Tetrakis acetylacetonate complex

Among the chelated species, octacoordination is often encountered. The tetrakis-acetylacetonate complex of U(IV) (a-form) and Ce(IV) are isostructural. A two-dimensional X-ray analysis showed a slightly distorted square antiprismatic geometry [109—111) for Ce(acac)4 belonging to space group P2i/c [Ctn] with an average Ce—O (acac) bond length of 2.40 A and an <0—Ce—0 of 72°. The a-form of Th(acac)4 is found to be isomorphous (770) with Ce(acac)4 (Th—0=2.41 A)... 

Some seemingly simple zirconium salts are best regarded as essentially covalent molecules or as complexes examples are the carboxylates, Zr(0C0R)4, the tetrakis(acetylacetonate), the oxalate and the nitrate. Like its Ti analog, the last of these is made by heating the initial solid adduct of N205 and N204 obtained in the reaction... 

Thallium, tetrakis(acetylacetone)-stereochemistry, 94 Thallium, triaquatrinitrato-structure, 97 Thermochromism, 470 Thiocyanato complexes linkage isomerism, 184 Thiocyanic acid metal extraction from, 540 Thioethers complexes chirality, 199 formation... 

Cerium tetrakis(acetylacetonate), 1114 Cesium complexes crown ethers, 40 Chevrel phases, 1321 Chlorella vulgaris nitrate reductase structure, 1438 Chlorine cations... 

Rhodium, tetrakis(trimethylphosphine)-reactions, 4, 926 Rhodium carboxylates, 4,903 chemotherapy, 4, 903 Rhodium complexes, 4. 901 acetylacetone synthesis, 2, 376 alkylperoxo... 

Titanium, tetrakis(trimethysilyl)oxy-, 3, 334 Titanium, tetranitrato-stereochemistry, 1,94 Titanium, triaquabis(oxalato)-structure, I, 78 Titanium, tris(acetylacetone)-structurc, 1,65 Titanium alkoxides oligomeric structure, 2,346 synthesis ammonia, 2, 338 Titanium chloride photographic developer, 6,99 Titanium complexes acetylacetone dinuclear, 2, 372 alkyl... 

Cerium(IV) forms tetrakis complexes with y3-diketonates. Two monoclinic polymorphs are known for [Ce(acac)4] Q -[Ce(acac)4] and j0-[Ce(acac)4]. The a-form has been isolated after reaction between cerium(IV) hydroxide and an excess of acetylacetone (Matkovic and Gr-denic, 1963 Titze, 1974). Addition of benzene to the same reaction mixture resulted information of the jS-form (Titze, 1969) (fig. 16). The formation of the a- or /3-form is solvent dependent. Behrsing et al. (2003) obtained o -[Ce(acac)4] by aerial oxidation of [Ce(acac)3(H20)2] in dichloromethane, and j0-[Ce(acac)4] by the same reaction in toluene. In both cases, one has to made sure that besides [Ce(acac)3(H20)2] an excess of acetylacetone is present in the reaction mixture. Attempts to convert the jS-form into the Q -fonn by reciystallization in dichloromethane, resulted in significant reduction of cerimn(IV) to cerium(III). The coordination polyhedron of cerium(IV) in o -[Ce(acac)4] has both been described as a distorted square antiprism (Titze, 1974), a dodecahedron (Allard, 1976) or a bicapped square antiprism (Steffen and Fay, 1978). The coordination polyhedron in /3-[Ce(acac)4] is a square antiprism (Allard, 1976). The main difference between the a- and the /3-form is the more pro-notmced folding of the acetylacetonate ligand in the /3-form. Neutralization of a ntixture of... 

The volatility of the j8-diketonate complexes can also be increased by formation of the tetrakis complexes, because the latter are mononuclear. The first volatile heterobimetallic compound was the ionic Cs[Y(hfac)4], which Lippard (1966) sublimed without decomposition both in air and in vacuum. Addition of alkali metal acetylacetonate to [R(acac)3] complexes results in the formation of volatile M[R(acac)4] complexes (M = Li, Na, Cs) (Zaitseva... 

---