Cyclisation of bis(dichlorophosphino)-, bis(dichlorophosphinoyl)-, and bis(dichlorophosphinothioyl)-amines by primary amines

Abstract

The compounds [Cl₂P(X)]₂NR (IIIa, X = lone pair, R = Me, Et, or Bu^t; IIIb, X = O, R = Me or Et; IIIc, X = S, R = Me) react with 3 mol equiv. of t-butylamine to give cyclodiphosphazanes Cl(X)[graphic omitted]Bu^t, (V). Preparation of the long-sought cyclophosph(III)azanes (ClPNR)_n(R = Me or Et) from (IIIa) has also been attempted by the same route, and new n.m.r. and mass-spectroscopic evidence has been obtained for formation of these derivatives (n= 3 and 4, R = Me; n= 2 and 3, R = Et), but no pure products have been isolated. Only when X = O and R = Me or Et could evidence for the formation of derivatives Cl₂P(X)·NR·P(X)Cl·N(H)Bu^t, (II), be obtained, and possible reasons for the rapid cyclisation step involved are discussed. The known derivative Cl₂P(O)·NMe·P(O)Cl·N(H)Me, (IIb), was readily cyclised by t-butylamine to give [ClP(O)·NMe]₂, (Ib). Phosphoryl chloride reacts with 3 mol equiv. of primary amines to give mixtures of the derivatives Cl₂P(O)·N(H)R (R = Me, Et, Prⁱ, or Bu^t) and ClP(O)[N(H)R]₂(R = Me, Et, or Prⁱ), rather than cyclodiphosphazanes as obtained in analogous reactions with phosphorus trichloride.