Diketones, ligands

The / -diketonates demonstrate that, like platinum(II), platinum(IV) can bond to both carbon and oxygen atoms in the diketonate ligand. 

Maverick and coworkers have reported a number of square structures derived from /(-diketonate ligands (116). The dark green complex [Cu4(L12)4] is a representative example. This complex was obtained by reaction of the /(-diketone HL12 with [Cu(NH3) ]2+ in almost quantitative yield and has a diameter of about 14 A. The [Cu4(L12)4] square functions effectively as a host... 

Replacements of ferrocene-substituted p-diketone ligands, p-dik, in cyclooctadiene-rhodium(I) complexes [Rh(p-dik)(cod)] by 1,10-phenan-throline are characterized by large negative activation entropies, indicating the operation of the expected associative mechanism, although the... 

Acetylacetonates and Related Complexes (Table 6). Metal /3-diketonates and related functional derivatives have been extensively investigated in UV-P.E. spectroscopy. Their spectra are similar to those of the free j3-diketone ligands, whose spectral patterns can always more or less directly be traced back in the spectra of the metal complexes, of which they often represent the major and more characteristic part, d-... 

The tetrakis- 8-diketonate complexes of the lanthanides constitute an important stereoisomer in the dodecahedral geometry. The four diketonate ligands are found to span the four g-edges of the dodecahedron (Fig. 22) (146, 147). In other do-... 

The LSR itself consists of a lanthanide ion, commonly europium (Eu3 + ), praseodymium (Pr3+) or ytterbium (Yb3+), and three /1-diketone anions with alkyl or perfluoroalkyl groups Rl and R2 as ligands. Perdeuterated LSRs, which do not give H signals, are commercially available. Incorporation of chiral /J-diketone ligands, mostly derived from substituted camphors, allows chiral recognition. 

In 2003, Hayashi and his co-workers found that highly enantioselective rhodium-catalyzed allylic alkylation took place with l-aryl-2-propenyl acetates by using an achiral /3-diketonate ligand for the rhodium complexes in the presence of (diphenylphosphino)binaphthyloxazoline 60b. Fine-tuning of the /3-diketonate part resulted in enhancement in enantioselectivity up to 97% ee (Equation (49)). " ... 

Maverick. A.W. and Klavetter, F.E. (1984) Cofadal binuclear copper complexes of a bis(P-diketone) ligand. Inorg. Chem., 23, 4129 130. 

Many [M(dik)4] complexes are volatile, especially those that contain fluorinated diketonate ligands. Mass spectra and gas chromatographic behavior of several of these complexes have been studied (see Table 10). Isenhour and coworkers240 241 have employed fluorinated diketonates in mass spectrometric procedures for determination of Zr and Zr/Hf ratios in geological samples. The most intense peak in mass spectra of [M(dik)4] complexes is [M(dik)3]+. Sievers et al.242 have used gas chromatography of metal trifluoroacetylacetonates to separate Zr from Al, Cr and Rh. However, attempts to separate [Zr(tfacac)4] and [Hf(tfacac)4] by gas chromatography were unsuccessful. Zirconium and hafnium can be separated by solvent extraction procedures that employ fluorinated diketones.105 [M(dik)4] (M = Zr or Hf dik = acac, dpm, tfacac or hfacac) have been used as volatile source materials for chemical vapor deposition of thin films of the metal oxides.243,244... 

Several /3-diketonate complexes of the type [W(L-L)X2] (X = Cl, Br L = acac, 6-methyl-2,4-heptanedione, dibenzoylmethane) have been prepared from reaction of the j8-diketone ligands with WX5. The suggested cis stereochemistry, based on IR measurements, must be considered tentative. 

Further examples of the rare /8-diketone (as opposed to /8-diketonate ligand have been found, and the complexes [Zn(acacH)3] [InCl4] and [Zn(MeC0CH2C02Et)3][InCU] have been described.755... 

Reactions of the coordinated j8-diketonate ligand are those typical of aromatic ring systems176 with electrophilic substitution at the y carbon being favoured, e.g. reaction with nitric oxide.177... 

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