Bond dissociation energies of low-valent lanthanide hydroxides: lower limits from ion–molecule reactions and comparisons with fluorides. Issue 19 (11th May 2021)

• Record Type: Journal Article
• Authors: Parker, Mariah L.; Jian, Jiwen; Gibson, John K.
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 19(2021)
• Page Start: 11314
• Page End: 11326
• Publication Date: 2021-05-11
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp01362a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Ion–molecule reactions elucidate bond dissociation energies of elementary molecules like YbOH + and YbF + . Observed reactions tentatively suggest similar bonding in lanthanide hydroxides and fluorides, and definitely suggest a need for further inquiry. Abstract : Despite that bond dissociation energies (BDEs) are among the most fundamental and relevant chemical properties they remain poorly characterized for most elementary lanthanide hydroxides and halides. Lanthanide ions Ln + = Eu +, Tm + and Yb + are here shown to react with H2 O to yield hydroxides LnOH + . Under low-energy conditions such reactions must be exothermic, which implies a lower limit of 499 kJ mol −1 for the Ln + –OH BDEs. This limit is significantly higher than previously reported for YbOH + and is unexpectedly similar to the BDE for Yb + –F. To explain this apparent anomaly, it is considered feasible that the inefficient hydrolysis reactions observed here in a quadrupole ion trap mass spectrometer may actually be endothermic. More definitive and broad-based evaluations and comparisons require additional and more reliable BDEs and ionization energies for key lanthanide molecules, and/or energies for ligand-exchange reactions like LnF + OH ↔ LnOH + F. The hydroxide results motivated an assessment of currently available lanthanide monohalide BDEs. Among several intriguing relationships is the distinctively higher BDE for neutral LuF versus cationic LuF +, though quantifying this comparison awaits a more accurate value for the anomalously high ionization energy of LuF.