A second polymorphic form of N,N'-diphenyl-1,4-phenylenediamine

(6E)-N-[(4Z)-2,5-Dimethyl-4-(p-tolyl-imino)cyclo-hexa-2,5-dienyl-idene]-4-methyl-aniline

The title compound, C(22)H(22)N(2), was prepared by the reaction of 4-amino-toluene with sodium carbonate, sodium hydroxide and potassium permanganate. The mol-ecule is disposed about a crystallographic inversion centre with one half-mol-ecule comprising the asymmetric unit. The dihedral angle between the terminal and central benzene rings is 88.05 (1)°. The crystal packing is stabilized by van der Waals forces.

Methylene-azaphosphirane as a reactive intermediate

Reaction of the transient phosphinidene complexes R-P=W(CO)5 with N-substituted-diphenylketenimines leads unexpectedly to the novel 2-aminophosphindoles, as confirmed by an X-ray crystal structure determined for one of the derivatives. Experimental evidence for a methylene-azaphosphirane intermediate was found by using the iron-complexed phosphinidene iPr2N-P=Fe(CO)4, which affords the 2-aminophosphindole together with the novel methylene-2,3-dihydro-1H-benzo[1,3]azaphosphole. Analysis of the reaction pathways with DFT indicates that the initially formed methylene-azaphosphirane yields both phosphorus heterocycles by way of a [1,5]- or [1,3]-sigmatropic shift, respectively, followed by a H-shift. Strain underlies both rearrangements, which causes these remarkably selective conversions that can be tuned by changing the substituents.