Metallic Compounds Of Iron, Cobalt And Ruthenium In The Reaction Mechanism

This dissertation focuses on the mechanistic study of the alkyne insertion of ion complexes, the alkyne insertion of Coblate complexes and the model reaction of CpRu(PH3)2SH and HNCS. The contents are as follows:Firstly, the possible pathway that the reaction of Fe2(CO)8 with alkyne is proposed. Our calculated rusults confirm that the rate determing step is the first step the carbonation of one atom of alkyne, in order to study the nature of carbonation of alkyne, we use substitutes(-CH3,-NH2,-OCH3,-CN) respectively. We suppose two mechanisms, but our calculated results confirm that regardless of whether they are electron-donating or electron-withdrawing, all the substitutes studied here (-CH3,-NH2,-OCH3,-CN)are able to stabilize the TS and intermediate.Secondly, the reaction mechanisms of the model reaction of CpCo(CO)2 (Cp cyclopentadienyl anion) with HC=CH are explored with the aid of the density functional theory, and especially the regioselectivity involved for acetylene insertion into Co-C bond. Analysis of the reaction involved in the related compounds of the structure and bonding characteristics. It is concluded that the insertion of acetylene into the Co-CO bond is more favorable kinetically than that into the Co-C(non-carbonyl atom) bond. The reduced steric hindrance,πconjugated system, as well as the generation of chelate rings exist, reaction thermodynamics are favorable to the cause of the important reasons.Lastly, the reaction mechanisms of CpRu(PPh3)2SH and RNCS(R= Ph,1-Naphth) are investigated by using the model reaction of CpRu(PH3)2SH and HNCS, with the aid of density functional theory calculaitons. Two possible mechanisms are proposed. Based on calculated results by B3LYP, a plausible prediction is given that the second mechanism is more favorable. From their potential energy curves for the two possible mechanisms, one can see the rate-determining step for the reaction is the hydrogen migration process. The overall reaction activation energy for the first mechanism is markedly higher than that for the second mechanism. Therefore, we theoretically predict that this reaction tends to experience hydrogen migraton prior to the dissocation of the PH3 from the metal center. In the second mechanism, the product is finally obtained due to entropy increase, although the product is thermally less stable than the intemediate directly connecting to the product.