New calсium β-diketonate complexes: The monomeric complexes [Ca(PhCOCHCOCF 3) 2(15-crown-5)], [Ca(AdCOCHCOCF 3) 2(15-crown-5)] and the binuclear hydrated complex [{Ca(adtfa)(18-crown-6)(H 2O)}{Ca(adtfa) 3(H 2O)}(EtOH)]. Synthesis, characterization and crystal structure

Abstract

The preparation of the Ca-β-diketonate complexes with crown-ethers, [Ca(btfa) 2(15-crown-5)] ( 1), [Ca(adtfa) 2(15-crown-5)] ( 2), [Ca(adtfa) 2(15-crown-5)](C 6H 5CH 3) 0.5 ( 3) and [{Ca(adtfa)(18-crown-6)(H 2O)}{Ca(adtfa) 3(H 2O)}(EtOH)] ( 4) (btfa = 1,1,1-trifluoro-4-phenyl-butanedionato-2,4; adtfa = 1,1,1-trifluoro-4-(1-adamantyl)butanedionato-2,4; 15-crown-5 = 1,4,7,10,13-pentaoxacyclopentadecane; 18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane), is described. Complex 1 has been prepared from the reaction of metallic Ca with 2 eq. of Hbtfa and 1 eq. of 15-crown-5 in toluene; complex 2 has been prepared from the reaction of metallic Ca with 2 eq. of Hadtfa and 1 eq. of 15-crown-5 in ethanol. The solvated complex 3 was obtained by cooling of a toluene–hexane solution of 2. The hydrated complex 4 was prepared from the reaction of metallic Ca with 2 eq. of Hadtfa and 1 eq. of 18-crown-6, followed by addition of excess H 2O to the resulting reaction mixture. The all complexes were characterized by elemental analyses, IR-spectroscopy, NMR-spectroscopy, single-crystal X-ray diffraction methods, DSC and TGA. A single-crystal X-ray study of 1 and 3 has show that complexes 1 and 3 are monomeric and contain the calcium atom bonded with two β-diketonate ligands and one molecule of crown-ether. Complex 4, as shown by X-ray analyses, is an ion-paired solvated adduct, containing the cation {Ca(adtfa)(18-crown-6)(H 2O)} + and the anion {Ca(adtfa) 3(H 2O)} −. The monomeric complexes 1– 3 are volatile and thermally stable in the temperature range 100–260 °C. Complex 4 undergoes decomposition above 110 °C with consecutive loss of ethanol, H 2O, 18-crown-6 and some evaporization of 4.