Theoretical Study on the Structures of Iminopnictoranes and Their Reactions with Formaldehyde

Abstract

The geometries and energies of the iminopnictoranes (H3MNH; M = P, As, Sb, and Bi) and their reaction paths with formaldehyde are predicted by means of ab initio calculations. The multiplicity of MN bonds is discussed by comparing the MN and M−H bond lengths, the bond length ratios MN:M−N, the bond angles of M−N−H, and the barrier to internal rotation about the MN bond with those of the ylides, and it was concluded that the contribution of the ionic canonical form M+−N- is much more important than that of the MN form. For the two reaction routes of the iminopnictoranes with formaldehyde (aza-Wittig and Corey−Chaykovsky-type reactions), all of the stationary points and transition states were fully optimized by using an analytical gradient with the LANL1DZ and the 9s5p-d/[3s2p-d] basis set (DZ-d) at the MP2 level. For M = P and As, the aza-Wittig reaction is more favorable than the Corey−Chaykovsky-type reaction from both the thermodynamic and the kinetic viewpoint. In the case of M = Sb and Bi, the Corey−Chaykovsky-type reaction takes place predominantly. The higher level calculations, such as MP4(SDTQ)/DZ-d//MP2/DZ-d and QCISD(T)/DZ-d//MP2/DZ-d, were performed to get accurate energies of these intermediates and transition states.

Superbasic properties of the SN functional group

“…For the other nitrogen bases (H 2 C=NH, HN=NH and H 3 P=NH), there is no doubt that the N-imino atom is first protonated in the gas phase. 15,[19][20][21][22] The results obtained for H 2 C=NH were compared with those found by experiment. 15…”

The Chemistry of Phosphazenes. Synthetic Applications of Cα-Lithiated Derivatives

“…Neilson and Wisian-Neilson have developed a variant of the Kirsanov reaction, giving access to P-(halo)(N-trimethylsilyl)phosphazenes (8). Theoretical studies on the model compound H 3 PNH at levels MP2/DZ-d [15], MP2/6-31G* [16], MP2/6-31G** [17] led to a similar picture for describing the PN bond properties. 3, Scheme 2 ).…”

“…For simplicity, the PN moiety of phosphazenes is drawn as a conventional phosphorus-nitrogen double bond. For the H 3 PNH model phosphazene, the magnitude of the barrier increased to 2.13 kcal mol -1 and 2.54 kcal mol -1 when the theory level was RHF/6-31G* [16b] and MP2/DZ-d [15], respectively. Theoretical studies on the model compound H 3 PNH at levels MP2/DZ-d [15], MP2/6-31G* [16], MP2/6-31G** [17] led to a similar picture for describing the PN bond properties.…”

Computational Study of the Substitution Effect on the Mechanism for the Aza‐ and Arsa‐Wittig Reactions

“…1,[6][7][8][9][10][11] Recently, several theoretical studies on the mechanism of the aza-Wittig reaction have been provided. 3,[12][13][14][15] We have provided the first computational report on the mechanism for the phospha-Wittig reaction. 16 However, to the best of our knowledge, this is the first computational report concerning a systematic study of the substitution effect on the mechanism for the arsa-Wittig reaction based on the more sophisticated theory.…”