P-Diketonate precursors

Fortunately, most of the P-diketonate precursors have quite good solubilities in a variety of solvents which opens many new combinations of precursors and solvents for stable delivery. Indeed many new combinations are under test. 

Zheng B, Goldberg C, Eisenbraun ET, Liu J, Kaloyeros AE, Toscano PJ, Murarka SR Loan JF, Sullivan J. In situ quadrupole mass spectroscopy studies of water and solvent coordination to Copper(II) P- Diketonate precursors implications for the chemical vapor deposition of Copper. MaterChem Phys. 1995 41 173-81. 

Fig. 3.4 Structures of superbase and P-diketone precursors for PIL extractants and IL diluent (Reprinted with permission from Ref. [91]. Copyright 2014 Elsevier Ltd)...

Recently ECL reactions of Ru(bpy)32+ with other reducing agents have been documented, such as various P-diketone and some methylene compounds that have cyano and carbonyl groups [40], Hence with further research, analytical applications should arise for many classes of compounds other than amines that can act as reductants, or electrochemical precursors of reductants, capable of reacting with Ru(bpy)33+ to produce ECL. 

The interaction of the metal alkoxides with the salts of carboxylic acids or with p-diketonates of other metals is especially attractive for the synthesis of bimetallic molecular precursors in the cases, when the preparation of the alkoxide of the other metal is somehow hindered or it is insoluble or irreactive under the conditions applied. This method has been widely used for the sol-gel preparation of HTSC materials (because of low solubility and reactivity of Cu(OR)2) and lead-containing ferroelectrics (in the view of difficult synthesis and low stability of Pb(OR)2). It should be mentioned that the reaction between a metal alkoxide and a functional derivative does far not always lead to the formation of a mixed-ligand bimetallic complex ... 

Figure 4.42. Molecular structures of commonly used CVD precursor classes. Shown are (a) metal p-diketonate (acetylacetonate, acac) complex to grow a metal oxide film (H2 as the coreactant gas yields a metal film) (b) a heteroleptic (more than one type of ligand bound to the metal) p-diketonate complex to yield a Cu film the ancillary ligand helps prevent oligomerization, enhancing volatility (c) various types of complexes to deposit metallic, oxide, nitride, or oxynitride films (depending on coreactant gas(es) used - respective ligands are p-ketoiminato, p-diketiminato, amidinato, and guanidinato (d) a metal azolato complex commonly used to deposit lanthanide metal thin films.

Template reactions between malonaldehydes and diamines in the presence of copper(II), nickel(II) or cobalt(II) salts yield neutral macrocyclic complexes (equation 15). Both aliphatic and aromatic diamines can be used. In certain cases, non-macrocyclic intermediates can be isolated and subsequently converted into unsymmetrical macrocyclic complexes by reaction with a different diamine (Scheme 11). These methods are more versatile and more convenient than an earlier template reaction in which propynal replaces the malonaldehyde (equation 16). This latter method can also be used for the non-template synthesis of the macrocyclic ligand in relatively poor yield. A further variation on this reaction type allows the use of an enol ether (vinylogous ester), which provides more flexibility with respect to substituents (equation 17). The approach illustrated in equation (15), and Scheme 11 can be extended to include reactions of P-diketones. The benzodiazepines, which result from reaction between 1,2-diaminobenzenes and P-diketones, can also serve as precursors in the metal template reaction (Scheme 12). The macrocyclic complex product (46) in this sequence, being unsubstituted on the meso carbon atom, has been shown to undergo an electrochemical oxidative dimerization (equation 18). ... 

In the laboratory of A. Millar, the convergent enantloselective synthesis of CI-981, a potent and tissue-selective Inhibitor of HMG-CoA reductase was achieved. The central tetrasubstituted pyrrole ring was prepared via the Paal-Knorr pyrrole synthesis. The required 1,4-diketone precursor was efficiently prepared by the Stetter reaction between p-fluorobenzaldehyde and an unsaturated amide. Interestingly, the A/-benzyl thiazolium chloride catalyst afforded only the benzoin condensation product and none of the desired diketone. However, when the A/-ethyl thiazolium bromide catalyst was employed, under anhydrous and concentrated reaction conditions, the 1,4-diketone was formed in good yield. The authors also noted that the simple dilution of the reaction mixture resulted in a dramatic increase in the formation of the undesired benzoin condensation product. 

Most metal alkoxides are very reactive toward hydrolysis and condensation. They must be stabilized to avoid precipitation. The chemical control of these reactions is currently performed by adding complexing reagents that react with metal alkoxides at a molecular level, giving rise to new molecular precursors of different structure, reactivity, and functionality. Chemical modification is usually performed with hydroxylated nucleophilic ligands, such as carboxylic acids or P-diketones. In most cases complexation by XOH species can be described as a nucleophilic substimtion, as follows ... 

Strongly complexing P-diketones are currently employed to stabilize highly reactive metal alkoxides, such as W(OEt)6 [25]. Aluminum sec-butoxide, modified by ethylacetoacetate (etac), appears to be quite attractive as a precursor for the sol-gel synthesis of multicomponent ceramics, such as cordierite. Al(OsBu)2(etac) is more soluble and less reactive than the corresponding alkoxide [26]. 

Tumipseed, S. B., Barkley, R. M., and Sievers, R. E., Synthesis and characterization of alkaline-earth-metal P-diketonate complexes used as precursors for chemical vapor deposition of thin-film superconductors, Inorg. Chem., 30, 1164 (1991). 

Sirio, C Poncelet, O., Hubert-Pfaizgraf, L. G., Daran, J. C., and Vaissermann, J., Reactions between copper p-diketonates and metal alkoxides as a route to soluble and volatile copper(II) oxide precursors Synthesis and molecular structure of Cu4( J-3,n -0C2H40iPr)4(acac)4 and (acac)Cu(p-OSiMe3)2Al(OSiMe3)2, Polyhedron, 11, 177 (1992). 

Following the postulated biogenetic pathway (see Scheme 3), a chemical in vitro imitation, aiming at a biomimetic first synthesis of naphthyl isoquinoline alkaloids, had to consist of essentially four crucial steps (1) synthesis of suitable P-polycarbonyl precursors, (2) their primary cyclization to monocyclic diketones like 31 or 32, (3) the further differentiation to naphthalenes and isoquinolines, and (4) their mixed coupling to the complete natural alkaloids. 

GrazieUa M, Rosalia L, Francesco C, Frogala LI. New thermally stable and highly volatile precursors for lanthanum MOCVD synthesis and characterization of lanthanum P-diketonate gjyme complexes. Inorg Chem 1995 34(25) 6233-4. 

III-V nitrides (InN, GaN and AIN) are made by CVD using (CH3)3M (M=In, Ga and Al) and NH3 as precursors [6]. HgCdTe, which is used in infrar (IR) detectors, is made by the reaction of the dimethyl derivatives of the metals [7]. PbSnTe is also synthesized by CVD [8]. High-quality thin films of superconducting YBa CUjO,. have been prepared by metal organic chemical vapour deposition (MOCVD) techniques using p-diketonate derivatives of Y, Ba and Cu as precursors [9]. 

T. Athar, O.H. Jeong and S. Sang 11, Stable heterometahic huorinated P-diketonate alkoxocomplexes as precursors for Er-doped luminescence materials, Inorg. Chim. Acta., vol. 358, no. 15, pp. 4541-4547,2005. 

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