Lanthanide complexes carboxylates

In many cases, the inflexions present in the plots of AH and AS vs. atomic number compensate, leading to much smoother curves for corresponding plots of AG or K. Examples of this type of behaviour are shown in reference 405, where values of AG, AH and AS for lanthanide complexes with edta and related ligands are plotted. Extensive lists of association constants for edta-type and other carboxylate ligands have been given.414,415... 

Lanthanide complexes with carboxylic acids, amino acids and phosphorus acids [22-24].265... 

The complexes may also be prepared by the addition of a solution of carboxylic ligand to an equivalent amount of (i) a lanthanide carbonate [28], (ii) hydroxide [29] or (iii) oxide [30] with a slight excess of the latter. The insoluble part is filtered and the filtrate evaporated to obtain crystalline complex. Anhydrous lanthanide complexes of small chain carboxylic acids may be prepared by (i) the dissolution of lanthanide carbonate in excess of the carboxylic acid, followed by heating to obtain complete dissolution of the suspension and partial evaporation of the solution to obtain the crystals [31], (ii) anhydrous lanthanide is converted into the corresponding monochloroacetate by the addition of an excess of monochloroacetic acid, followed by heating under reflux at reduced pressure for 2 h. Then ether is added to precipitate the salt [32], (iii) the addition of dimethyl formamide and benzene to lanthanide acetates and distillation of the water azeotropes to obtain anhydrous complexes. The last procedure yielded lighter lanthanide complexes solvated with dimethyl formamide [33], The DMF may be removed by heating in a vacuum at 120°C. 

If one carboxylic acid side chain in H4DOTA is replaced by hydrogen, the resulting acid, H3DO3A, forms neutral lanthanide complexes. In solution, they are believed to have two water molecules coordinated so that the... 

Mato-lglesias, M., Rodrrguez-Blas, T., Platas-lglesias, C., etal. (2009) Solution structure and dynamics, sta-biUty, and NIR emission properties of lanthanide complexes with a carboxylated bispyrazolylpyridyl ligand. Inorganic Chemistry, 48, 1507. 

Solution dynamics of complexes of EGTA (3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazate-tradecanedioate) have been studied a change in coordination number from 10 to eight is believed to occur across the lanthanide series. " Binuclear La and Y complexes of 9,14-dioxo-l,4,7,10,13-pentaaza-l,4,7-cyclopentadecanetriacetic acid have nine-coordinate lanthanides. Lanthanide polyamine carboxylates and complexes of macrocycles with pendant amide groups show promise as catalysts for RNA cleavage such complexes have considerable stability in aqueous... 

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