Structural chemistry carboxylates

Numerous compounds of Cd with mono- and difunctional carboxylic acids have been prepared and studied. Special ll3Cd solid-state NMR studies on single crystals of some simple Cd carboxylates have been reported, with a short review of the structural chemistry of these compounds.270,271... 

Recent investigations provide new insight on the structural chemistry of dissolved organic matter (DOM) in freshwater environments and the role of these structures in contaminant binding. Molecular models of DOM derived from allochthonous and autochthonous sources show that short-chain, branched, and alicyclic structures are terminated by carboxyl or methyl groups in DOM from both sources. Allochthonous DOM, however, had aromatic structures indicative of tannin and lignin residues, whereas the autochthonous DOM was characterized by aliphatic alicyclic structures indicative of lipid hydrocarbons as the source. DOM isolated from different morphoclimatic regions had minor structural differences. 

One important chemical result from the ESCA studies involves the formation of surface carboxylates. Upon transfer of the monolayer to silver, the formation of a carboxylate could be detected by the production of a single peak in the oxygen Is line due to equivalent oxygens in the carboxylate structure. Since the oxygen spectrum of the monolayer yields near stoichiometric C-0/C==0 ratio of 1, the carboxylate is not detectable. Studies with monolayer films of cadmium arachidate indicated detectability of the carboxylate as a single carbon Is peak. The lack of the formation of this interfacial carboxylate indicates the strength (or weakness) of surface chemistry which occurs on this silver surface as prepared. 

This chapter will cover the synthetic, structural, and solution chemistry of rare earth complexes with carboxylic acids, polyaminopolycarboxylic acids, and amino acids, with an emphasis on their structural chemistry. As the carboxylate groups play the key roles in the metal-ligand coordination bonding in these complexes, we will start the chapter with the coordination chemistry of rare earth-carboxylic acid complexes, followed by rare earth-polyaminopolycarboxylic acid and rare earth-amino acid coordination chemistry. Owing to length limitations, an exhaustive citation of the large amount of research activities on the subjects is not possible. Instead, only selected examples are detailed to highlight the key features of this chemistry. 

Structural Chemistry of Rare Earth Complexes with Carboxylic Acids... 

In a review of the stereochemistry of a-hydroxycarboxylate complexes, Tapscott includes the structural chemistry of complexes that contain ligands in which a sulfur atom is attached to a carbon a to a carboxylic group. This includes both a-mercapto and a-thioether groups. Lists of structural bonding parameters for a-thiocarboxylate complexes are given together with parameters for chelate rings. 

The structural chemistry of organotin carboxylates has been thoroughly reviewed [419, 420] and only a brief survey of self-assembled supramolecular systems will be presented here. 

A fulvic acid of number average molecular weight 1000 can yield as many as 30 different substituted mononuclear phenol-carboxylate structures in a mild oxidative degradation which accounts for 30% of the mass of the sample. Because only a small fraction of these structures would be needed to make a polymer of MW = 1000, it is clear that the fulvic acid is a complex mixture, yet the aliphatic components have not so far been considered. It may be asked if efforts should not concentrate on the resolution of the mixture, regardless of how difficult that task may be. However, the task in understanding natural system chemistry would then require modeling the interactions that occur in the mixture, which is, in my opinion, more difficult than studying them directly. 

Clearly, the coordination ability of an amino acid depends on its specific form, wifh carboxylate and amino groups, and the side chain each potentially coordinating. This feature in turn is critically dependent on the pH condition, ft is thus convenient to present the chemistry of lanthanide-amino acid complexes according to the pH conditions under which the synthesis is carried out. Specifically, the synthetic and structural chemistry of lanthanide complexes with amino... 

Three reviews on aspects of structural chemistry were noted on organomagnesium compounds, on organotin carboxylates, and another of Melnik s systematic studies of bond parameters u g the CX3XI files, of coordination con unds of ihenium.3... 

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