Structural and chemical studies relating to cyclotetramethylene trifluorophosphorane (1.1.1-trifluoro-λ 5P-phospholane)

Abstract

The title compound, (CH 2) 4PF 3, 1 holds a special position amongst stereochemically nonrigid fluorophosphoranes, due to the incorporation of λ 5P into a five-membered ring system; thus, 1 has served as a model in the rationalization of the mechanism of hydrolysis of cyclic phosphate esters (F.H. Westheimer, Acc. Chem. Res., 1 , 70 (1968)). Compound 1 , prepared by a new, efficient method, has been converted into two solid spiromonofluorophosphoranes, involving the λ 5P-phospholane ring system. Both in the gas phase (electron diffraction study of 1 ) and in the solid state (single crystal X-ray structure determination on two spiromonofluorophosphoranes) the (CH 2) 4 unit is bridging two equatorial positions at trigonal-bipyramidal λ 5P. The static and dynamic stereochemistry of 1 and of its derivatives will be discussed on the basis of the above structural studies as well as by n.m.r. spectroscopy. Some further derivative chemistry of 1 will be described.