Cesium (+1) can add only one β-diketone moiety, which does not saturate its coordination sphere (CN = 8). Therefore in solid phase cesium diketonates form complex structures. F.e., cesium 2,2,6,6-tetramethylheptane-3,5-dionate Cs(thd) is not volatile and is rather ionic in nature. [84]
Cesium diketonates are synthesized by boiling the solution of β-diketone in the low-polar solvent with stoichiometric amount of CsOH.
Cesium acetylacetonate Cs(acac) (M=232.01) is white moisture sensitive powder. Though Cs(acac) has relatively low volatility, it is soluble in water and 2-ethoxyethanol (at least 0.2%), as well as in dimethylufoxide (DMSO).
The direct synthesis of Cs(acac) from cesium carbonate (Cs2CO3) and acetylacetone (Hacac) was reported. Strong ion association and ion pair formation was observed in Cs(acac), as well as in corresponding Li, Na, K, and Rb acetylacetonates, according to the molar conductance measurements, and comfirmed by 1H NMR measurements (in DMSO-d6). The extent of such ion association/ pair formation was lowest for Cs(acac) (compared to Li and other alkali metal analogues). [i] , [ii]
[i] C.R. Bhattacharjee, M. Bhattacharjee, M.K. Chaudhuri, S. Hnialum, J.Chem. Res., Synopses, 1991, no9, pp. 250-251 (12 ref.), « First synthesis of (acetylacetonato)rubidium(I), a direct route to (acetylacetonato)caesium(I) and evidence for strong ion association/ion-pair formation in M(acac) (M=Li, Na, K, Rb or Cs) »
[ii] C. Bhattacharjee, PhD Thesis, Nehu University , 1991, « Some contributions to the chemistry of peroxo compounds of zirconium, thorium, uranium and carbon, and alkali-metal acetylacetonates », http://dspace.nehu.ac.in/bitstream/1/5714/1/Peroxo%20compunds%20%28CR%20Bhattacharjee%29.pdf
Cesium acetylacetonate monohydrate Cs(acac)(H2O) was studied by IR spectroscopy. v(C=O) and v(C=C) bands at 1630 and 1510 cm-1 (correspondingly) were reported.[i]
[i] IG Zaitzeva, NP Kuzmina, LI Martynenko, Journal of Alloys and Comp., 1995 , Vol. 225, p.393-395, « The volatile rare earth element tetrakis-acetylacetonates »
Cesium hexafluoacetylacetonate Cs(hfac) (M=339.06) was reported to be moisture sensitive compound. It was suggested to be potentially applicable as Cs MOCVD precursor.
Cesium 2,2,6,6-tetramethyl-3,5-heptanedionate Cs(thd) (M=316.18 (or 316.35?) is white moisture sensitive powder, thermally stable at least to 260°C. Cs(thd) was synthesized by the reaction between cesium carbonate and 2,2,6,6-tetramethyl-3,5-heptanedione in carbon tetrachloride: Cs2CO3 + Hthd (CCl4) -> Cs(ptac) + CO2 + H2O (Yield 37%) [[i]]
Cs(thd) was reported to be not volatile (rather ionic in nature). Nevertheles, Cs(thd) was reported to be tested as Cs precursor for the deposition of K1-xCsxNbO3
by CVD[78]
[i]Т.Н. Мартынова, Л.Д. Никулина, С.В. Сысоев, А.А. Пастухов. Синтез и исследование лантаноидных комплексов β-дикетонатов. // Известия Сибирского отделения академии наук СССР. Серия химических наук. 1990. Вып. 6. С. 11–20
Cesium 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionate Cs(ptac) (M =) was reported to be less volatile and therm. stable compared to the double Cs-Y diketonate Cs[Y(ptac)4], however, still may be potentially applicable as Cs source for the CVD.
Cesium 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionate was synthesized from cesium carbonate and corresponding β-diketone:
Cs2CO3 + Hptac (CCl4, 60°C, 45min) -> Cs(ptac) + CO2 + H2O