SYNTHESIS, X-RAY GEOMETRY, AND ANODIC BEHAVIOR OF TRIS[2-(HYDROXYMETHYL)PHENYL]PHOSPHANE

Tris[(monohydroxymethyl)phenyl]phosphane 5a and 5b were prepared, and the geometry of the ortho-isomer 5a was determined by X-ray diffractio n. 5a was found to be propeller-like in shape, exhibiting a helical co nformation with the three hydroxymethyl substituents standing on the s ame side as that with the phosphorus lone pair. Phosphanes 5a and 5b u nderwent electrochemical one-electron oxidation, giving rise to nonper sistent phosphoniumyl cation radicals 5a(.+) and 5b(.+). The low value of the anodic peak potential of 5a was explained by the fast decay of 5a(.+), which was rapidly rearranged to a phosphoranyl radical throug h the formation of a strong P-.-O bond. The fast oxidation of this int ermediate phosphoranyl radical followed by a second cyclization led to the ymethyl)phenyl]spirobi[1H,3H-2,1-benzoxaphosphole] 7a, which was isolated in significant yield.