Gui-ling Zhang

Substitution effect on the geometry and electronic structure of the ferrocene

The substitution effects on the geometry and the electronic structure of the ferrocene are systematically and comparatively studied using the density functional theory. It is found that NH2 and OH substituents exert different influence on the geometry from CH3, SiH3, PH2, and SH substituents. The topological analysis shows that all the CC bonds in a–g are typical opened‐shell interactions while the FeC bonds are typical closed‐shell interactions. NBO analysis indicates that the cooperated interaction of d → π* and feedback π → d + 4s enhances the Fe‐ligand interaction. The energy partitioning analysis demonstrates that the substituents with the second row elements lead to stronger iron‐ligand interactions than those with the third row elements. The molecular electrostatic potential predicts that the electrophiles are expected to attack preferably the N, O, P, or S atoms in FerNH2, FerOH, FerPH2, and FerSH, and attack the ring C atoms in FerSiH3 and FerCH3. In turn, the nucleophiles are supposed to interact predominantly by attacking the hydrogen atoms. The simulated theoretical excitation spectra show that the maximum absorption peaks are red‐shifted when the substituents going from second row elements to the third row elements.

Theoretical study on the reaction of SiH(CH(3))(3) with SiH(3) radical.

The multiple‐channel reactions SiH3 + SiH(CH3)3 → products are investigated by direct dynamics method. The minimum energy path (MEP) is calculated at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the MC‐QCISD (single‐point) method. The rate constants for individual reaction channels are calculated by the improved canonical variational transition state theory with small‐curvature tunneling correction over the temperature range of 200–2400 K. The theoretical three‐parameter expression k(T) = 2.44 × 10−23T3.94 exp(−4309.55/T) cm3/(molecule s) is given. Our calculations indicate that hydrogen abstraction channel R1 from SiH group is the major channel because of the smaller barrier height among five channels considered.

Theoretical studies on the reactions CH3SCH3 with OH, CF3, and CH3 radicals

The multiple‐channel reactions OH + CH3SCH3 → products, CF3 + CH3SCH3 → products, and CH3 + CH3SCH3 → products are investigated by direct dynamics method. The optimized geometries, frequencies, and minimum energy path are all obtained at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the MC‐QCISD (single‐point) method. The rate constants for eight reaction channels are calculated by the improved canonical variational transition state theory with small‐curvature tunneling contribution over the temperature range 200–3000 K. The total rate constants are in good agreement with the available experimental data and the three‐parameter expressions k1 = 4.73 × 10−16T1.89 exp(−662.45/T), k2 = 1.02 × 10−32T6.04 exp(933.36/T), k3 = 3.98 × 10−35T6.60 exp(660.58/T) (in unit of cm3 molecule−1 s−1) over the temperature range of 200–3000 K are given. Our calculations indicate that hydrogen abstraction channels are the major channels and the others are minor channels over the whole temperature range.

Theoretical study on the OH + CH3NHC(O)OCH3 reaction

The multiple‐channel reactions OH + CH3NHC(O)OCH3 → products are investigated by direct dynamics method. The optimized geometries, frequencies, and minimum energy path are all obtained at the MP2/6‐311+G(d,p) level, and energetic information is further refined by the BMC‐CCSD (single‐point) method. The rate constants for every reaction channels, R1 , R2 , R3 , and R4 , are calculated by canonical variational transition state theory with small‐curvature tunneling correction over the temperature range 200–1000 K. The total rate constants are in good agreement with the available experimental data and the two‐parameter expression k(T) = 3.95 × 10−12 exp(15.41/T) cm3 molecule−1 s−1 over the temperature range 200–1000 K is given. Our calculations indicate that hydrogen abstraction channels R1 and R2 are the major channels due to the smaller barrier height among four channels considered, and the other two channels to yield CH3NC(O)OCH3 + H2O and CH3NHC(O)(OH)OCH3 + H2O are minor channels over the whole temperature range.

Theoretical study and rate constants calculation for the reactions of SiH3 radical with SiH3CH3 and SiH2(CH3)2

The multiple‐channel reactions SiH3 + SiH3CH3 → products and SiH3 + SiH2(CH3)2 → products are investigated by direct dynamics method. The minimum energy path (MEP) is calculated at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the MC‐QCISD method. The rate constants for individual reaction channels are calculated by the improved canonical variational transition state theory (ICVT) with small‐curvature tunneling (SCT) correction over the temperature range of 200–2400 K. The theoretical three‐parameter expression k1(T) = 2.39 × 10−23T4.01exp(−2768.72/T) and k2(T) = 9.67 × 10−27T4.92exp(−2165.15/T) (in unit of cm3 molecule−1 s−1) are given. Our calculations indicate that hydrogen abstraction channel from SiH group is the major channel because of the smaller barrier height among eight channels considered.

Theoretical study on the Br + CH3SCH3 reaction.

The multiple‐channel reactions Br + CH3SCH3 → products are investigated by direct dynamics method. The optimized geometries, frequencies, and minimum energy path are all obtained at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the G3(MP2) (single‐point) theory. The rate constants for every reaction channels, Br + CH3SCH3 → CH3SCH2 + HBr (R1), Br + CH3SCH3 → CH3SBr + CH3 (R2), and Br + CH3SCH3 →CH3S + CH3Br (R3), are calculated by canonical variational transition state theory with small‐curvature tunneling correction over the temperature range 200–3000 K. The total rate constants are in good agreement with the available experimental data, and the two‐parameter expression k(T) = 2.68 × 10−12 exp(−1235.24/T) cm3/(molecule s) over the temperature range 200–3000 K is given. Our calculations indicate that hydrogen abstraction channel is the major channel due to the smallest barrier height among three channels considered, and the other two channels to yield CH3SBr + CH3 and CH3S + CH3Br are minor channels over the whole temperature range.