The study of the reactions of transition metal atoms with water is continued in this work. Here we report the study of the reactions of Fe with H2O and FeO with H2. In agreement with previous thermal atom experiments, laser-ablated Fe atoms reacted with H2O to form the FeOH2 and HFeOH molecules as characterized by matrix isolation FTIR spectroscopy. On photolysis, the Fe atoms could further insert into the OH bonds in H2O molecules with a stepwise pattern to form multi metal−oxo core species including HFeOFeH, HFeOFeOH, and possibly HFeOFeOFeH, which were identified by isotopic substitutions and density functional calculations. Reactions of FeO with H2 also lead to HFeOH as the primary product. In addition, a potential energy surface for the Fe + H2O ⇔ FeO + H2 reaction was constructed to elucidate the reaction mechanisms.

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 good accord with experimental results. We show that the stereochemical control observed in radical halogenation reactions can be explained without the use of Skell hypothesis. The trends of the calculated energy differences between the gauche and trans transition states of reactions R1 and R2, the rotational barriers of XCH2CH2 • radicals, and the gauche effect of XCH2CH3 can be rationalized in a uniform manner in terms of hyperconjugation interaction.