Electronic Structures of Polyatomic Molecules. VII. Ammonia and Water Type Molecules and Their Derivatives

Abstract

Spectroscopic and ionization potential data are used in obtaining electron configurations in terms of molecular orbitals for NH3, PH3, H2O, H2S and their derivatives, e.g., CH3NH2, (CH3)2NH, N2H4, H2O2, CH3OH, NH2Cl, ClOH, Cl2O. These electron configurations hold for molecules in their normal states, but can be used in predicting the energy of ``vertically'' excited states, i.e., energies corresponding to nuclear dimensions the same as for the normal state. Frequent close similarities between the spectra of parent molecules and their derivatives are explained (also the similarities between alkyl halides such as CH3I, C2H5I, etc.). Estimates of vertical ionization potentials for the various orbitals used are given. Various points (types of orbitals used, Rydberg series, predissociation) are touched on. The longest wavelength ultraviolet spectra and minimum ionization potential are attributed in the NH3 derivatives to excitation of a nearly nonbonding electron of the N atom, in the H2O and H2S derivatives to excitation of a nonbonding O or S atom electron. (Exception: compounds containing I, Br, and perhaps Cl, where the halogen atom supplies the most easily excited and ionized electron.)