Periodic trends in gas‐phase oxidation and hydrogenation reactions of lanthanides and 5d transition metal cations

Activation of CO2 by Actinide Cations (Th+, U+, Pu+, and Am+) as Studied by Guided Ion Beam and Triple Quadrupole Mass Spectrometry

“…Comparison to the lanthanide series reactivity is also useful. Notably, because 4f electrons do not participate substantially in bonding, the lanthanide oxide cation BDE has been correlated to the promotion energy from the ground state to the first state with a 5d 2 or 5d6s configuration ,, or to the Ln 2+ (5d 1 ) + O – asymptote . Ground and the first excited state with two 5d electrons are listed in Table S3.…”

“…Notably, because 4f electrons do not participate substantially in bonding, the lanthanide oxide cation BDE has been correlated to the promotion energy from the ground state to the first state with a 5d 2 or 5d6s configuration 1,71,73 or to the Ln 2+ (5d 1 ) + O − asymptote. 31 Ground and the first excited state with two 5d electrons are listed in Table S3. Recently, several GIBMS experimental results have been published for reaction 1 with lanthanide cations.…”

“…The lanthanides (Ln), which are An f-block congeners and frequent An proxies, exhibit similar behavior to oxide bonding correlating to the E p (5d 2 ) of each Ln + . Recently, Armentrout has shown that the LnO + BDEs correlate even better (and have a slope of unity) with the Ln 2+ + O – asymptote and promotion to E p (Ln 2+ ,5d 1 ), although this again indicates the same triple bond in LnO + as the correlation with E p (Ln + ,5d 2 ) for the Ln + + O asymptote. Armentrout and co-workers − have begun to systematically study Ln + reactions with carbon dioxide.…”

Gas-Phase Reactivity of Ozone with Lanthanide Ions (Sm+, Nd+) and Their Higher Oxides

“…Although the lanthanide metals are not of atmospheric relevance, they are nonetheless chemically intriguing (see, for instance, the extensive work on lanthanide cation thermochemistry by Armentrout and co-workers). − Atomic lanthanide cations (Ln + ) form very strong oxide bonds, with six valence electrons forming a triple bond between the 5d orbitals on the metal and the 2p orbitals on the oxygen atom. This requires two valence electrons from the lanthanide atom, and the LnO + BDE is strongly correlated to the energy (if any) required to promote f electrons to the bonding d orbitals (an even stronger correlation is seen with the energy required to promote a single f electron to a 5d orbital while transferring a second electron to the oxygen atom, i.e., forming a state correlating to Ln 2+ (5d) + O – ). , This leads to a pronounced trend in BDEs across the periodic table, decreasing steadily from LaO + (∼9 eV) through the half-filled f shell of EuO + (∼4 eV), and then increasing at GdO + before steadily decreasing again as the f shell orbitals become doubly occupied. Bonding in neutral lanthanide oxides is entirely similar, with Ln–O BDEs differing little from the Ln + –O BDEs.…”

“…The energy required to promote f electrons to d orbitals becomes prohibitive. Instead, the two oxygen atoms must share the 5d orbitals, resulting in an average bond order of 1.5 instead of 3 and an OLn + –O BDE of about half that of Ln + –O . The situation should become increasingly dire for LnO 3 + or higher, with covalent bonding diluted among the oxygen atoms.…”