respectively, instead of 9.02 and 9.43 eV, see Table , and for methyleneamino-methanol which can be rationalised because here the lowest energy conformer with ∠ CNCO = 0 • is considered as opposed to what is probably a gauche conformer.