Formation of cyclophosph(III)azanes and their oxo- and thioxo-derivatives

Abstract

The reactions of phosphorus trichloride with three molar equivalents of methylamine and ethylamine give bis-(dichlarophosphino)amines (Cl₂P)₂NR (R = Me and Et), and with isopropylamine and t-butylamine, cyclodi-phosph(III)azans, (ClPNR)₂(R = Pr^I and Bu^t) are obtained as major products. There is mass spectroscopic evidence for the cyclophosph(III)azans, (ClPNEt)_n(n= 2 or 3) in the products from the reaction with ethylamine, but these compounds have not been obtained pure. Several other potential routes to N-methylcydophosph(III)azanes were examined, inculding the reaction of phosphorus trichloride or of bis(dichlorophosphino)methylamine, (Cl₂P)₂NMe, with heptamethyldisilazane, (Me₃Si)₂NMe, which gave the dichiorophosphinamines, Cl₂P·NMe·SiMe₃(Cl₂P)₂NMe, and the cage compound P₄(NMe)₆, but no compounds of the type (ClPNMe)_nwere obtained. Similarly, dichloroaiylphosphines and hepiamcthyldisilazane gave the phosphinamines ClArP·NMe·SiMe₃ and (ClArP)₂NMe (Ar = Ph or C₆H₄-p-Me). m-Chtoroaniline hydrochloride reacts with phosphorus trichloride affording (Cl₂P)₂NC₆H₄-m-Cl, which with SbF₃produces (F₂P)₂NC₆H₄-m-Cl. (Cl₂P)₂NPh and the analogous fluoride were obtained similarly. The cyclodiphosph(III)azanes, (ClPNR)₂(R = Pr^I or Bu^t), gave monoxides and monsulphides containing P^III and P^V atoms within the ring system, on reaction with dimethyl sulphoxide and elemental sulphur respectively. Oxothioxocyclodiphosphazanes were obtained by a related route. The ¹H and ³¹P n.m.r. spectra of these compounds are reported and discussed.