Showing papers by "Zhen Hua Li published in 2001"
TL;DR: In this article, a simple formula for extrapolating energies calculated from finite basis sets to the limit of a complete basis set by scaling the basis set extension energies is presented, combining this basis set extrapolation method with the scaling-all-correlation (SAC) energy method.
14 citations
TL;DR: The stereochemistry of radical halogenation of alkyl halides has been studied by ab initio molecular orbital theory in this paper, where the G2(MP2,SVP) theory was used to predict the stereoselectivity of halogenization.
Abstract: The stereochemistry of radical halogenation of alkyl halides has been studied by ab initio molecular orbital theory. Two key elementary reactions, hydrogen abstraction reaction [XCH2CH3 + Y• → XCH2CH2• + HY (R1)] and halogen abstraction reaction [XCH2CH2• + Y2 → XCH2CH2Y + Y• (R2)], as well as rotational barrier of XCH2CH2• radical, with X = H, F, Cl, and Br and Y = F, Cl, and Br, were studied using the G2(MP2,SVP) theory. Reactions R1 and R2 with X = F, Cl, and Br were found to be stereoselective. For X = F, both reactions prefer a gauche abstraction, whereas for X = Cl and Br, both reactions prefer a trans pathway. The high rotational barriers of ClCH2CH2• and BrCH2CH2• radicals and the low abstraction barriers of their reactions with Cl2 and Br2 are the two main factors that guarantee the retention of their radical configuration during the abstraction reactions. Thus, radical chlorination and bromination of alkenes and chlorine- and bromine-substituted alkanes are predicted to be stereospecific, in goo...
11 citations