Gas-phase reactivity of lanthanide and actinide cations with the archetypal organometallic complexes Fe(CO)(5) and Fe(C5H5)(2)

The gas-phase reactions of lanthanide (Ln(+) = La+ - Lu+, except Pm+) and a ctinide (An(+) = Th+, U+) cations with iron pentacarbonyl, Fe(CO)(5), and w ith ferrocene, Fe(C5H5)(2), were studied by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS). In the case of Fe(CO)(5), the obs erved primary products were of the type MFe(CO)(x)(+) (M = La, Ce, Pr, Nd, Gd, Tb: x = 3. M = Ho, Er, Lu: x = 3 and 4: M = Sm, Eu. Dy, Tm, Yb: x = 4. M = Th. U: x = 2 and 3) and evidence was obtained for the presence of direc t Ln-Fe and An-Fe bonds in these species. With Fe(C5H5)(2) the An(+) cation s and the majority of the Ln(+) cations reacted by metal exchange, yielding Ln and An biscyclopentadienyl ions M(C5H5)(2)(+), while the less reactive Ln(+) cations formed the 'adduct' ions LnFe(C5H5)(2)(+). The product ion di stributions observed with the two organometallic reagents and the reaction efficiencies obtained in kinetics studies both revealed a close relation wi th the relative stability of the accessible formal oxidation states of the metal cations. A few thermochemical estimates pertaining to the different s pecies formed in the reactions could also be made. Reactivity studies of Ln . Th and U oxide and hydroxide cations with the iron complexes are also rep orted. (C) 2001 Elsevier Science BN. All rights reserved.