Orbital interaction in amino-ketones

Abstract

A study of the orbitals of a-aminoacetone and a-aminoacetaldehyde as a function of the two important torsions in these molecules is reported. The individual level shifts are much greater than the variation of the total energy. We identify four significant interactions affecting the level ordering. Each interaction has its distinctive conformational dependence. In order of decreasing spectroscopic importance the interactions are as follows.(1) Through bond coupling of the nitrogen and oxygen lone-pairs. (2) Through space interaction of these lonepairs. (3) Hyperconjugation between the C-N G* level and the carbonyl x-system. (4) Direct overlap of the nitrogen lone-pair with the carbonyl x-system.OUR continuing interest in the interaction of orbitals through space and through bonds prompted us to examine the electronic structure of a series of a-substituted carbonyl compounds (1). This particular R = H , Me(1) carbonyl grouping was examined for the following reasons. (1) Previous investigations have focused on the interaction between equivalent lone-pairs ; the series (1) serves as a useful prototype for the study of hetero-

Stereochemical and electronic interaction studies of 4′-substituted 2-(phenylselanyl)-2-(ethylsulfinyl)-acetophenones

“…conjugation and the LPO1→σ*C2C3 and LPO1→σ*C2C25 through bond coupling interactions [34]. For all the conformers in the whole series, the latter interactions are almost constant (ca.…”

“…and LPO1→σ*C2C25 through bond coupling interactions [34]. The former, like in the CRSR/CSSS compounds, was found to be slightly stronger for the 4'-electron-donating derivative 4b.…”

Spectroscopic and theoretical studies of some 2-substituted N-methoxy-N-methyl-amides

“…p à CO orbital interaction value for the gauche (g 1 and g 2 ) conformers may be attributed to the close contact Y dÀ (4)ÁÁÁN dÀ (7) (see Tables 3 and 4). This originate a repulsive electrostatic interaction between the Y dÀ (4)ÁÁÁN dÀ (7) atoms along with four electrons repulsion (Yp2p N ) (through-space interaction) [22], which act decreasing the n N lone pair ionization energy of the gauche conformers relative to the cis one by ca. 6 kcal mol À1 (Table 7).…”

Interaction entre le groupe carbonyle et les hétéroatomes des acétates d'éthyle α-substitués

“…Enfin, l'interaction dipolaire sera faible dans la forme IV, mais ce conformkre prCsente la particularit6 d'autoriser un effet transannulaire (29) (fig. 6), dCja envisagC pour les a-morpholino et pipCridinoacCtophCnone (2) et prCvu dans le modkle des interactions orbitalaires spatiales (24). I1 en rCsulte un abaissement de la bande vco correspondante par rapport a celle de I'acCtate d'Cthyle et la polarit6 attendue doit etre supCrieure ti celle de I1 ou 111.…”