Synthesis, crystal structure and thermal behaviour of Ba(hfa)(2)(Phen)(2) and the crystal structure of Ba-2(hfa)(2)(mu(2)-CF3COO)(2)(Phen)(4) (hfa=hexafluoroacetylacetonate, Phen=o-Phenanthroline)

Ba(hfa)(2)(Phen)(2) (I) was obtained by the interaction of Ba(hfa)(2) and P hen and by the reaction of metallic barium with hexafluoroacetylacetone and Phen. Crystal structures of I and the by-product, Ba-2(hfa)(2)(mu(2)-CF3CO O)(2)(Phen)(4) (II), were determined by single crystal X-ray diffraction. C omplex I has a mononuclear structure with four oxygen and four nitrogen ato ms in the coordination sphere of the central Ba2+ ion. The average distance s are: Ba-O (2.71 Angstrom) and Ba-N (2.89 Angstrom). Tn centrosymmetric di meric molecules of II, both barium ions are eight-coordinated as a result o f the coordination of one bidentate hfa-ligand, two bidentate Phen ligands and two oxygen atoms of both bridge tfa-ligands. The average distances of B a-O and Ba-N are 2.71 Angstrom and 2.91 Angstrom, respectively. The geometr y of the Ba coordination sphere and the packing in I and II are discussed. Thermal gravimetric analyses showed that I sublimed with the evolution of P hen and the formation of volatile Ba(hfa)(2)(Phen). (C) 1999 Elsevier Scien ce Ltd. All rights reserved.