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 β-diketonate complexes with 18-crown-6 were synthesized. • The thermal properties and structures of these complexes have been studied. • The topological characteristics of the electron density in them have been investigated. • The enthalpy of sublimation of [Ba(adtfa) 2 (18-crown-6)] was measured by Knudsen method and evaluated through the energy of intermolecular interactions. • The barium complexes were found to differ by the arrangement of the CF 3 and Ad substituents in the coordination sphere. The new barium β-diketonate complexes with 18-crown-6 [Ba(adtfa) 2 (18-crown-6)] ( 1 ) and [Ba(adtfa) 2 (18-crown-6)](CDCl 3 ) 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-, 1 H NMR-spectroscopy and X-ray diffraction analysis. The mutual arrangement of the β-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).