Ligands carboxyl groups

EthylenediaminetetraaceticAcid. Ethylenediaminetetraacetic acid (EDTAH has six potential donor groups two nitrogen atoms and four carboxylate groups. If EDTA 4— acts as a hexadentate ligand to a metal, the resulting complex contains five five-membered chelate rings and has a charge that is four less than that of the metal ion. 

A hydroxyl group is situated ortho to a carboxyl group which as a bidentate ligand is terminally metallized on the fiber when aftertreated with dichromate. An example is Alizarine Yellow GG [584-42-9] (50) (Cl Mordant Yellow 1 Cl 14025). Cr(III) has a coordination number of six, and therefore normally two dye molecules of the sahcyhc type are chelated to the metal ion. 

The methanol can be removed by heating gently in vacuo. Similar compounds can be made with other carboxylate groups, either by using this method or by heating the acetate with excess carboxylic acid. Treatment of the anhydrous carboxylate with various neutral ligands (L) or anionic donors (X-) forms Rh2(OCOR)4L2 and [Rh2(OCOR)4X2]2-, respectively. The colour of the adduct depends on the donor atom in L (or X) ... 

There is a slight dependence on the nature of the carboxylate group and upon the axial ligand, but they are not imposed by the steric requirements of the carboxylates. Some points are germane to this ... 

The platinum(IV) compound that has shown most promise is carboplatin (paraplatin), which received FDA approval in 1990. Features to note in its structure are the use of hydroxy and carboxylate groups to improve water solubility. As noted above, the ammine ligand has been found to need at least one hydrogen, possibly for hydrogen-bonding to phosphate groups in the DNA (Figure 3.116). 

Figure 4.5 A MOF oxidation catalyst based on Cu paddlewheels connected by 1,4-trans-cyclohexane-dicarboxylate ligands (only carboxylate groups are explicitly shown). After oxidation by H2O2, paddlewheels are linked by peroxo bridges (Cu = blue O = red C = gray) [34], (Reproduced by permission of the Royal Society of Chemistry.)...

There are many ligands and group-specific reagents that have been demonstrated to alter the properties of H,K-ATPase, and which are not clinically useful. For example, there is a variety of chemicals that have been used in studies on structure-function relations of H,K-ATPase and that inhibit the enzyme in vitro by modification of its amino [49,67,158], sulfhydryl [95,165,166] or carboxyl groups [140]. 

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