STUDY OF POTASSIUM, RUBIDIUM HEXAFLUOROACETYLACETONATES AND BY-PRODUCTS OF THEIR SYNTHESIS AND CRYSTALLIZATION

Complexes MI(hfac), where MI = K+, Rb+, $$\text{hfac}~=~\text{C}{{\text{F}}_{\text{3}}}\text{COCHCOCF}_{3}^{-}$$ (hexafluoroacetylacetonate ion) are synthesized and characterized (elemental analysis, IR spectroscopy, powder X-ray diffraction analysis). It is shown that in the synthesis of K(hfac) from an ethylacetate (EtOAc) solution of K2CO3 and Hhfac taken in a stoichiometric ratio, at the intermediate stage, EtOAc molecules come into the K+ coordination sphere, and {K2(hfac)2(EtOAc)}∞ crystals are formed. At room temperature EtOAc is removed, and the K(hfac) target product is obtained. The twofold excess of Hhfac results in a mixture of products in which adduct crystals with water and hydrated β-diketone {K2(H4hfpt)2(hfac)2(H2O)}∞ (H4hfpt = 1,1,1,5,5,5-hexafluoropentane-2,2,4,4,-tetraol) are present. Slow crystallization of Rb(hfac) in and L-shaped ampoule at 35-40 °C in chloroform leads to the formation of {Rb3(hfac)2(CF3COO)(ttpt)}∞ (ttpt = 2,4,6-tris(trifluoromethyl)tetrahydropyrane-2,4,6-triol) crystals, and at crystallization in a drop of the 1.1 M NaCl solution, {Na2Rb(hfac)3}∞ crystals are found. By thermogravimetry it is shown that rubidium hexafluoroacetylacetonate is thermally less stable than similar complexes of potassium and cesium.