Aminocarboxylate complexes

Many of the multidentate features observed for aminocarboxylate complexes of bismuth are evident in a small, diverse group of complexes involving hydroxyamine and aminoalkoxides ligands (Table XVI). Most of the examples in this section may be considered unique and represent unusual structural arrangements. 

Products of substitution of inosine and guanosine 5 -monophosphate for chloride or for water on ternary aminocarboxylate complexes such as [Pd(mida)(D20)], where mida = IV-methyliminodiacetate, or [Pd2(hdta)Cl2]2-, where hdta = 1,6-hexanediamine-A(7V,./V,./V,-tetraace-tate, is subject to mechanistic controls in terms of number of coordinated donor atoms and pendant groups and of the length of the chain joining the functional groups in the bis-iminodiacetate ligands. These factors determine the nature and stereochemistry of intermediates and the relative amounts of mono- and bi-nuclear products (253). 

The use of the steric crowding to tune the water exchange rate on poly-aminocarboxylate complexes of Gd " to its optimum value for MRI contrast... 

The activation of the normally inert methylene group of glycine by coordination to a transition ion has been recognized for many years. The substantial increase in the acidity of the methylene hydrogens has been directly confirmed by deuterium labelling experiments,451 and has also been shown to occur in other a-aminocarboxylate complexes of cobalt(III)451 456 and platinum(II).457... 

Using hexadentate tris[3-(2-pyridyl)pyrazol-l-yl]hydroborate (34) or tetradentate bis[3-(2-pyridyl)pyrazol-l-yl]dihydroborate (35) as a ligand, Ward and coworkers reported the preparation, characterization, and photophysical properties of a series of binary or ternary complexes of lanthanide(III) complexes with dibenzoylmethane anions (dbm) or nitrate anion as a co-ligand [58-60]. Sizeable NIR emission was detected for these pyrazolylborate-derived complexes of Nd(III), Pr(III), Er(III), and Yb(III) ions. They gave longer lifetimes of lanthanide luminescence than those of aminocarboxylate complexes due to the lack of C-H oscillators in close proximity to the lanthanide(III) ions in the pyrazolylborate complexes compared with that in the aminocarboxylate species. 

By far the most commonly used bleaching agents are aminocarboxylate complexes of iron(III). The potential of a simple iron complex redox system can be written as Eq. (93),... 

EDTA) ethylenediamine-iV,N,Af, Ar-tetraacetate " stabiUty constantsforseveral otherpoly-aminocarboxylate complexes of TKllI) have also been determined. 

Linder KE (1986) Aminocarboxylate complex of technetium. PhD thesis, Massachusettes Institute... 

Kimura T, Kato Y (1998) Luminescence study on hydration states of lanthanide(III) poly-aminocarboxylate complexes in aqueous solution. J Alloys Compd 275-277 806-810... 

With logK in the range 15-20, [Ln(edta)]2 (ethylenetriaminepentaacetic acid) complexes are quite stable and consequently, the aminocarboxylate complexing unit has been grafted on numerous scaffolds and chromophores to generate stable fluorescent chelates previously described in the literature [29-31] and in patents [32-35]. Ligands based on EDTA scaffold are shown in Fig. 1. 

Poznyak et al. have shown that aminocarboxylate complexes of Co(III) undergo photolysis by UV light to produce products with stable Co—C bonds. The observations can be understood by the reaction sequence in Scheme 7.3. 

The trend is shown in Figine 10 and shows a smooth increase in the exothermic nature of AHny from La to Lu. The Ln +(aq) ions are, of course, simply another class of lanthanide complex and the observed trend in AHny is entirely as expected from the increase in charge density on the ions, which dominates the trend in the stability of aminocarboxylate complexes noted earlier. 

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