Synthesis And Catalytic Application Of Air-stable Organobismuth/Organoantimony Complexes

The bismuth-or antimony-containing compounds have been widely applied inorganic synthesis and material science because bismuth and antimony resources arevery rich and relatively cheap. Especially, as a consequence of their interesting andunique structural features, plenty of organobismuth/organoantimony compounds arecurrently being extensively studied. Because of the weakness of the M–C （M=Bi, Sb）bond many organobismuth/organoantimony compounds are unstable. Moreover, thesecompounds as Lewis acids are limited due to the weak acid strength and low catalyticactivity. How to design and synthesize high catalytic activity, stable organobismuth/organoantimony compounds and to expand their catalytic applications is the key issuein mordern organometallic Lewis acid chemistry, which will find important scientificsignificance and potential applications.Based on the special features of organobismuth and organoantimony complexes, aseries of binuclear organobismuth/organoantimony complexes via nitrogen bridgedpincer ligand were synthesized. By adopting ferrocene and1,2-diaminocyclohexane,chiral multidentate ligand precursors were synthesized. The component, structure andphysicochemical properties of the compounds were characterized by single crystalX-ray diffraction, nuclear magnetic resonance （NMR）, elemental analysis, thermo-gravimetric analysis （TG-DSC） etc. Their applications in catalysis such ascycloaddition reactions between epoxides and CO2were investigated. Some mainresearch results were obtained as follows:（1） Binuclear organobismuth complexes7a-7c RN（C₆H₄CH₂）₂BiS(R=t-Bu（7a）,c-C₆H₁₁1（7b）, Ph（7c）) bridged by sulfur atom were synthesized by the reactions of5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine chlorides1a-1c RN（C₆H₄CH₂）₂BiCl(R=t-Bu（1a）, c-C₆H₁₁1（1b）, Ph（1c）) with sodium sulfide and their applications wereinvestigated. The results showed that the complexes7a-7c were air-stable, and themetallic centers were fully exposed. The catalysts showed bimetallic cooperativecatalytic activity in cycloaddition reaction between epoxides and CO2. By adoptingco-catalyst Bu4NI, more epoxides could proceed in high selectivity and yields.（2） Binuclear organoantimony complexes10a-10c RN（C₆H₄CH₂）₂SbO(R=t-Bu（10a）, c-C₆H₁₁1（10b）, Ph（10c）) bridged by oxygen atom were synthesized by thereactions of5,6,7,12-tetrahydrodibenz[c,f][1,5]azaantimocine chlorides8a-8c RN（C₆H₄CH₂）₂SbCl(R=t-Bu（8a）, c-C₆H₁₁1（8b）, Ph（8c）) with sodium hydroxide andtheir catalytic applications were investigated. The results show that the complexes10a-10c had certain Lewis acidity and good thermal stability. The catalysts showedbimetallic cooperative catalytic activity in cycloaddition reaction between epoxidesand CO2compared with the complex9c-C₆H₁₁1N（C₆H₄CH₂）₂SbOMe.（3） Ligand precursors17{[Cp₂FeCH（CH₃）][（2-BrC₆H₄CH₂）]}S and21{[（Me3Si）Cp₂FeCH（CH₃）]（2-BrC₆H₄CH₂）} S bridged sulfur atom were synthesized inhigh yields using S-（-）-N,N-dimethyl-1-ferrocenylethylamine （Ugi’s amine）15aCp₂FeCH（NMe₂）CH₃as starting materials through the optimization of reactionconditions, the ligands contained planar chirality and central chirality. Also, new chiralligands23a and23b1,2-C₆H₁₁0（N（2-BrC₆H₄CH₂）₂）₂were synthesized in high yieldsusing1,2-diaminocyclohexane generated by chiral resolution with tartaric acid asstarting materials.