Metal trifluoroacetates

First structural evidence for the formation of heterobimetallic Ln/Al complexes in carboxylate-based catalytic systems was obtained from the reaction of homoleptic rare-earth metal trifluoroacetates with equimolar amounts of z -Bu2A1H and EtsAl, respectively [132], Alkylated yttrium, neodymium, and... 

Enhancement by strong acids such as TFA is a general feature of oxidations with metal acetates. Metal trifluoroacetates in TFA are much more powerful oxidants (electrophiles) than the corresponding acetates in acetic acid. Activation of the metal oxidant in TFA has been observed with co-balt(III)217 249,259,27S 276 manganese(III),237,275 lead(IV),277-281 thallium-(III),282-287 cerium(IV),288 289 and copper(II).290 Similarly, the electrophilic properties of copper(I)291 and mercury(II)292 acetates are strongly enhanced by replacement of acetate by trifluoroacetate. It has been proposed217,276 that the potent oxidizing properties of Co(III) trifluoroacetate are due to ionization to the cationic Co(III) species,... 

This section will describe the range of preparative methods that have been used to obtain metal trifluoroacetates, each being illustrated by selected examples. However, no attempt will be made to give a comprehensive list of the compounds synthesized by any particular route. 

Metal trifluoroacetates are used as catalysts in several industrial processes. The use of [(7i-allyl)Ni(02CCF3)2]2 in the stereospecific polymerization of butadiene has been studied in some detail 59, 60, 166,... 

During these reactions, transient charge-transfer absorption is observed this is ascribed to the EDA complexes of the arene donors with the metal trifluoroacetate [113], (Eq. 26) ... 

Preparation of Superconducting Oxide Films from Metal Trifluoroacetate Solution Precursors... 

GUPTA ET AL. Oidde Films from Metal Trifluoroacetate... 

A number of other studies involving metal trifluoroacetates are covered in the appendix at the end of this chapter (p. 178), together with some on metalloidal and non-metal trifluoroacetates. 

Some other studies involving metal trifluoroacetates are mentioned in the Bibliography at the end of this chapter (p. 169), together with a few on metalloidal and non-metal trifluoroacetates and alkali-metal chlorodi-fluoroacetates. The green polychelate (6) can be obtained by treatment of the JViV -diacylhydrazine CF,-CO-NH-NH-CO-CFa [from OF.-COjEt -I- NjH -+ CFa-CONHNHj (CFsCO)jO -I- CF,CONHNH, CFs CO-NH-NH CO-CFa] with aqueous cupric acetate. ... 

The mechanism of the decomposition reaction into metal fluorides has not been elucidated so far. In the first place, metal trifluoroacetates themselves have been relatively less studied among the salts of carboxylic acids. Synthesis and properties of only a few metal trifluoroacetates have been reported (Killings, 1974 Khristov, 1998 Tada, 1999). Thermogravimetry-mass spectrometry (TG-MS) analysis has been carried out to examine the deconposition reaction oflanthanum trifluoroacetate (Eujihara, 2000b). The reaction suggested is... 

Rtlssel C. A pyrolytic route to fluoride glasses. I. Preparation and thermal decomposition of metal trifluoroacetates. J. Non-Cryst. Solids 1993 152 161-166 Rywak A.A., Burlitch J.M. Sol-gel synthesis of nanocrystaUine magnesium fluoride its use in the preparation of Mgp2 films and MgF2-Si02 composites. Chem. Mater. 1996 8 60-67 Saad M., Poulain M. Fluoride glass synthesis by sol-gel process. J. Non-Cryst. Solids 1995 184 352-355... 

The driving force in the formation of complex phases is their thermodynamic stability under experimental conditions. When the desired materials have relatively large stability range in relation to both temperature stabiUty and chemical composition, such as alkaline metal rare earth fluorides, M REp4, a variety of precursor systems can be used successfully for their preparation. In particular, metal trifluoroacetates have been successfully used for this purpose [142]. For preparation of micropowders, a successful strategy may be to produce first... 

This route, shown in Scheme 1.2, also starts from metal alkoxides, which are reacted in solution with, e.g., trifluoroacetic acid to form metal trifluoroacetate sol. This can be... 

The precursor solutions or dried gels containing metal trifluoroacetate complexes are subject to heat treatments at temperatures higher than 300 °C, which is a typical decomposition temperature to form metal fluorides. Exact decomposition temperatures depend on the kind of metal elements involved [19, 22]. At much higher temperatures, metal oxyfluoride or metal oxide materials are also obtained. However, not all the metal elements form fluoride compounds in this process. At least, metal elements with electronegativity less than 1.5 can form metal fluorides through the decomposition in the air. Alkali, alkaline earth and rare-earth fluorides are therefore successfully obtained. Heat-treatment atmospheres sometimes influence the decomposition behaviour of trifluoroacetate precursors [20]. 

The decomposition reaction of the metal trifluoroacetates involves the generation of gaseous phases such as (CF3C0)20, CF3COF and COF2 [19] in addition to the dehydration and the vaporization of the organic components. It seems that F can be supplied from these organofluorine species because, in the presence of water, F ions can be supplied by... 

C. Russel, A pyrolytic route to fluoride glasses. I. Preparation and thermal decomposition of metal trifluoroacetates, J. Non-Cryst. Solids, 152, 161-166 (1993). 

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