Influence of pseudo-polymorphism on the structure and thermal behavior of the new barium β-diketonate complexes [Ba(adtfa)2(18-crown-6)] and [Ba(adtfa)2(18-crown-6)](CDCl3)2

The new barium beta-diketonate complexes with 18-crown-6 [Ba(adtfa)(2)(18-crown-6)] (1) and [Ba(adtfa)(2)(18-crown-6)](CDCl3)(2) (2) (adtfa = 1,1,1-trifluoro-4-(1-adamantyl)-2,4-butanedionato, 18-crown-6 = 1,4,7,10,13,16-hexaoxacycloocta-decane) were synthesized and characterized by elemental analysis, IR-, H-1 NMR-spectroscopy and X-ray diffraction analysis. The mutual arrangement of the beta-diketonate ligands relative to the barium atoms in 1 and 2 was found to be different. The nature of chemical interactions and charges distribution in 1 and 2 was investigated using an experimental-theoretical approach based on crystal (asymmetric unit-cell aspherical scattering factor) and molecular (whole-molecule aspherical scattering factor) invarioms within the framework of Bader theory. It was shown that the less favorable conformation of complex 2 is stabilized in the crystal by the higher energy of intermolecular interactions as compared to 1. The energy of intermolecular interactions (94.3 kJ/mol) in 1 was estimated by electron density topological analysis and agrees well with the experimentally obtained sublimation enthalpy (83.2 +/- 1.1 kJ/mol).

Automated summary

In this study, two new barium beta-diketonate complexes were synthesized and characterized using various analytical techniques. It was found that the mutual arrangement of the beta-diketonate ligands relative to the barium atoms differed between the two complexes, and the less favorable conformation was stabilized in the crystal through higher energy of intermolecular interactions.