Molecular electrostatic potentials and electron densities in azatriprismanes and nitroazatriprismanes

Triprismane, a C6H6 isomer of benzene, belongs to a class of strained hydrocarbons. In this work, the energy and charge distributions in a series of aza (C6N,H6-alpha) and nitroaza (CNO2)(6-alpha)N-alpha, (with alpha = 1...6) derivatives of triprismane have been analyzed using the ab initio Hartree-Fock (HF)-derived molecular electrostatic potentials and molecular electron densities. Electrostatic potential investigations have shown that the electron-rich regions around nitrogen along a series of azatriprismanes and those near oxygens of nitro group in nitroazatriprismanes become smaller on encompassing from the hexanitroaza to nitroazatriprismane. As revealed from the molecular electrostatic potential (MESP) topography for the series of azatriprismanes the MESP minimum near nitrogen become shallow with increasing nitrogen content. Heats of formation obtained from the isodesmic reaction approach in the C6N6H6-alpha and (CNO2)(6-alpha)N-alpha series correlate well with the electron density at the bond-critical point of the X-N (X = C or N) bonds of the triprismane framework.