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T. Uchimaru, S. Tsuzuki, J. W. Storer, K. Tanabe, and K. Taira
[J. Org. Chem., Vol.59, pp.1835-1843, 1994]
Properties of various oxyphosphoranes such as neutral pentahydroxyphosphorane (doubly protonated 3b) and dianionic trihydroxyphosphorane (3b) and trimethoxy-phosphorane (3a) were examined by ab initio molecular orbital calculations. The energies of the stationary points were evaluated at the MP2 level of theory with the 6-31+G* basis. The analysis of the oxyphosphorane species indicates that the orientation of the equatorial methoxyl group determines the mode of formation/cleavage of the axial P-O2/P-O5 bond. This dependence of the reactivity on the conformation of the equatorial P-O3 bond is in accord with the prediction that is based on the stereoelectronic effect. However, the present work shows that the long-postulated "n-sigma* orbital interaction " is not predominant in the stereoelectronic control of the oxyphosphorane system.
