C-13, N-15 AND P-31 NMR INVESTIGATION OF P-SUBSTITUTED N-2,4,6-TRIS(TERT-BUTYL)-PHENYLIMINOPHOSPHINES

A large series of (E)- and (Z)-iminophosphines, Mes-N=P-X [X = NR(2), OR, Alk, Ar, SR, PR(2), Hal; Mes = 2,4,6-tris(tert-butyl)phenyl], wa s investigated by C-13, N-15 and P-31 NMR spectroscopy, The C-13 NMR c hemical shifts of methyl groups of the o-tert-butyl substituents, and also the carbon-phosphorus coupling of the meta- and para-carbons in t he aromatic moiety, were shown to be possible criteria for the assignm ent of the E- or Z-configuration of the iminophosphine. Basic rules ar e enumerated for the determination of configuration in the series cons idered. The variation of aromatic C-13 nuclei shielding is considered to be electrostatic (pi-inductive) in nature.