Understanding the CO capture reaction through electronic structure analysis of four-membered-ring group-13/N- and B/group-15-based Lewis acid-base pairs.

Incomplete combustion yields a significant byproduct, known for its high toxicity to humans: gas phase carbon monoxide (CO). This study utilized several advanced theoretical methods to examine the factors contributing to the activation energy involved in CO capture by a frustrated Lewis pair (FLP) and to forecast the potential success of the CO capture reaction. The current theoretical findings indicate that among the four-membered-ring Group-13/N-FLP and B/Group-15-FLP molecules, only the B/N-based FLP-type molecule effectively captures CO, considering both thermodynamics and kinetics.

Mechanistic insights into the insertion and addition reactions of group 13 analogues of the six-membered N-heterocyclic carbenes: interplay of electrophilicity, basicity, and aromaticity governing the reactivity.

Three fundamental concepts (aromaticity/basicity/electrophilicity), being heavily used in modern chemistry, have been applied in this work to study the chemical reactivity of six-membered-ring group 13 N-heterocyclic carbenes (G13-6-Rea; G13 = group 13 elements) using density functional theory (BP86-D3(BJ)/def2-TZVP). G13-6-Rea is isolobal to benzene. Two model reactions have been used in the present study: the insertion reaction of G13-6-Rea with methane and the [1 + 2] cycloaddition reaction of G13-6-Rea with ethene.

A computational study to determine whether substituents make E[triple bond, length as m-dash]nitrogen (E = B, Al, Ga, In, and Tl) triple bonds synthetically accessible.

This study theoretically determines the effect of substituents on the stability of the triple-bonded L-E[triple bond, length as m-dash]N-L (E = B, Al, Ga, In, and Tl) compound using the M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp levels of theory. Five small substituents (F, OH, H, CH and SiH) and four large substituents (SiMe(SiBu), SiPrDis, Tbt ([double bond, length as m-dash] CH-2,4,6-{CH(SiMe)}) and Ar* ([double bond, length as m-dash]CH-2,6-(CH-2,4,6-i-Pr))) are used. Unlike other triply bonded L-E[triple bond, length as m-dash]P-L, L-E[triple bond, length as m-dash]As-L, L-E[triple bond, length as m-dash]Sb-L and L-E[triple bond, length as m-dash]Bi-L molecules that have been studied, the theoretical findings for this study show that both small (but electropositive) ligands and bulky substituents can effectively stabilize the central E[triple bond, length as m-dash]N triple bond.

The mechanistic investigations of photochemical decarbonylations and oxidative addition reactions for M(CO) (M = Fe, Ru, Os) complexes.

The mechanisms for the photochemical CO-dissociation and the oxidative addition reactions are studied theoretically using three model systems: M(CO) (M = Fe, Ru, and Os) and the CASSCF/Def2-SVP (fourteen-electron/ten-orbital active space) and MP2-CAS/Def2-SVP//CASSCF/Def2-SVP methods. The structures of the intersystem crossings and the conical intersections, which play a decisive role in these CO photo-extrusion reactions, are determined. The intermediates and the transition structures in either the singlet or triplet states are also computed, in order to explain the reaction routes.

A model study on the photodecarbonyl reaction of (η-CH)M(CO) (M = Co, Rh, Ir).

The group 9 organometallic complexes η-CpM(CO) (M = Co, Rh, and Ir) and Si(CH)(H) have been considered as a model system to study their photochemical decarbonyl reactions as well as the Si-H bond activation reactions using the CASSCF and MP2-CAS computational methods. For the cobalt complex, three kinds of reaction pathways, which result in the same oxidative addition product, are investigated. Our theoretical finding demonstrated that after the photoirradiation, η-CpCo(CO) loses one CO ligand without any difficulty to form either the triplet ([η-CpCo(CO)]) or singlet ([η-CpCo(CO)]) species.

The mechanistic investigations of photochemical carbonyl elimination and oxidative addition reactions of (η-CH)M(CO), (M = Mn and Re) complexes.

We used computational methods to explore the mechanisms of the photochemical decarbonylation and the Si-H bond activation reaction of the group 7 organometallic compounds, η-CpM(CO) (M = Mn and Re). The energies of both conical intersections and the intersystem crossings, which play a decisive role in these photo-activation reactions, are determined. Both intermediates and transition states in either the singlet or triplet states are also computed to furnish a mechanistic interpretation of the whole reaction paths.

Photochemical isomerization reactions of acrylonitrile. A mechanistic study.

The mechanisms for the photochemical isomerization reactions are determined theoretically using the acrylonitrile model molecule. The CASSCF (twelve-electron/eleven-orbital active space) and MP2-CAS methods are respectively used with the 6-311G(d,p) and 6-311++G(3df,3pd) basis sets. The structure of the conical intersection that plays a prominent role in the photoisomerization of acrylonitrile is obtained.