A LINEAR CORRELATION OF PROTON CHEMICAL SHIFTS IN SOME ALKYL CHLORIDES AND HYDROCARBONS WITH THE OCCUPATION NUMBER OF THE HYDROGEN ORBITALS

A linear correlation exists between the proton shifts of some alkyl chlorides and some hydrocarbons and the occupation numbers of the hydrogen 1s orbitals in the C—H bonds. The occupation numbers are those given by the self-consistent group orbital and bond electronegativity method. The application of this correlation to the prediction of starting values for occupation numbers, to the derivation of bond anisotropies in ethylene and acetylene, and to the prediction of hydrogen-bonded shifts of C—H protons is discussed.

IONIZATION POTENTIALS OF METHYL-SUBSTITUTED BENZENES AND CYCLOPENTADIENES

The ionization potentials of a number of methyl-substituted benzenes and cyclopentadienes have been measured by electron impact. The experimental results are compared to calculations based on a group orbital method.

A GROUP ORBITAL STUDY OF LITHIUM HYDRIDE

A quantum mechanical treatment of lithium hydride in the group orbital approximation is presented. Some excited states and an improved ground state are obtained by means of configuration interaction within a single group.The total energy obtained for the ground state at several interatomic distances (R = 2.0–8.0 a.u.) omitting and including configuration interaction and for the first excited singlet state compare very well with the values reported by Karo in a comparable simple molecular orbital calculation.The chemical significance of the group orbital method is discussed. The results of the present calculations are related to some chemical reaction mechanisms and to some spectroscopic phenomena.