The Syntheses, Structures And Properties Of Functionalized Carborane Deirvatives

Since the1960s, the chemistry of closo-C₂B₁₀H₁₂carborane has witnessed rapiddevelopment. The icosahedral closo-C2B10H12carboranes and their derivatives have attractedconsiderable attention due to their unique molecular skeleton, excellent thermal stability andespecially the potential applications in many fields, including, e.g. biomedical science,optical materials, macromolecules, catalysis, ionic liquids, and ion-selective electrodes.The reactions of o-carboranyllithium with2-pyridinecarboxaldehyde, trimethyl borate,tripropyl borate and boron tribromide, respectively, are described, and the mechanism ofthe reaction system of carboranyllithium/2-bromomalononitrile is studied. The reactionproducts were separated, and their structures and some properties were studied by means ofvarious techniques.There are five sections in this thesis which are as follows:Chapter1presents the current status of the development of the chemistry of carboranes, ageneral review of the reactivities and applications of carborane derivatives is given, as wellas the purposes of this thesis.Chapter2describes the reactions of o-carboranyllithium with2-pyridinecarboxaldehyde,ferrocenecarboxaldehyde, respectively, and the reaction of o-carborane with2-pyridinecarboxaldehyde promoted by tetrabutylammonium fluoride. The reaction ofo-carboranyllithium with2-pyridinecarboxaldehyde gives the two products closo-1-[（C₅H₄N）CHOH]-1,2-C₂B₁₀H₁₁（1）（yield4.6%） and closo-1,2-[（C₅H₄N）CHOH]₂-1,2-C₂B₁₀H₁₀（2）（65.7%）; while o-carborane reacts with2-pyridinecarboxaldehyde in thepresence of tetranbutylammonium fluoride produces compound1in high yield （90.8%）; similarly, o-carboranyllithium reacts with ferrocenecarboxaldehyde under optimi-zed conditions affords closo-1-[C₁₀H₉FeCHOH]-1,2-C₂B₁₀H₁₁（yield49%） and closo-1,2-[C₁₀H₉FeCHOH]₂-1,2-C₂B₁₀H₁₀（27%）, both in higher yields than original reported. Thenew products have been characterized by IR and NMR spectroscopy, massspectrometry and single crystal X-ray diffraction. Compound2exhibits interesting polymorphism （monoclinic2a and triclinic2b）. The photoluminescence of1and2bwas investigated in the solid and solution states at room temperature, respectively.The reactions of o-carboranyllithium with trimethyl borate, tripropyl borate andborontribromide, respectively, are described in chapter3. An intermediate featuring afour-coordinate boron structure may have formed in the reactions ofo-carboranyllithium with trimethyl borate and tripropyl borate. However, after quenchedwith water, the newly formed Ccage-B bonds are destroyed and the starting materialo-carborane is recovered; when the reaction with boron tribromide is quenched by dropsof water, o-carboranyl boronic acid was obtained and characterized by IR and NMRspectroscopy.In chapter4, the mechanism of the reaction of o-carboranyllithium with2-bromomalononitrile is studied. The product, zwitterionic nido-carborane3, has beencharacterized by IR and NMR spectroscopy and mass spectrometry, and the electronicstructure has been studied by computational methods. A series of reactions weredesigned and carried out to explore the mechanism of the reaction.Chapter5summarizes the results of the thesis and a prospect of the carborane isalso made.