Modified Valence-Bond Treatment of Unsaturated and Aromatic Compounds

Abstract

The conventional valence‐bond treatment, by being put upon a more frankly empirical basis, can be modified in such a way that the difficulties arising from the nonorthogonality of the atomic orbitals centered about different atoms are largely bypassed. Although the extension of the new treatment to molecules more complex than that of benzene is rendered impracticable by the increased mathematical difficulties, the results obtained for 1,3‐butadiene, cyclobutadiene, and benzene suggest that many of the essential features of the older calculations can be given a better theoretical justification than hitherto seemed possible. On the other hand, the importance of the relatively unstable structures with formal bonds appears to have been overrated.