Ab Initio Calculations on Phosphorus Compounds. II. Effects of Disubstitution on Ligand Apicophilicity in Phosphoranes


Geometry optimizations at the HF/3-21G(*) and HF/6-31G* levels of ab initio theory have been carried out for various isomers of model disubstituted phosphoranes PH3XY(X, Y═OH, CH3, NH2, and SH). Reasonable agreement was obtained between the optimized geometries and available crystal structure data for analogous compounds. The isomers were further characterized by frequency calculations. The MP2/6-31G*//6-31G* + ZPE energy data reveal that the interactions between the ligands are relatively small (0-4 kcal mol-1) for the most stable conformations of the isomers. Hence, for these conformations the apicophilicities (based upon monosubstituted phosphoranes) are approximately additive. The less stable PH3XY conformations are in general transition states or higher-order saddle points, and their interligand interactions are larger in magnitude (up to 10 kcal mol-1); the results with these conformations suggest that apicophilicities may not be as additive for some highly substituted phosphoranes.



Keywords and Phrases

Crystal Structure; Isomers; Ligands; Phosphorus Compounds; Ab Initio Calculations; Ab Initio Theory; Crystal Structure Data; Frequency Calculations; Geometry Optimization; Optimized Geometries; Saddle Point; Transition State; Calculations

International Standard Serial Number (ISSN)

0192-8651; 1096-987X

Document Type

Article - Journal

Document Version


File Type





© 1993 Wiley-Blackwell, All rights reserved.

Publication Date

01 May 1993