Carboxylic acids reaction with metal complexes

Benzohydroxamic acid dioxouranium complexes, 507 metal complexes, 506, 507 as metal precipitant, 506 Benzohydroxamic acid, iV-methyl-metal complexes, 506 Benzohydroxamic acid, N-phenyl-metal complexes, 507 reactions with carboxylic acids, 507 as metal precipitant, 506 titanium complexes, 506 Benzohydroxamic acid, A -(o-tolyl)-as metal precipitant, 506 Benzohydroxamic acid, N-wi-tolyl-p-methoxy-metal complexes, 506 Benzoic acid, dihydroxy-beryllium(II) complexes, 481 Benzoic acid, o-mercapto-esters... 

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 ... 

These pathways represent competing processes, and their relative contributions in the reactions of metal complexes with carboxylic acids are influenced by several factors. The structure of the alkyl group is important in oxidations with Mn(III) and Co(III), since reaction (261) is a concerted process with these oxi-... 

Carboxylate complexes are often synthesized by refluxing the acid with the metal salts (such as carbonate, sulfate, oxide, etc.), or by reaction of the sodium or silver salt of the acid with the metal halide. Insertion of CO2 into a-bonded organotransition metal species has also been used to generate carboxylate complexes, as has exchange reactions with metal alkoxides (see Section 3.3). 

The reaction of carboxylic acid chlorides with low-valent metal complexes leads to the formation of acyl complexes, which can undergo decarbonylation to give a-bonded metal alkyls, alkenyls, or aryl complexes. This decarbonylation has been used to synthesize aiylsilanes from aryl acid chlorides in the presence of nickel(0) or palladium(0) complexes as catalysts. Similarly, acyl cyanides undergo decarbonylation with palladium(O) complexes to afford nitriles or alkenes, depending on the substrate. ... 

When a Br nsted base functions catalytically by sharing an electron pair with a proton, it is acting as a general base catalyst, but when it shares the electron with an atom other than the proton it is (by definition) acting as a nucleophile. This other atom (electrophilic site) is usually carbon, but in organic chemistry it might also be, for example, phosphorus or silicon, whereas in inorganic chemistry it could be the central metal ion in a coordination complex. Here we consider nucleophilic reactions at unsaturated carbon, primarily at carbonyl carbon. Nucleophilic reactions of carboxylic acid derivatives have been well studied. These acyl transfer reactions can be represented by... 

The second type of trinuclear compounds containing (M302(02CR)(,(H20)3] and obtained by the reaction of M(CO)6 (M = Mo, W) with carboxylic acids, features a similar triangle of M-M bonded metal atoms but this time capped on both sides by hj-O atoms (Fig, 23.8d). Complexes m which either one or both of these capping atoms arc replaced by /iy-CR, alkylidene. 

The observation that addition of imidazoles and carboxylic acids significantly improved the epoxidation reaction resulted in the development of Mn-porphyrin complexes containing these groups covalently linked to the porphyrin platform as attached pendant arms (11) [63]. When these catalysts were employed in the epoxidation of simple olefins with hydrogen peroxide, enhanced oxidation rates were obtained in combination with perfect product selectivity (Table 6.6, Entry 3). In contrast with epoxidations catalyzed by other metals, the Mn-porphyrin system yields products with scrambled stereochemistry the epoxidation of cis-stilbene with Mn(TPP)Cl (TPP = tetraphenylporphyrin) and iodosylbenzene, for example, generated cis- and trans-stilbene oxide in a ratio of 35 65. The low stereospecificity was improved by use of heterocyclic additives such as pyridines or imidazoles. The epoxidation system, with hydrogen peroxide as terminal oxidant, was reported to be stereospecific for ris-olefins, whereas trans-olefins are poor substrates with these catalysts. 

Oxidative addition of the O-H bond to transition metal complexes gives hydrido(hy-droxo), hydrido(alkoxo) or hydrido(carboxylato) complexes (Eq. 6.1), but web-characterized complexes obtained as primary products from the reaction of the compound, XO-H (XO-H = water, alcohol, and carboxylic acid) with late transition metals are quite rare [1]. Furthermore, the crystal stractures of very few complexes of this type have been reported. In this section we will survey late transition metal complexes resulting from activation of water, alcohol, and carboxylic acid. 

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