B (C₆F₅) ₃ And IrH (POCOP) Complex Catalyzed DFT Study Of The Hydrosilylation Reaction

At present,with the rapid development of science and technology,theoretical calculation methods are widely used in various fields such as physics,chemistry,and biology.Among them,quantum computational methods are used to study the reaction mechanism of organic chemistry.In this paper,density functional theory is used to study the mechanisms of hydrosilylation of pyridines catalyzed by tri(pentafluorophenyl)borane and the mechanisms of hydrosilylation of CO2 catalyzed by transition metal iridium complexe.The main contents are as follows:Chapter 1 introduces the Lewis acid-base pairs(FLPs)catalytic reactions,and the mechanism of hydrosilylation catalyzed by Lewis acid and transition metal.Chapter 2 introduces the calculation method of theoretical research-density functional theory(DFT).Chapter 3 explores the mechanism of B(C6Fs)3 catalyzed hydrosilylation of pyridines.At the level of M06-2X//B3LYP functional theory,we calculated the reaction pathway.The total reaction is divided into three steps:(1)B(C6Fs)3 catalyzes 2-methylpyridine,3-methylpyridine to generate 1,4-dihydropyridine compounds,and 4-methylpyridine to yield 1,2-dihydropyridine compound;(2)B(C6F5)3 catalyzes the selective formation of 5-silyl pyridine compounds from dihydropyridine compounds;(3)Under the catalysis of B(C6Fs)3,2-methyl-5-silyl pyridines was reduced to generate 5-silylpiperidine,and the 3-methyldihydropyridine compound was reduced with disiloxane(Me2HSi)2O to generate O-bridged bicyclic aza compound.Chapter 4 explores the hydrosilylation mechanism of[IrH(POCOP)]+ complex catalyzing the reduction of CO2 to CH4.At the level of B3LYP functional theory,we calculated the reaction pathways.The reaction is divided into four stages:(1)[IrH(POCOP)]+ complex catalyzes the reduction of carbon dioxide to silylformate.(2)The[IrH(POCOP)]+ complex catalyzes the reduction of the silylformate to bis(silyl)acetal.(3)The[IrH(POCOP)]+ complex catalyzes the reduction of the bis(silyl)acetal to methoxysilane.(4)The[IrH(POCOP)]+ complex catalyzes the reduction of the methoxysilane to the methane.The first reduction process is the rate-determing step in the overall conversion,with a free energy barrier of 29.5 kcal/mol.And the energy barriers of the subsequent three reduction processes are relatively low,which are 12.2 kcal/mol,16.4 kcal/mol,and 22.9 kcal/mol,respectively.Moreover,the in situ generation iridium dihydride[IrH2(POCOP)]are effective in promoting the silylation of carbon dioxide.