Assessing the effects of covalent, dative and halogen bonds on the electronic structure of selenoamides

Here, the interaction between N,N-dimethyl-selenobenzoamide PhC(=Se)NMe2 (1) and various Lewis acids of different strengths, namely IC6F13(I), B(C6F5)(3) (B) and Met, has been analysed by a combined experimental and theoretical approach. In all cases, an increase of the C-NMe2 rotational barrier has been evidenced and quantified by H-1-variable temperature-exchange NMR spectroscopy (VT-EXSY) in the cases of 1-I and 1-B. For B(C6F5)(3), the structure of the adduct has been elucidated by single crystal X-ray diffraction, allowing the lengthening of the Se-C bond (186 pm) and the consequent double characteristic of the C-NMe2 bond (131 pm) to be measured. Computational studies (mainly natural bond orbitals and natural orbital for chemical valence analyses) gave precious insight into the effect of various Lewis acids on the electronic structure of 1. The advantages and the limitations of this new method to characterize chemical interactions are discussed.

Automated summary

In this study, the interaction between N,N-dimethyl-selenobenzoamide and various Lewis acids of different strengths was analyzed using a combined experimental and theoretical approach. The increase of the rotational barrier for the C-NMe2 bond was observed in all cases and quantified using H-1 variable temperature-exchange NMR spectroscopy. The crystal structure of the adduct with B(C6F5)(3) was determined, revealing a lengthened Se-C bond and a double bond characteristic for the C-NMe2 bond. Computational studies provided valuable insights into the effect of different Lewis acids on the electronic structure of the compound. The advantages and limitations of this new method for characterizing chemical interactions were discussed.