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    題名: Theoretical Study of the Reaction Mechanism of BO, B2O2, and BS with H2
    作者: Chin, Chih-hao;Mebel, Alexander M.;黃德彥;Hwang, Der-yan
    貢獻者: 淡江大學化學學系
    日期: 2004-01-22
    上傳時間: 2009-12-01
    出版者: American Chemical Society (ACS)
    摘要: Potential energy surfaces of various reactions in the BO/H2, B2O2/H2, and BS/H2 systems have been studied at the G2M(MP2)//B3LYP/6-311+G(d,p) level of theory. The BO + H2 reaction is shown to proceed by abstraction of a hydrogen atom by B to produce OBH + H with the barrier and exothermicity of 8.3 and 6.8 kcal/mol, respectively. The reaction can also occur by 1,2-insertion of BO into the H−H bond or by H abstraction by the O atom; however, the barriers for these channels are much higher, 36.4 and 42.7 kcal/mol, respectively. Via a low ∼0.3 kcal/mol barrier, the OBH + H reaction produces the OBH2 radical, which is the most stable compound in the BO/H2 system and lies 15.9, 2.5, and 4.2 kcal/mol below BO + H2, trans-HBOH, and cis-HBOH, respectively. OBH2 can isomerize to trans-HBOH overcoming a barrier of 27.7 kcal/mol and the latter can rearrange to the cis conformer with a barrier of 10.8 kcal/mol. BOH and H can recombine and form cis- or trans-HBOH without barriers. In the B + H2O reaction, the reactants can first form a weakly bound B−H2O complex, which then can eliminate an H atom producing BOH + H or undergo insertion of B into an O−H bond giving trans-HBOH with barriers of 4.7 and 6.2 kcal/mol relative to the initial reactants, respectively, and trans-HBOH can eventually decompose to OBH + H and a minor amount of BO + H2. Singlet OBBO is shown to be much less reactive with respect to H2 than the BO monomer. Alternatively, after two BO recombine to form a triplet OBBO molecule over a moderate 8.3 kcal/mol barrier, t-OBBO can easily react with H2 producing either BO + OBH2 (via a t-OBBH2O intermediate) or OBBOH + H with barriers of 4.4 and 7.4 kcal/mol, respectively. The reactions in the BS/H2 system are shown to be similar to those for BO/H2, except that BS cannot insert into H2, SBH2 resides in a much deeper potential well (37.3 kcal/mol below BS + H2) and can rearrange both to trans- and cis-HBSH, the B−H2S complex is more strongly bound than B−H2O, and the B + H2S reaction is expected to be significantly faster than the reaction of B + H2O.
    關聯: Journal of physical chemistry A 108(3), pp.473-483
    DOI: 10.1021/jp0357471
    顯示於類別:[化學學系暨研究所] 期刊論文


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