t31P) and n.m.r. measurements on the triphosphazanes (Ph,P*NR),PPh show that J(PNP) is +280 Hz when R = Me and 25.1 Hz when R = Et. A similar marked dependence on the R groups has been found for the diphosphinoamines, Ph,P*NR*PPhCI (R = Me, Et, Pr", Pr', and But) (+334 to -35 Hz), and this may be related to the conformations about the P-N bonds, which are influenced by the stereochemical bulk of R. 1H-(31P) INDOR experiments on the symmetrical diphosphinoamines, Ph,P*NR*PPh, (R = Me, Et, and Pr'), indicate that J ( P N P ) is much greater when R = Me than when R = Et or Pr'.
Complementary information on these compounds has been obtained from lH, 13C, and l g F n.m.r., including double and triple resonance experiments. The coupling constant, ,J(PNP), covers the range -23.9 to 731.9 Hz, and its magnitude and sign can be related to the proportion of molecules in which the local symmetry of the P-N-P skeleton is C,, rather than C,. Diphosphinoamine conformers of the latter type have been clearly identified for the first time both in solution (for R = Et or Pr', X = Ph, and R = But or CH,But, X = CI) and also in the solid phase.X-Ray analysis of Ph,PN(Pr') PPh,, based on 1 269 diffractometric intensities refined to R = 0.035, shows that the symmetry of the P-N-P skeleton is close to C, in the solid, with P-N = 1.706(4) and 1.71 l ( 4 ) A, and PNP = 122.8(3)".
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