The title compounds of the type P(RNCH2CH2)3N (1, R = H; 2, R = Me; 3, R = CHz2Ph) display the unexpected basicity trend 1 < 2 < 3 with respect to protonation which forms the azaphosphatranes magnified image (4, R = H; 5, R = Me; 6, R = CH2Ph). The unusual basicity order 1 < 2 < 3 is also supported by the trend in 1JPSe values obtained for SeP(RNCH2CH2)3N (8, R = H; 9, R = CH2Ph; 10, R = Me). Deprotonation of 4 is shown to produce a variety of deprotonated derivatives which were trapped by alkylation with MeI. A favored rationale for the unusual weakness of 4 as a protonic acid (pKa in DMSO, 29.6) is an unusual stability of the axial three‐center four‐electron bond signalled by the unusually high field 31P chemical shift of this cation (—42 ppm).
No takes yet. Share an insight, caveat, or question.
Laramay et al. (1991) studied this question.