Crystal and molecular structure of trans-3,4-dihydro-2,3,4-triphenyl-5-phenylmethyl-2H-1,2,3-diazaphosphole 3-oxide

Abstract

The crystal and molecular structure of the first reported example of a new five-membered cyclic diazaphospholene oxide was solved by X-ray crystallographic techniques. This compound crystallizes in space group P with unit-cell dimensions a= 5.815(2), b= 9.688(4), c= 20.207(9)Å, α= 95.47(6), β= 95.04(4), γ= 89.32(4)°, with Z= 2. The five-membered ring is an irregular and almost planar pentagon. The geometry about the phosphorus atom is that of a distorted tetrahedron with angles ranging from 91 to 118°. The formation of a trigonal bipyramidal phosphorane intermediate by addition of nucleophiles at the face opposite to the P–N bond involves relatively small additional bond-angle deformations: this factor may explain the reactivity of this new heterocyclic system toward nucleophiles.