Dipivaloylmethanato complex

Some work has also been reported on a californium dipivaloylmethanato complex, where the volatility of the complex was compared to complexes of other lanthanides and actinides [151]. These tracer studies suggested that the californium complex deposited at lower temperatures than the americium or plutonium complexes. 

In 1989, Isayama and Mukaiyama reported a related Co-catalyzed coupling reaction that employs a,b-unsaturated nitriles, amides, and esters with PhSiLb as a hydrogen source [9]. Cobalt-bis(diketonato) complex, Co(II)(dpm)2 [dpm = bis(dipivaloylmethanato)] (5mol%), exhibited high catalytic activity at 20 °C in the coupling of excess acrylonitrile and ben-zaldehyde to provide b-hydroxy nitrile 4 in 93% yield (syn anti = 50 50) (Scheme 5). N,N-Dimethylacrylamide and methyl cinnamate both reacted... 

The reactions of 1,8-naphthyridine with tris(dipivaloylmethanato)lan-thanide to form the appropriate complexes are exothermic.112... 

Acetylacetonate and substituted acac derivatives are attractive because of their versatility and stability under normal conditions, as well as their ability to deposit metals cleanly under relatively mild conditions . The dipivaloylmethanato (dpm) derivative from stable and volatile lanthanide compounds, e.g. Lu(dpm)3, have in the gas phase D3 symmetry of the coordination polyhedron. According to Kepert s model, bidentate ligands can be approximated by diatomic molecules and it is completely predictable for the structures of these complexes in the gas phase, but the solid-state structures might be different. 

A variety of metals have been used to promote the Baeyer-Villiger oxidation. Using catalytic metal complexes has allowed the use of inexpensive H202 or 02. Yamada and co-workers reported the use of a Ni(II) complex with 02 to promote the Baeyer-Villiger oxidation on simple ketones. In this work was reported the use of (dipivaloylmethanato)-nickel(II) to be a good complex with isovaleraldehyde or benzaldehyde under an atmosphere of 02 to provide good conversions of ketones to lactones or esters. These conditions proved to be amenable to promote the Baeyer-Villiger oxidation of a variety of ketones in 33-96% yield and is exemplified by the conversion of ketone 51 into lactone 52,29... 

Tris(dipivaloylmethanato)technetium(IIl) (dipivaloyl methane = 2,2.6,6-tetra-methyl-3,5-heptancdione) was obtained by refluxing a mixture of dipivaloylmcthane. (NH4)7 TcClft], sodium methoxide and zinc powder in methanol. The red solid is readily oxidized at A /2 = + 0.12 V vx SCE to the cationic Tc(lV) complex. Tris(trifluoro-acetylacctonato)technctium(III) (trifluoroacctylacetone CF3-CO-CH2-CO-CH3) and tris(hexafluoroacetylacetonato)technetium(III) (hexafluoroacetylacetonc CF3-CO-CH2-CO-CF3) were prepared by reaction of the ligands with NH4TCO4 in refluxing ethanol and reduction with dithionite. These complexes are much more difficult to oxidize [423]. 

The stereochemistry of tetrakis (dipivaloylmethanato)niobium(iv) has been shown by X-ray analysis to be the first example of a M(bidentate)4 complex whose stereochemistry is based on an idealized square antiprism (38)." The first Ta pure n.q.r. spectra have been detected in Ta2X o (X = Q or Br) as part of a detailed n.q.r. study of such dimers. ... 

Tetrakis(dipivaloylmethanato)niobium(iv), [Nb (Bu CO)2CH 4] has been prepared by treating NbCl4 with dipivaloylmethane in MeCN containing EtjN. X-Ray crystallographic studies have shown that this compound is the first example of an M(bidentate)4 complex whose stereochemistry is based on an idealized D4 square antiprism (38). In the absence of oxygen and moisture, [Nb (Bu CO)2CH 4] affords stable, very weakly conducting solutions in CH2CI2 which contain the monomer. ... 

Non-bonded interactions [632-634] were included in the same way as was used first for the modeling of cobalt(III) complexes [130] and more recently for a wide range of transition metal compoimds [95, 104, 125]. That is, standard models with M-L harmonic bond-stretching terms were used, but the L-M-L harmonic terms were deleted and L... L non-bonded interactions were used in their place. In the first of these studies, on lanthanoid shift reagents, two seven-coordinate europium(III) and ytterbium(III) complexes, [Eu(dipivaloylmethanato)3(quinuchdine)] and [Yb (acetylacetonato)3(H20)] (Figure 15.5), were modeled [632]. The structures of these complexes were well reproduced. In a subsequent study, these complexes and [Eu (dipivaloylmethanato)3(DMSO)] were studied with the same force field, while the random incremental pulse search method was used to locate all potential coordination geometries [633]. 

The complex formed from the diketone shown in Figure 1.26(a) and europium(III), i.e., the tris(dipivaloylmethanato)europium(III) complex [Eu(DPM)3], is one such reagent which interacts with alcohols or amines to... 

Miscellaneous.— Isomerization of [Mo02(dipivaloylmethanato)2] is definitely intramolecular, but it is not possible to choose between a purely non-dissociative twist and a mechanism in which one or both of the bidentate ligands imdergoes partial dissociation to become unidentate. The activation energy for this isomerization is 17.0 kcal mol the frequency factor is gi2.6 454 Interconversion of isomers of octahedral molybdenum(v) complexes of the type MoOL LlX is fast. ... 

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