A 19F NMR study of electronic effects in iminophosphoranes and in their methyl iodide salts

¹⁹F NMR shifts have been obtained for the iminophosphoranes(FC₆H₄)_n(C₆H₅)_3?nPNC₆H₄X(n = 1, 3) and (XC₆H₄)₃ PNC₆H₄F and for their methyl iodide salts. The data for the iminophosphoranes indicate the presence of a polar PN bond, considerable electron delocalization from nitrogen to the attached aryl ring, and a modest degree of arly-phosphorus conjugative interaction. In the salts the delocalization of the electron pair of nitrogen is largely curtailed.