Theoretical Studies Of Transition Metal Catalyzed Enyne Compounds Addition Reaction

Transition metal complexes catalyzed addition reaction of unsaturated compounds,especially vinyl and acetylene compunds, play an important role in organic synthesis.They are the key process of pesticide, medicine and fine chemical sythesis. Besides,they are also the research hotspot in catalysis field. Transition metal complexescatalyzed addition reaction of vinyl and acetylene compunds have high atom economy,and low yielding of byproducts. Relative to the substitution reaction, the additionreaction of vinyl and acetylene compunds has higher yield and satisfy the greenchemical concept. The coordinated ligands of transition metal complexes can bechosen appropriately which can make the metal centre have special electronic andspace property. Besides, transition metal complexes catalyzed addition reaction havehigh chemselectivity, enantioselectivity and achieve the selective catalysis. In orderto understand the mechanism of transition metal complex catalyzed addition reactionof vinyl and acetylene compunds and explain the experimental rresults, we carried outa computational study based on density functional theory (DFT). We hope this workpresents a detailed understanding of the catalytic mechanism and provides furtherguide for experimentalists.In the third and the fourth chapter of our dissertation, two experimental reportedtransition metal complexes catalyzed addition reaction of acetylene compunds wereselected as our research object. In order to explore the nature of selective catalysis oftransition metal complexes catalyzed addition reaction of acetylene compunds, wecarried out a computational study based on density functional theory (DFT).Therefore, our work can provide further guide for experimentalists to synthesizefunctional compounds.The main research work in this paper are summerized as follows:Detailed mechanism of the double hydrophosphination of terminal arylacetylenescatalyzed by an iron complex is studied by density functional theory. The calculated results suggest that the reaction proceeds in three steps: active species generation,single hydrophosphination reaction, double hydrophosphination reaction, viz, activespecies regeneration. Besides, it can be concluded that2-Z is the major singlehydrophosphination product, and this result is well in agreement with the observationof the experimental work of M. Kamitani and M. Itazaki. The iron-metal catalyticsystem is only effective for terminal arylacetylenes but not for alkylacetylenes andinternal alkynes. The results uncovered the selectivity of the iron complex for doublehydrophosphination of terminal arylacetylenes. The symmetry of frontier molecularorbitals determines the effectiveness of the catalyst, viz, the reactivity between Int3and alkynes is determined by the symmetry of frontier molecular orbitals. The atomorbital Fe-dxzof Int3and C1-pz, C2-pzof terminal arylacetylenes aresymmetry-adapted, Int3can coordinate with terminal arylacetylenes. However, theatom orbital Fe-dxzof Int3and C1-py, C2-pyof alkylacetylenes and internal alkynesare not efficient symmetry match, therefore, Int3can not coordinate withalkylacetylenes and internal alkynes well. The selective catalysis of the iron complexfor double hydrophosphination of terminal arylacetylenes plays an important role inthe synthesis of functional compounds.Detailed mechanism of the hydroboration reaction of terminal alkynes catalyzed byRu complex is studied by density functional theory. The calculation results suggestthat the hydroboration product with Z configuration is the major intermediate, becausethe rate-determining step`s activation barrier of formation process of Z-vinylboronateis high. The hydroboration reactions catalyzed by Ru complex are chemoselective forterminal alkynes. Terminal alkenes and internal alkynes did not react. In order totestify the necessity of using terminal alkynes as the suitable substrate for Z-selectivehydroboration reaction, we also designed a hypothetical control model utilizing1,2-dimethyl acetylene (CH3C-CCH3) and styrene as the reaction substrates. Thecalculation results suggest that activation barrier of Ru complex catalyzedhydroboration of terminal alkenes and internal alkynes are so high that it can notoccur at room temperature. Therefore, the selective catalysis of the Ru complex forhydroboration reaction of terminal alkynes play an important role in the synthesis of functional compounds.Our research work plays an important role in the synthesis of selective catalyst andprovides further guide for experimentalists to synthesize functional compounds.