STRUCTURAL CORRELATIONS IN SMALL MOLECULES - SIMPLE MOLECULAR-ORBITAL TREATMENT OF SP MIXING

Simple molecular orbital theory in the form of the angular-overlap model is used to assess the changes in bond stabilization energy as a result of sp mixing as the angular geometry of a molecule changes. The results reproduce well qualitative aspects of the observed bond shortenings and elongations (described by Bürgi, Dunitz, Murray-Rust, and colleagues) in C3v, C2v, and D2d MX4 molecules compared to Td, C2v MX3 molecules compared to D}h, and C3„ MX5 molecules compared to D3h. A study of the Berry process highlights differences between five-coordinate transition-metal and main-group systems. A hierarchy of perturbations causing structural change is described. © 1979, American Chemical Society. All rights reserved.