Theoretical studies of electronic structure and structural properties of anhydrous alkali metal oxalates: Part II. Electronic structure and bonding properties versus thermal decomposition pathway

• Published in: Journal of thermal analysis and calorimetry 2014, Vol.115 (1), p.841-852
• Main Authors: Kolezynski, A, Malecki, A
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Carbonates; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Measurement Science and Instrumentation; Oxalates; Oxalic acid; Physical Chemistry; Polymer Sciences
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-013-3210-4

The theoretical analysis of electronic structure and bonding properties of anhydrous alkali metal oxalates, based on the results of DFT FP-LAPW calculations, Bader’s QTAIM topological properties of electron density, Cioslowski and Mixon’s topological bond orders [reported in the first part of this paper by Koleżyński (doi: 10.1007/s10973-013-3126-z )] and Brown’s Bond Valence Model calculations, carried out in the light of thermal decomposition pathway characteristic for these compounds are presented. The obtained results shed some additional light on the origins of the complex pathway observed during thermal decomposition process (two stage process, first the formation of respective carbonate and then decomposition to metal oxide and carbon dioxide). For all structures analyzed, strong similarities in electronic structure and bonding properties were found (ionic-covalent bonds in oxalate anion with C–C bond as the weakest one in entire structure and almost purely ionic between oxalate group and alkali metal cations), allowing us to propose the most probable pathway consisting of consecutive steps, leading to carbonate anion formation with simultaneous cationic sublattice relaxations, which results in relative ease of respective metal carbonate formation.