The structures of two Ba(II) chelates of beta-diketonates have been de
termined; one is mononuclear and the other is multinuclear. The Ba(II)
chelate of the anion of 2,2,6,6-tetramethyl-3,5-heptanedione (thd) re
crystallized from pentane formed monoclinic crystals, space group I2/a
. with dimensions a =24.365(9) angstrom, b =21.174(10) angstrom, c = 4
8.486(16) angstrom, beta = 100.98(3)degrees, and Z = 8. This structure
was determined to be a beta-diketonate deficient pentanuclear complex
with the formula Ba5(thd)9(H2O)3(OH). Both beta-diketonate and water
ligands act as bridges between barium ions in this structure, resultin
g in a thermally unstable compound. A new mononuclear anionic Ba(II) c
helate of 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate (hfa) has been syn
thesized. X-ray diffraction analysis of the monoclinic (space group C2
/c) crystals gave a unit cell of dimensions a = 22.379(7) angstrom, b
= 12.143(3) angstrom, c = 34.800(8) angstrom, beta = 102.22(2)degrees,
and Z = 8; its structure was determined to be (ethylenediamine-H-2)1.
5[Ba(hfa)5].C2H5OH. The thermal properties of (enH2)1.5[Ba(hfa)5].C2H5
OH were investigated by thermogravimetric analysis. It was determined
that this mononuclear anionic complex is volatile and thermally stable
when compared to previously reported Ba(II) beta-diketonate complexes
.