Structure of Oxyphosphoranes from X-Ray Analysis

Molecular Structure of Oxyphosphoranes from, X-Ray Analysis 1. Five-membered oxyphosphoranes 

The reaction of trialkyl phosphites with oriAo-quinones produces cyclic pentaoxyphosphoranes suitable for X-ray analysis. One of these 

Bond Lengths and Angles in a Five-Membered Cyclic Unsaturated Pentaoxyphosphorane 

signal 8 =49-2 p.p.m. (upheld relative to HsP04). The model constructed from these data is reproduced in Fig. 1. The phospholene ring occupies an apical-equatorial position. The apical bonds are longer than the corresponding equatorial bonds. The apical P—0(1) bond 

A rather striking example of the stability conferred to TBP-phosphorus by the presence of some rings is provided by the phosphorus heterooycle 

---