Metal atoms with acetylacetone

Zrlv and HfIV porphyrins are prepared from metal acetylacetonates and porphyrin, but the product depends on the solvent and the work-up procedure.17 Mlv(Por)(acac)2, Mlv(Por)-(acac)(OPh) and Mlv(Por)(02CMe)2 are all interconvertible, and the additional ligands are on the same side of the porphyrin (Scheme 10). The acetato groups serve as bidentate ligands and the metal atom is centred in a distorted square antiprism.21 Zr(OEP)(02CMe)2 and Hf(0EP)(02CMe)2 are isodimensional with M—Npor x 2.26 A, M—O a 2.28 A and A(N4) x 1 A. 

Unlike Si and Ge acetylacetonates (acac), in which the central M atom is hexacoordinated, the coordination number of the Sn atom in RSn(acac)3 is 7173. Hexacoordinated Si, Ge, Sn, Pb complexes with tropolone (Tp) are known. Tp4M molecules, where the metal atom is octacoordinated for M = Sn, Pb or hexacoordinated for M = Si, Ge, are of particular interest. The latter compounds correspond to the structure Tp3M+Tp- and exist as salts or ion pairs174. 

Complexes with the composition M(dike)2 usually exist as oligomers, so that the metal atoms are coordinatively saturated. For example, the acetylacetonate complexes of Ni, Zn, and Mn exist in the solid state as trimers of varying stracture, with bridging /3-diketonate groups (20). The extent of oligomerization varies with the metal cation forms a... 

Typical square-planar rhodium-olefin complexes such as acetylacetonates (48) have a stoichiometry of two coordinated olefins per metal-atom. Since chelating olefins are bidentate in their cationic rhodium biphosphine complexes, it would be surprising if bis-olefin complexes were never found under hydrogenation conditions. It seems clear, in fact, that they can be the major coordinated species under certain conditions. Thus examples of 2 1 rhodium enamide complexes with biz-diphenyl-phosphinopropane have been observed (49), although the majority of cases involve a8-unsaturated acids co-complexed with DIOP. 

By functioning as Lewis acids, many beryllium compounds attain maximum coordination of the metal atom. Thus the chloride forms etherates, Cl2Be(OR2)2, and complex ions such as BeF and [Be(H20)4]2+ exist. In chelate compounds such as the acetylacetonate, Be(acac)2, four approximately tetrahedral bonds are formed with the C—O and Be—O bond lengths equivalent. 

Very many coordination compounds are known between metal atoms and bifunctional organic molecules, where the binding is partly normal covalent links and partly coordinate links for example, copper acetate solution mixed with acetylacetone gives a blue compound that is non-ionized and can be vaporized unchanged. It can be formulated ... 

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