Nitrogen dioxide reactions with atomic lanthanide cations and their monoxides: gas-phase kinetics at room temperature

Abstract

Results of experimental investigations are reported for the gas-phase kinetics of chemical reactions between nitrogen dioxide (NO(2)) and 14 different atomic cations of the lanthanide series, Ln(+) (Ln = La-Lu, excluding Pm), and their monoxides, LnO(+). Measurements were taken with an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer in helium buffer-gas at a pressure of 0.35 +/- 0.01 Torr and at 295 +/- 2 K. The atomic lanthanide cations were produced at ca. 5500 K in an ICP source and allowed to decay radiatively and to thermalize by collisions with Ar and He atoms prior to reaction with NO(2). The atomic ions were observed to react rapidly with NO(2) with large rate coefficients, k > 2 x 10(-10) cm(3) molecule(-1) s(-1), and almost exclusively by oxygen-atom abstraction to produce lanthanide-oxide LnO(+) cations. In contrast to results of previous studies with many other molecules, the reaction efficiency exhibits essentially no dependence upon the energy required to promote an electron to achieve a d(1)s(1) excited electronic configuration, in which two non-f electrons are available to Ln(+) for chemical bonding. Apparently the radical character of NO(2) (X (2)A(1)) leads to the efficient formation of LnO(+) by the end-on abstraction of an oxygen atom by Ln(+). In the reactions with La(+), Ce(+), Pr(+) and Gd(+) an additional minor channel (less than 2%) leads to the formation of NO(+). The LnO(+) product ions participate in various secondary and higher order reactions with NO(2) resulting in the formation of ions of the type LnO(x)(NO)(y)(NO(2))(z)(+) with x = 1-2, y = 0-2, and z = 0-2, as well as the ions NO(+) and NO(2)(+).

Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium

“…[16,17] It was found that neither CeO + nor PrO + react with O 2 or H 2 Ot oy ield the dioxide cations, [16,17] whereas both react with NO 2 to yield CeO 2 + and PrO 2 + according to reaction (2) where M = Ce or Pr. [18] MO…”

Comment on “Role of (NO)2 Dimer in Reactions of Fe+ with NO and NO2 Studied by ICP-SIFT Mass Spectrometry”

“…We have been unable to find data on the reactions with ScO + or ZrO + , while the Bohme group's 2010 paper on NO 2 reactions of atomic lanthanide cations 12 lists the products of LaO + with NO 2 as LaO 2 + and LaO(NO 2 ) + , not NO + , in contradiction with the claim that LaO + produces NO + .…”

Binding of cerium monoxide to annulenes and buckybowls

“…57 The cationic LnO + species are easily formed in the gas phase reactions of bare Ln + cations with oxygen-donor atom molecules. 58 Generally, the lanthanide monoxides cannot be obtained at normal pressure but it is possible to achieve the synthesis under high pressure (from La to Sm) and to keep them in normal conditions in a metastable state. In the case of cerium monoxide the synthesis has to be made under moderate pressures only using as the starting oxide CeO 2 , slightly reduced by heating in forming gas.…”