peri-Interactions in Naphthalenes, 10 [1]. In Search of Independent Criteria for N→P Bonding: Protonation Studies on (8-Diethylamino-naphth-1-yl)-diphenyl-phosphine

Enhancement of the basicity of the amino group in (8-dialkylamino-naphth-1-yl)-diphenylphosphines diverts protonation from the P to the N atom. Thus the cation 8-Et (H)-C -PPh becomes available whose H and P NMR spectra provide arguments against dative N→P interactions in the phosphines and their quaternary phosphonium salts. Likewise, the X-ray structure of 8-Et N-C -PPh does not indicate such interactions.