In the search for volatile fluorinated compounds of potassium and rubidium, new complexes of the corresponding pivaloyltrifluoroacetonates (Ptac) with 18-crown-6 ether, K(18C6)(Ptac) (I) and Rb(18C6)(Ptac) (II), were synthesized. The compounds were characterized by elemental analysis, IR spectroscopy, and X-ray fluorescence analysis, and their structures were studied by X-ray diffraction in the range of 100–400 K (CCDC nos. 2429226–2429232 (I), 2429233–2429239 (II)). The complexes are isostructural and have an insular mononuclear structure, with M...H and M...C contacts involving the tert-butyl group between fragments, forming chains. The thermal expansion tensors are elongated along this direction. X-ray diffraction analysis showed that the rubidium cation in such a complex can complete its coordination sphere with a solvent molecule (chloroform, CCDC no. 2429240 (IIs)). For I, II, and IIs, Hirshfeld surfaces were analyzed and a search for pseudoperiodicity in the crystal packings was carried out by the translational sublattice method. Thermogravimetric analysis showed that, unlike the initial pivaloyltrifluoroacetonates, complexes I and II are volatile and promising for testing in gas-phase processes of thin-film material deposition.
Д. В. Кочелаков (Wed,) studied this question.