Synthesis And Properties Of Aaryl-Substituted Diazaboroles And Organosilicon Heterocycles

In this dissertation, pentaaryl-substituted diazaboroles have been prepared for thefirst time. The structure and luminescence properties of these compounds were alsoinvestigated. In addition, the reactions of Aryl-Substituted silicon compounds wereinvestigated. The new compounds in this dissertation have been fully characterizedand details are as following:1. Seven pentaaryl-substituted diazaboroles:（CPhNAr）₂BPh （Ar=2,6-iPr₂C₆H₃）（1）,（CNpNAr）₂BPh （2）,（CAr’NAr）₂BPh （Ar’=4-CF₃C₆H₄）（3）,（CphNMes）₂BPh （4）,（CPhNPh）2BPh （5）,（CPhNAr）₂BMes （6）, p-[（CAr’NAr）₂B]2（C6H4）（7） have beenprepared for the first time by a novel strategy based on the C C double bondformation from imidoylstannane reagents in the presence of dibromophenylboranes.All the new diazaboroles are luminescent both in solution and in the solid state.The quantum yields （ΦF） of these compounds are apparently affected by the sterichindrance of the aryl group on the boron and nitrogen atoms. The quantum yieldsdecrease with the decrease of the steric hindrance around the boron atom. Theabsorption and fluorescence properties were investigated in tetrahydrofuran,n-hexane and dichloromethane. The results indicated that the absorption andfluorescence properties of these compounds were only slightly affected by solventpolarity. The absorption and emission maxima of1-7red shift apparently incomparison to that of4,5-dihydro derivative8. The quantum yields in the solidstate appear to be related to the4,5-substituents of the central ring. Low quantumyields have been observed for1（0.04）,4（0.03）,5（0.03）, and6（0.04）, featuringthe same C6H5groups in the4,5-positions. In contrast,2, featuring4,5-naphthylgroups, has the enhanced emission （0.40） compared to that in solution. A relativelyhigh ΦF （0.15） is also observed for3. Preliminary DFT calculations wereperformed on1-3which indicated the significant contribution of the4,5-aryl ringsto the LUMOs of1-3.2. Aryl-Substituted silanes have been synthesized: L¹SiCl₂H （L1=2,4,6-Me₃C₆H₂）,L₂SiCl₂H （L2=2,6-iPr₂C₆H₃）, L₃SiCl₂H （L3=2,6-（2,4,6-Me₃C₆H₂）2-C₆H₃）,L₄SiCl₃（L4=2,6-（3,5-Me₂C₆H₃）₂-C₆H₃）. The reaction of L¹SiCl₂H with0.6equivalents N-heterocyclic carbene gave a silicon trimer [L1SiCl2SiH （L1） SiCl2L1]（9）. The silicon dimer [L2SiCl2SiH（Cl）L2]（10） was obtained by the reaction ofL₂SiCl₂H with0.5equivalents N-heterocyclic carbene. The reaction of L₃SiCl₂Hwith equivalent amounts TMSCH（N2）Li yielded a silicon dimer[{L³Si[C（N₂）TMS]}₂（CN₂）]（11）. Reduction of L₄SiCl₃with4equivalents lithiumgenerated the intramolecular C-H activation product silicon hydrogen lithium salt [L⁴SiHLi]（12）. The reaction of compound12with iPr₂PCl generated the simplereplacement product [L⁴Si（H）PiPr₂]（13）.[L⁴SiHCl]（14） was obtained by thereaction of compound13with1equivalent iPr₂PCl. Treatment of12withpivaloylchloride resulted in the replacement product15. Reaction of12with1,1-Br₂-2,5-TMS₂-3,4-Ph₂-silole resulted in the replacement product16. Treatmentof16with1equivalent N-heterocyclic carbene afforded silacyclopentadienylidene[（MeCNiPr）₂C]（TMS₂Ph₂C₄）Si （17）.