Density functional calculations have been applied to study and elucidate nickel(0)/N-heterocyclic carbene-catalyzed intramolecular alkene hydroacylation. The calculations showed that nickel(0)-catalyzed intramolecular alkene hydroacylation involved four potential reaction channels (I, II, III, and IV), and pathway IV was predicted to be more favorable than the other three. Two pathways, I and II, had three steps (oxidative addition, hydrogen migration, reductive elimination), and the rate-determining step was hydrogen migration. Pathway III proceeded through oxidative cyclization, β-hydride elimination, and hydrogen migration, and the rate-determining step was β-hydride elimination. Pathway IV included four steps (oxidative cyclization, dimerization, β-hydride elimination, hydrogen migration), and the rate-determining step was again β-hydride elimination. Oxidative cyclization was easy and led to rapid dimerization, greatly reducing the free energy of β-hydride elimination. The binuclear nickelacycle intermediate was observed in Ogoshi’s experiments, and it was identified by nuclear magnetic resonance (NMR). The dominant product was the five-membered benzocyclic ketone p1. All results agreed with Ogoshi’s experiments.

Density functional theory (DFT) was used to study the cobalt(I)-catalyzed enantioselective intramolecular hydroacylation of ketones and alkenes. All intermediates and transition states were fully optimized at the M06/6-31G(d,p) level (LANL2DZ(f) for Co). The results demonstrated that the ketone and alkene present different reactivities in the enantioselective hydroacylation. In ketone hydroacylation catalyzed by the cobalt(I)–(R,R)-Ph-BPE complex, reaction channel “a” to (R)-phthalide was more favorable than channel “b” to (S)-phthalide. Hydrogen migration was both the rate-determining and chirality-limiting step, and this step was endothermic. In alkene hydroacylation catalyzed by the cobalt(I)–(R,R)-BDPP complex, reaction channel “c” leading to the formation of (S)-indanone was the most favorable, both thermodynamically and kinetically. Reductive elimination was the rate-determining step, but the chirality-limiting step was hydrogen migration, which occurred easily. The results also indicated that the alkene hydroacylation leading to (S)-indanone formation was more energetically favorable than the ketone hydroacylation that gave (R)-phthalide, both thermodynamically and kinetically.

Density functional theory (DFT) was used to investigate nickel-catalyzed ring-opening hydroacylation of methylenecyclopropanes and benzaldehydes. The results indicated that the Ni-P(n-Bu)3 complex exhibited much more excellent catalysis than the other two complexes (Ni-PMe3 and Ni-P(t-Bu)3). The hydrogen migration was the rate-determining step, and the β-carbon elimination was the chirality-limiting step. The dominant product was a (S,S)- cis ketone. The phosphine ligand P(n-Bu)3 changed the rate-determining step, and greatly decreased the free energies of the rate-determining step and chirality-limiting step. The use of P(n-Bu)3 generally decreased the free energies of the intermediates and transition states. The possible role of P(n-Bu)3 was the transformation of the electron and geometry structures of those intermediates and transition states.

•We studied the different reactivity of two π bonds of isoprene.•We studied the role of the ligands hydride, carbonyl, chloride, and triphenylphosphine of RuHCl(CO)(PPh3)3.•We studied the effect of the di-ruthenium complexes.Density functional theory (DFT) was used to investigate ruthenium hydride-catalyzed addition reactions of benzaldehydes to isoprenes. Calculation indicated that two π bonds of isoprene had different reactivity, and the less substituted one had better reactivity. The role of the ligands hydride, carbonyl, chloride, and triphenylphosphine of RuHCl(CO)(PPh3)3 were studied in our present work. The hydride was active, and promoted this reaction. The carbonyl or chloride was not used as a carrier of hydrogen migration reaction, so they could not change the reaction channels. The only role of them was the transformation of the electron and geometry structures of those intermediates and transition states. The triphenylphosphine decreased generally the free energies of the intermediates and transition states. The di-ruthenium complexes were not an efficient catalyst.Calculation indicated that two π bonds of isoprene had different reactivity, and the less substituted one had better reactivity. The role of the ligands hydride, carbonyl, chloride, and triphenylphosphine of RuHCl(CO)(PPh3)3 were studied in our present work.

Density functional theory (DFT) was used to investigate cobalt(0)-catalyzed intramolecular hydroacylation of 4-pentenal. The calculated results indicated the involvement of five possible reaction pathways: the formation of cyclopentanone, cyclobutanone, butylenes, cyclobutane, and cyclopropane, respectively. The former two are pathways of Co(0)-catalyzed intramolecular hydroacylation, while the latter three are pathways of decarbonylation. The formation of cyclopentanone was the most favorable channel, and the oxidative addition reaction of 4-pentenal was the rate-determining step. Hence, the dominant product predicted theoretically was cyclopentanone, which was consistent with experimental results. Solvation had a significant effect, and greatly decreased the free energies of all intermediates and transition states.

Density functional theory (DFT) was used to investigate the ruthenium hydride-catalyzed regioselective addition reactions of benzaldehyde to isoprene leading to the branched β,γ-unsaturated ketone. All intermediates and the transition states were optimized completely at the B3LYP/6-31 G(d,p) level (LANL2DZ(f) for Ru, LANL2DZ(d) for P and Cl). Calculated results indicated that three catalysts RuHCl(CO)(PMe3)3 (1), RuH2(CO)(PMe3)3 (2), and RuHCl(PMe3)3 (3) exhibited different catalysis, and the first was the most excellent. The most favorable reaction pathway included the coordination of 1 to the less substituted olefin of isoprene, a hydrogen transfer reaction from ruthenium to the carbon atom C1, the complexation of benzaldehyde to ruthenium, the carbonyl addition, and the hydride elimination reaction. The carbonyl addition was the rate-determining step. The dominant product was the branched β,γ-unsaturated ketone. Furthermore, the presence of one toluene molecule lowered the activation free energy of the transition state of the carbonyl addition by hydrogen bonds between the protons of toluene and the chlorine, carbonyl oxygen of the ruthenium complex. On the whole, the solvent effect decreased the free energies of the species.

The alkynylation of nitrones catalyzed by chiral zinc(II)-complexes was studied by means of the density functional theory (DFT). All the intermediates and transition states were optimized completely at B3LYP/6-31G(d,p) level. Calculation results confirm that this alkynylation of nitrones was endothermic and the total absorbed energy was about 14 kJ/mol. The formation of the M5 complexes was the rate-determining step and the chirality-limiting step for this alkynylation. The transition states TS3-re involve a H(8)–O(2)–Zn(6)–C(9)–C(14)–N(13)–O(12) 7-membered ring, and thus the transition states TS3-si involve a Zn(6)–C(9)–C(14)–N(13)–O(12) 5-membered ring. The dominant reaction is the attack of nitrones from the re-surface of M4. The reactivity of anti-nitrones was stronger than that of syn-nitrones for zinc-catalyzed alkynylation of nitrones. The dominant reaction channel was cata → TS1b → M1b → M2 → M3b → TS2b → M4b → TS3b1-anti-re → M5b1-anti-re → Pro-R. The dominant products predicted theoretically were of R-chirality, (2R)-N-hydroxy-N-methylpent-3-yn-2-amine.

Density functional theory has been used to study the geometries, properties and reactivity of the iron(II)–carbene complexes Cp(CO)(L)FeCHR, L = CO, PMe3, R = Me, OMe, ph, CO2Me. Calculation results confirm that the iron–carbene complexes have two types of geometries: the Fe–C(carbene) bonds of the iron–carbene complexes A, D, E, and H (R = Me, CO2Me) show a strong double-bonded character, and thus the Fe–C(carbene) bonds of the complexes B, C, F, and G (R = OMe, ph) show a strong single-bonded character. The Fe–C(carbene) bonds, and the iron and carbon atoms of Fe–C(carbene) bonds are the reactive center for the iron–carbene complexes. The geometry, electronic structure, and frontier orbitals (HOMO and LUMO) are discussed in detail.