Synthesis And Reduction Of Anthracene Substituted Boron-containing Compounds

Studies on the structure and properties of free radical compounds are of great significance in understanding the chemical reaction process and mechanism of free radicals,revealing the causes of aging and cancer,and preventing air pollution.However,due to the high activity and short lifetime of free radicals,it is difficult to stabilize and separate them,which affects the exploration of their structure and properties.As an important branch of free radical chemistry of main group elements,organic boron radical chemistry has become one of the new research fields in recent years.However,due to its high activity and short lifetime,it is difficult to stabilize and separate boron radicals.The research and exploration of their structure and reaction are still in the initial stage.Owing to the two difficulties of boron radicals,the structure and properties of anthracene-substituted boron-containing compounds are studied in detail in this paper.It consists of five chapters:In the first chapter,the research status of boron radical chemistry is briefly reviewed.In the second chapter,we had synthesized an anthracene-bridged diboron compound 1 and prepared its radical anion 1^·-and dianion 1^2-by step reduction with alkaline metal potassium.The geometry and electronic structure of the reduction products were studied by cyclic voltammetry,X-ray single crystal diffraction,UV-vis,EPR and DFT calculation.The crystal structures show that the skeleton of the radical anion 1^·-is still planar having a semiquinoidal structure,and the dianion 1^2-has two B-C double bonds which has a puckered quinoidal structure.With the gradual addition of electrons,the aromaticity of the anthracene ring gradually disappeared.In addition,the DFT results are in good agreement with the experimental data.In the third chapter,in view of the excellent performance of the anthracene substituted group in the above work,we continued to synthesize an anthracene substituted monoboron compound 1-H and prepared its dimer potassium complex 2 by reacting with K?NSiMe₃?₂ reagent.Complex 2was reduced by alkali metal potassium,and the reduction product 3 was obtained.The electronic structure and aggregation behavior of reduction product 3 was studied by cyclic voltammetry,X-ray single crystal diffraction,UV-Vis,EPR and DFT calculation.The experimental results show that3 has a K₃O₂B₂ cluster with planar anthracene moieties,and shows triplet diradical character.At the same time,the ligand 1-H was reduced by alkali metal potassium,and the closed-shell compound 4with similar aggregation structure of K₃O₂B₂ was obtained.However,the aromatic structure of anthracene ring was destroyed due to the addition of hydrogen atom,which was the product of hydrogenation product of 3.These aggregation behaviors are mainly caused by cation-?interaction,which plays an important role in the stabilization and formation of the reduction fragments.In the fourth chapter,in view of the high reactivity of boron radicals,we continued to synthesize anthracene-substituted monoboron compound 6 and naphthalene-bridged diboron compound 7.Their dimerization product[6-6]^2-and cyclization product 7^2-were obtained by reduction with alkali metal potassium.Further studies confirmed that the intermolecular dimer reaction was caused by the cyclization of boron radicals.There is a balance between the intramolecular cyclization product7^2-and the radical.The solid state is the intramolecular cyclization product and the solution state is the radical.In the five chapter,we have made a summary for this article.