A quantum mechanical semiempirical interpretation of the electronic spectrum and the gas phase U.V. photoelectron spectrum of hemiporphyrazine

Quantum Mechanical semiempirical computations (PPP, HAM3) have been performed on the macrocycle Hemiporphyrazine. The electronic spectrum is well interpreted on the basis of PPP calculations, the ionization energies obtained by the Photoelectron Spectrum are also well reproduced by the HAM3 results

Gas-phase Basicity and Ionization Energies In Some N-arylazacycloalkanes

Proton-transfer equil. const. and ionization energy measurements were performed in the gas phase for N-arylazacycloalkanes. The techniques used were Fourier transform ion cyclotron resonance and UPS. The aim was to clarify peculiar aspects of the reactivity in soln. of these cyclic mols., for instance, the significant difference in the velocity of the ring-opening reaction between 3- and 4-membered rings. This difference is mainly related to intrinsic structural and electronic parameters; environmental factors (i.e., solvation, ion pairing, etc.) play only a minor role

Ring-size effects on the ionization potentials of N-substituted azacycloalkanes

The ionization potential of the lone-pair electrons of nitrogen has been determined for N-methyl- and N-tosyl-azacycloalkanes by means of gas-phase u.v. photoelectron spectroscopy. The cyclic compounds examined contain small, common, medium, and large-membered rings. The ionization potentials are affected by conformational features and, in particular, by the strain present in the ring. More precisely, the IPs reflect changes of hybridization of the nitrogen Ione pair upon varying the ring size, whereby a lower or higher energy is required for the ionization process of the cyclic compounds relative to a series of open-chain alkyl amines taken as reference. Steric inhibition of resonance by the N-tosyl substituent takes place in the case of the strained small rings