Yu-Wei Pei

Theoretical study on germylenoid H2GeFBeF

The germylenoid H2GeFBeF was studied by using the DFT B3LYP and QCISD methods in gas phase and in benzene, diethylether, tetrahydrofuran, acetone, and dimethyl sulphoxide solvents. Geometry optimization calculations indicated that H2GeFBeF has three equilibrium configurations, in which the p-complex structure is the lowest in energy and is the most stable structure. The solvent effect on the geometries, energies, and isomerization reactions were discussed. For the stablest structure, the infrared spectrum was simulated.

Theoretical study on the insertion reactions of the germylenoid H2GeClMgCl with RH (R = F, OH, NH2)

The insertion reactions of the germylenoid H2GeClMgCl with RH (R = F, OH, NH2) have been studied by using the DFT B3LYP and QCISD methods. The geometries of the stationary points on the potential energy surfaces of the reactions were optimized at the B3LYP/6-311+G(d, p) level of theory. The calculated results indicate that all the mechanisms of the three insertion reactions are identical to each other. The QCISD/6-311++G(d, p)//B3LYP/6-311+G(d, p) calculated potential energy barriers for the three insertion reactions of R = F, OH, and NH2 are 164.62, 193.30, and 200.73 kJ mol−1, and the reaction energies for the three reactions are −57.46, −35.65, and −22.22 kJ mol−1, respectively. Under the same situation, the insertion reactions should occur easily in the following order H-F > H-OH > H-NH2. In THF solvent the insertion reactions get more difficult than in gas phase.

THEORETICAL INVESTIGATION ON THE INSERTION REACTIONS OF THE GERMYLENOID H2GeLiF WITH RH (R = Cl, SH, PH2)

The insertion reactions of the germylenoid H2GeLiF with RH (R = Cl, SH, PH2) were studied for the first time by using the DFT B3LYP and QCISD methods. The geometries of the stationary points on the potential energy surfaces of the reactions were optimized at the B3LYP/6-311+G (d,p) level of theory. The calculated results indicated that the mechanisms of the insertion reactions of H2GeLiF with HCl, H2S, and PH3 are identical to each other. The QCISD/6-311++G(d,p)//B3LYP/6-311+G(d,p) calculated potential energy barriers of the three reactions are 81.80, 123.39 and 205.56 kJ/mol, and the reaction energies for the three reactions are -58.74, -33.51 and -13.35 kJ/mol, respectively. Under the same situation, the insertion reactions should occur easily in the following order H–Cl > H–SH > H–PH2. The insertion reaction in THF solution is easier than in gas phase.

CASPT2 study on low-lying states of HBS+ and HSB+ cations

Some low-lying states of the nine-valence-electron systems HBS+ and HSB+ cations have been studied by large-scale theoretical calculations using three methods CASSCF, CASPT2, and DFT B3LYP with the contracted atomic natural orbital and cc-pVTZ basis sets. The geometries of all stationary points along the potential energy surfaces were optimized and the energies were calculated. The potential energy curves of isomerization reactions between HBS+ and HSB+ were calculated as a function of HBS bond angle. The calculated results indicated that the ground-state HBS+ is linear, while the ground-state HSB+ is bent, which is in contradiction to Walshs rules predicting linear structures for the HXY systems containing 10 or less valency electrons.

THEORETICAL STUDY ON HBeP- AND HPBe- ANIONS USING MULTICONFIGURATION SECOND-ORDER PERTURBATION THEORY

Some low-lying states of the nine-valence-electron systems HBeP- and HPBe- anions have been studied for the first time using three methods CASSCF, CASPT2 and B3LYP with the contracted atomic natural orbital (ANO) and cc-pVTZ basis sets. The geometries of all stationary points along the potential energy surfaces were optimized at the CASSCF/ANO, CASPT2/ANO and B3LYP/cc-pVTZ levels. The potential energy curves of isomerization reactions between HBeP- and HPBe- were calculated as a function of HBeP bond angle. The ground and the first excited states of HBeP- are predicted to be X2Π and A2Σ+ states, respectively. The X2Σ+ and A2Π states of the linear HPBe- are both first-order saddle points because they have unique imaginary frequency. Two bent minima M1 and M2 were found along the 12A′ and 12A″ potential energy surfaces, respectively. The calculated results indicated that the ground-state HBeP- is linear, while the ground-state HPBe- is bent.