Capture of CO₂ by novel diiodo‐N,N‐imidazoliumvinylidene: A theoretical quest

Abstract

Capture of CO 2 by diiodo-N,N-imidazoliumvinylidene, with singlet and triplet minima (1 s and 1 t , respectively), is probed at M06-2X/6-311++G ** level of theory. Ground state appears to be triplet 1 t , which exhibits a rather large singlettriplet energy gap (ΔE s-t = +10.30 kcal mol À1 ). Adsorption of CO 2 over 1 t releases À3.70 kcal mol À1 energy and gives the initial CO 2 adduct, with no transition state (TS). Sequentially, the latter goes through a reactant-like TS, which leads to an internal exothermic attack of the carbene carbon to the adsorbed CO 2 and forms 3 t with conversion energy (E con ) of À6.77 kcal mol À1 . Additional calculations involve endothermic capture of CO 2 by the rather unstable 1 s . The immense potential of the natural bond orbital (NBO) and atom in molecule (AIM) data in elucidating a reaction mechanism is unveiled by employing the electron-pushing technique. Results appear consistent with the proposed mechanism.

Capture of CO2by O, S, and Se substituted tripletN‐heterocyclic vinylidenes: a theoretical comparison

“…The distance between oxygen of CO 2 and hydrogen of N–H appears independent of E trp for asymmetric 1 t – 3 t . This is in contrast to our previous articles, wherein the symmetric vinylidene, we observed a direct relationship between the trapping energy and the distance between CO 2 and the carbene as well as the degree of bending of CO 2 15–17,34 . Here, it seems that the size of O, S, Se, and the hydrogen bond formed in the product affects this issue.…”

“…We have compared and contrasted the possibility of complex formation between CO 2 and six NHVs. We have used NBO donor–acceptor interactions with descending second‐order energy E 2 plus the related total E 2 for each step 16 . We have assessed the theoretical capture of CO 2 by N , N ‐dihalo‐imidazoliumvinylidenes.…”

“…We have used NBO donoracceptor interactions with descending second-order energy E 2 plus the related total E 2 for each step. 16 We have assessed the theoretical capture of CO 2 by N,Ndihalo-imidazoliumvinylidenes. Variations of atomic charges on products are qualitatively and quantitatively justified by their resonance forms and the corresponding NBO donor/acceptor interactions.…”

Use of 5,10‐Disubstituted Dibenzoazaborines and Dibenzophosphaborines as Cyclic Supports of Frustrated Lewis Pairs for the Capture of CO2

“…Theoretical studies were added to those experimental results, to better understand the reaction mechanism behind the capture and reduction of CO 2 , as well as proposing a systematic way to improve the existing FLP playing with the intrinsic properties of the atoms involved. [18,22,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] Considering phosphorus as a LB, boron as a LA, and that the distance between both atoms, may be imposed by a ring structure and/or large substituents, it is possible to design FLP systems to capture CO 2 . Among potential intramolecular FLPs, the tricyclic derivatives of 9,10-dihydroanthracene (DHA) with different substituents in positions 9 and 10 should be mentioned (Figure 1).…”

“…In addition, FLPs are being used to activate CO 2 and reduce it to useful chemicals, [5,31–33] like for example methanol, [24,25,34] methane, [35] formates, [17,31] methoxysilane, [36] in a catalytic fashion or not. Theoretical studies were added to those experimental results, to better understand the reaction mechanism behind the capture and reduction of CO 2 , as well as proposing a systematic way to improve the existing FLP playing with the intrinsic properties of the atoms involved [18,22,37–51] …”