Theoretical Studies On Structures,Properties And Reactions Of Several Important Organic Intermediates

This thesis mainly covers two aspects,one is the theoretical studies on the structures,properties,and reactions of several organic silylenoid intermediates.In this part,the addition reactions of H2 Si Li F with ethylene,the addition reactions of HCl Si Li Cl with acetone,the structures of H2 Si Al Cl3 and its addition reactions with ethylene,the addition reactions of H2 Si Sm Br2 with ethylene,and the insertion reactions of H2 Si Al Cl3 with RH(R = F,OH,NH2,Cl,SH,PH2)were investigated.The other is the theoretical studies on the structures,properties,and reactions of several organic germylenoid intermediates.In this part the addition reactions of H2 Ge Li F with ethylene and formaldehyde,the structures of H2 Ge FMg F and its addition reactions with ethylene,the addition reactions of H2 Ge Al Cl3 with ethylene,the structures of H2 Ge Zn Cl2 and its addition reactions with ethylene,the insertion reactions of H2 Ge Li F with halogenated germane Ge H3X(X = F,Cl,Br),the insertion reactions of H2 Ge FMg F with RH(R = F,OH,NH2,Cl,SH,PH2),and the H2 elimination reactions of H2 Ge FMg F with RH(R = Cl,SH,PH2)were studied.1.Theoretical studies on the structures,properties and reactions of several organic silylenoid intermediates1.1 The addition reactions of silylenoid H2 Si Li F with ethylene were investigated using DFT B3 LYP and QCISD methods.The calculated results demonstrated that the addition reactions of H2 Si Li F with ethylene could proceed through two pathways,in which the pathway(path A)including one three-member ring transition state has lower barrier height than the pathway(path B)including one four-member ring transition state.Therefore path A is more favorable than path B at the same conditions.In order to consider the solvent effects,the PCM model and THF solvent were employed.The calculated results indicated that the addition reactions of H2 Si Li F with ethylene could occur easier in solvent than those in vacuum.1.2 The addition reactions of HCl Si Li Cl with acetone were calculated using M06-2X and QCISD methods.The calculated results proved that the possible mechanisms of the reference[21] proposed are rational.The third pathway was found.The solvent effects were studied by using PCM model in n-hexane solvent.The results indicated that the mechanisms of the addition reactions in solvent are similar to those in vacuum.1.3 The structures of H2 Si Al Cl3 and its addition reactions with ethylene were investigated by means of M06-2X and QCISD methods.The calculated results indicated that there are two possible pathways in the addition reactions,and the path just involved one transition state is easier to occur.The solvent effects on the addition reactions were calculated using CH2Cl2 solvent and the results showed that the solvent is unfavorable for the reactions.1.4 The addition reactions of H2 Si Sm Br2 with ethylene were studied by employing M06-2X and QCISD approaches.The results indicated that the path including one three-member ring is easier to occur.The addition reactions are spontaneous when the temperature is below 1300 K.In THF solvent,the path included one three-member ring is still easier to occur.1.5 The insertion reactions of H2 Si Al Cl3 with RH(R = F,OH,NH2,Cl,SH,PH2)were investigated by means of M06-2X and QCISD methods.The results demonstrated that all of the mechanisms of six insertion reactions are similar.The calculations about solvent effect showed that the insertion reactions in CH2Cl2 solvent are more difficult to occur than in vacuum.2.Theoretical studies on the structures,properties and reactions of several organic germylenoid intermediates2.1 The addition reactions of the simplest germylenoid H2 Ge Li F with ethylene were studied using B3 LYP and QCISD methods.The results indicated that there are two possible channels in the addition reactions,in which path A involved a three-member ring transition state,while path B involved a four-member ring transition state.Path A is easier to occur than path B.The The calculations about solvent effect demonstrated that the additions of H2 Ge Li F with ethylene get easier in THF solvent than in vacuum.2.2 The addition reactions of H2 Ge LiF with formaldehyde were investigated by means of M06-2X and QCISD methods.The calculated results revealed that there are two precursor complexes,two transition states,and one intermediate connecting the reactants and products along the potential energy surface.The barrier height of this addition reaction is 58.86 k J/mol in vacuum.The solvent effect on the addition reaction was considered and the results indicated that the THF solvent is favorable for the reaction.2.3 The equilibrium structures of H2 Ge FMg F were studied using B3 LYP and QCISD methods,and the addition reactions of its most stable structure with ethylene were also investigated.The results indicated that there are two possible pathways in the addition reactions,and the path including one three-member ring transition state is easier to occur.The solvent effects were probed on the structures and addition reactions.The calculated results demonstrated that the THF solvent is favorable for the addition reactions of H2 Ge FMg F with ethylene.2.4 The addition reactions of aluminum germylenoid H2GeAlCl3 with ethylene were studied using M06-2X and QCISD methods.The selected reactants are the most two stable configurations of H2 Ge Al Cl3,p-complex structure and three membered ring structure.It turned out that there are two possible channels in the addition reactions both for p-complex structure and for three membered ring structure.For the p-complex structure,channel I and II were found and these two channels could occur competitively.While for the three membered ring structure,channel III and IV were found,and channel III could occur easier than channel IV.The solvent effect on the addition reactions was considered using the PCM model and CH2Cl2 solvent.The calculated results indicated that CH2Cl2 solvent is unfavorable for the channels,except for channel II.2.5 Theoretical investigations on structures of zinc germylenoid H2GeZnCl2 and its addition reactions with ethylene were carried out using M06-2X and QCISD approaches,as well as the solvent effects.The results indicated that H2 Ge Zn Cl2 has two isomers,the deformed tetrahedral configuration(1)and p-complex configuration(2),and 1 is more stable than 2.Due to the high isomerization barriers,two isomers could exist stably.The addition reactions of 1 with ethylene involved two possible pathways(A and B),in which path A is easier to occur.The additions of 2 with ethylene only involved one pathway(C).All of the barrier heights calculated in THF solvent are lower than those in vacuum.2.6 The insertion reactions of H2 Ge LiF with halogenated germane GeH3X(X = F,Cl,Br)were studied by means of B3 LYP and QCISD methods.The calculated results revealed that there are one precursor complex,one transition state,and one intermediate connecting reactants and products along the potential energy surface.The exploration of the insertion mechanism provided a new mode for the synthesis of Ge-Ge bond.2.7 The insertion reactions of H2 Ge FMg F with RH(R = F,OH,NH2,Cl,SH,PH2)and the solvent effects were investigated using B3 LYP and QCISD methods.The calculated results indicated that for each insertion reaction,along the potential energy surface,there are one transition state and one intermediate connecting the corresponding reactants and products.The mechanism of all the insertion reactions is similar,but the degree of difficulty is not the same.For the first row RH,the insertion reactions should occur easily in the following order: H-F > H-OH > H-NH2,while for the second row RH,the order is H-Cl > H-SH > H-PH2.The solvent is favorable for insertion reactions,and with the raising of the solvent polarity,the reaction could occur more and more easily.The reaction order in solvent is same as in vacuum.2.8 The H2 elimination reactions of H2 Ge FMg F with RH(R = Cl,SH,PH2)were calculated in vacuum and four different solvents by using B3 LYP and QCISD methods.The calculated results demonstrated that there is only one transition state connecting respective reactants and products along the potential energy surfaces.The H2 elimination reactions should occur easily in the following order: H-Cl > H-SH > H-PH2.The solvents are favorable for the H2 elimination reactions.