Synthesis,transformation And Catalytic Application Of Metal Organic Salts And Complexes Under Mechanical Force

Metal organic salts and complexes are two different types of metal organic hybrid materials.Metalorganic salts are interconnected by intermolecular forces between the metal anion and the organic ligand cation.The complexes are directly linked by coordination bonds formed between the metal and the ligand.Due to their novel and diverse structures and tunable functions,metal organic salts and complexes have a wide range of applications in the fields of magnetic switching,catalysis,metal ion recognition and separation.Mechanochemistry is a green synthesis method that facilitates reactions by mechanical forces and allows efficient reactions in micro-solvent or solvent-free environments.However,mechanochemistry has been less studied in C-S cross-coupling reactions.C-S cross coupling is a reaction using transition metals as catalysts and halogenated hydrocarbons and mercaptans as raw materials.It is of great significance in the fields of organic synthesis,medicine and material chemistry.Therefore,this thesis uses mechanochemical techniques as the main research tool.The preparation of metal compounds and the investigation of their mechanocatalytic properties for C-S cross-coupling reactions were the research objectives of this thesis,mainly in the following aspects.1.Synthesis of 1,3-bis（picolyl）benzimidazolium chloride（L·Cl）in solvent-free conditions using a planetary ball mill;The ligand L·Cl was then ground with the transition metal chloride MCl₂（M=Cu,Zn,Co）to rapidly prepare three pyridine metal-organic salts:2[H₂L]³⁺·3[Cu Cl₄]^2-（1）,[H₂L]³⁺·[Zn Cl₄]^2-·Cl^-（2）,[H₂L]³⁺·[Co Cl₄]^2-·Cl^-（3）and three pyridine complexes:[Cu L（μ-Cl）Cl₂]₂（4）,[Zn（L）Cl₃]（5）,[Co（L）Cl₃]（6）.The foregoing compounds were characterised and analysed using powder X-ray diffraction,single crystal X-ray diffraction and infrared spectroscopy.2.The exploration of the solid state transformation process from metal organic salts to complexes.The results show that when metal organic salts 1-3 are ground with a strong base（potassium tert-butoxide）,the Cl^-in the complexing anion[MCl₄]^2-（M=Cu,Zn,Co）is delocalised by forming HCl with the H⁺of the protonated pyridine group and forming the N-M（M=Cu,Zn,Co）coordination bond of complexes 4-6.3.C-S cross-coupling reactions under mechanical grinding were explored using2-mercaptobenzothiazole and 2-bromoacetophenone as template reactions and the above metal compounds as catalysts.The results show that complex 4 has the best catalytic activity.The best grinding conditions were determined by screening:1.0 mol%of complex 4 was added,60μL of acetonitrile（η=0.16）was added as an auxiliary grinding agent and 99%yield was achieved by grinding for 20 min.Subsequently,the optimum grinding conditions were applied to different substrates,confirming the good functional group compatibility of the system.The work in this article ranges from mechanosynthesis to mechanocatalysis,preparing six new metal organic compounds and applying them to the construction of C-S bonds,with only minimal use of solvents.It is a simple method with simple steps and mild conditions that provides researchers with ideas to continue exploring the application of mechanochemistry to organic reactions.