title: Experimental and theoretical study of hydrogen atom abstraction from n-butane by lanthanum oxide cluster anions.
abstract: Lanthanum oxide cluster anions are prepared by laser ablation and reacted with n-C(4)H(10) in a fast flow reactor. A time-of-flight mass spectrometer is used to detect the cluster distribution before and after the reactions. (La(2)O(3))(m=1-3)OH(-) and La(3)O(7)H(-) are observed as products, which suggests the occurrence of hydrogen atom abstraction reactions: (La(2)O(3))(m=1-3)O(-) + n-C(4)H(10) → (La(2)O(3))(m=1-3)OH(-) + C(4)H(9) and La(3)O(7)(-) + n-C(4)H(10) → La(3)O(7)H(-) + C(4)H(9). Density functional theory (DFT) calculations are performed to study the structures and bonding properties of La(2)O(4)(-), La(3)O(7)(-), and La(4)O(7)(-) clusters. The calculated results show that each of La(2)O(4)(-) and La(4)O(7)(-) contains one oxygen-centered radical (O(-•)) which is responsible for the high reactivity toward n-C(4)H(10). La(3)O(7)(-) contains one oxygen-centered radical (O(-•)) and one superoxide unit (O(2)(-•)), and the O(-•) is responsible for its high reactivity toward n-C(4)H(10). The O(-•) and O(2)(-•) can be considered to be generated by the adsorption of an O(2) molecule onto the singlet La(3)O(5)(-) with electron transfer from a terminally bonded oxygen ion (O(2-)) to the O(2). This may help us understand the mechanism of the formation of O(-•) and O(2)(-•) radicals in lanthanum oxide systems. The reaction mechanisms of La(2)O(4)(-) + n-C(4)H(10) and La(3)O(7)(-) + n-C(4)H(10) are also studied by the DFT calculations, and the calculated results are in good agreement with the experimental observations.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xu
authors.forename: Yan-Xia
authors.initials: YX
authors.lastname: Zhao
authors.forename: Xiao-Na
authors.initials: XN
authors.lastname: Li
authors.forename: Xun-Lei
authors.initials: XL
authors.lastname: Ding
authors.forename: Sheng-Gui
authors.initials: SG
authors.lastname: He
mesh_terms: D000838:Anions / Q000737:chemistry; D002073:Butanes / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D007834:Lasers; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D000838:Anions; D002073:Butanes; D010087:Oxides; C103829:lanthanum oxide; D007811:Lanthanum; C046888:butane; D006859:Hydrogen