Polyaminocarboxylate Ligands

Ring inversion in [Ruff/ -CgHgjfL-alaninejCl] is fast on the NMR time scale, but epimerization is slow in aqueous solution. Replacement of the coordinated methyl ester of L-alanine in [Ru(f/-C6H6)(L-alaMe)Cl2] by 9-ethylguanine is faster than its hydrolysis.  

8 Inert-Metal Complexes Other Inert Centers 

Investigation of the solvolysis of the ruthenium(IV) complex [RuBr6] in aqueous media, in DMSO, and in DMF was complicated by parallel substitution and reduction. [RuBr ] is the product in concentrated 

DMSO proceeds through characterizable ruthenium(III) intermediates to yield, eventually, ruthenium(II) products.  

The possibility of dramaticaUy increasing reaction rates by microwaving is now well established. A useful application in ruthenium chemistry is the preparation of the 1,4,7-trithianonane complex [Ru(71)2] from hydrated ruthenium trichloride and ligand, which can be carried out in methanol in a microwave oven in a matter of seconds with a yield of 98 %. In the absence of microwave technology this reaction does not take place at all.  

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Figure 3 Expanded acyclic polyaminocarboxylates ligands for Galn and In111.

There are several methods used to conjugate DOTA and other polyaminocarboxylate ligands to biomolecules.140,141 The simplest method, commonly used in solid-phase peptide synthesis, is the... 

The oxidation state +3 of bismuth is of primary interest for radiotherapy applications. As such, various polyaminocarboxylate ligands have been investigated as chelates for 212Bi and 213Bi. 

Reactions of iron-polyaminocarboxylates with nitric oxide have already been covered, in Section 5.4.3.8 bi- and polynuclear complexes containing polyaminocarboxylate ligands will be found in Section 5.4.5.4 below. 

Polyaminocarboxylate ligands, effect on water exchange, trivalent lanthides, 42 60-61... 

B. Chromium(III) Alkyl Compounds Polynuclear Chromium(III) Complexes Polyaminocarboxylic Ligands... 

Tetradentate Polyaminocarboxylate Complexes As the following examples indicate, stereospecific formation of metal complexes with chiral tetradentate polyaminocarboxylate ligands do not always lead to the same absolute structures as that of the corresponding complexes with achiral ligands.171... 

Fig. 62. Aromatic polyaminocarboxylate ligands for ECL (top) and relative ECL emission for Yb111 complexes 10 5 M at pH 9.2 (bottom) R is the reference edta chelate.

Substitution of multidentate polyaminocarboxylate ligands on to Ln3+ can change the coordination number, the lability of coordinated water, and the mechanism of exchange as is the case for nine-coordinate [Gd(DOTA)I I2C)] for which k [ a (25°C) = 4.8x 106s-1, 48.8 kJ mol, ... 

The enhanced stability of the five-membered chelate rings relative to those of larger size is also apparent in the trend of the thermodynamic parameters for the complexation of trivalent cations by a homologous series of polyaminocarboxylate ligands (Rizkalla et al. 1988,1989, Choppin and Muscatello 1985). These systems were analyzed, as described in section 3.2, in terms of dAH where... 

D. B. Rorabacher, W. J. MacKellar, F. R. Shu, and S. M. Bonavita, Anal. Chem., 43, 561 (1971). Solvent effects on protonation constants, NH4OH, acetate, polyamine, and polyaminocarboxylate ligands in CH3OH—HjO mixtures. 

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