Migliorati V, Gibiino A, Lapi A, Busato M, D'Angelo P. On the Coordination Chemistry of the lanthanum(III) Nitrate Salt in EAN/MeOH Mixtures.
Inorg Chem 2021;
60:10674-10685. [PMID:
34236168 PMCID:
PMC8389800 DOI:
10.1021/acs.inorgchem.1c01375]
[Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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A thorough structural
characterization of the La(NO3)3 salt dissolved
into several mixtures of ethyl ammonium
nitrate (EAN) and methanol (MeOH) with EAN molar fraction χEAN ranging from 0 to 1 has been carried out by combining molecular
dynamics (MD) and X-ray absorption spectroscopy (XAS). The XAS and
MD results show that changes take place in the La3+ first
solvation shell when moving from pure MeOH to pure EAN. With increasing
the ionic liquid content of the mixture, the La3+ first-shell
complex progressively loses MeOH molecules to accommodate more and
more nitrate anions. Except in pure EAN, the La3+ ion is
always able to coordinate both MeOH and nitrate anions, with a ratio
between the two ligands that changes continuously in the entire concentration
range. When moving from pure MeOH to pure EAN, the La3+ first solvation shell passes from a 10-fold bicapped square antiprism
geometry where all the nitrate anions act only as monodentate ligands
to a 12-coordinated icosahedral structure in pure EAN where the nitrate
anions bind the La3+ cation both in mono- and bidentate
modes. The La3+ solvation structure formed in the MeOH/EAN
mixtures shows a great adaptability to changes in the composition,
allowing the system to reach the ideal compromise among all of the
different interactions that take place into it.
The structural properties of the La(NO3)3 salt dissolved into EAN/methanol mixtures were
characterized
by molecular dynamics and X-ray absorption spectroscopy. The La3+ solvation shell undergoes significant changes with increasing
the ionic liquid content of the mixture, progressively losing methanol
molecules to accommodate more and more nitrate anions. The La3+ solvation structure shows great adaptability to composition
changes, passing from a 10-fold bicapped square antiprism geometry
in pure methanol to a 12-coordinated icosahedral complex in EAN.
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