Dicarboxylate ligands

The simplest dicarboxylate ligand is oxalate, 020 . Thorium oxalate complexes have been used to produce high density fuel pellets, which improve nuclear fuel processes (73). The stabiUty of oxalate complexes and the relevance to waste disposal have also been studied (74). Many thorium oxalate complexes are known, ranging from the simple Th(C20 2 >5rl2 complex salts such as where n = 4, 5, or 6 and where the counterions... 

Figure 4.1 clearly illustrates the modular construction of MOFs, with ligands used as pillars and metal clusters as node points. One unique feature of MOFs seems to be the possibihty to systematically modify their lattice. For instance, by replacing the terephthalate ligands of MOF-5 (Figure 4.1) with different dicarboxylate ligands, a family of isoreticular metal-organic frameworks (known in literature as the... 

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.)...

Stability constants for calcium complexes of a selection of hydroxycarboxylate ligands are listed in Table VII (239,246,272-274). For tartrate, malate, and citrate stabilities decrease in the expected order Ca2+> Ba2+> Ra2+ (231,275). The stability constant for the complex of pyruvate (logiOifi 0.8 (273)) is similar to that for acetate calcium complexes of a-ketoglutarate and of oxaloacetate are somewhat more stable (logio-Ki = 1.3, 1.6 respectively (273)). The sequence logio-Ki = 3.0, 1.4, 1.1, 0.6 for the dicarboxylate ligands oxalate, malonate, succinate,... 

Using a sterically crowded dicarboxylate ligand XDK, Tanase and Lippard have reported a dinuclear complex [Mn20(XDK)(4,4 -Me2bpy)2(N03)2] (100). 

Yun et al. have reported a carboxylate- and a phosphodiester-bridged dinuclear magnesium(II) complex with dicarboxylate ligand 52 (56). The reaction of 52 with 2 equivalents of Mg(N03)2 in MeOH gave a carboxylate-bridged complex 53 (see Scheme 12). The Mg-Mg distance... 

It is a matter of some concern that we do not know which ligands Y will generate effective axial symmetry in Ln(III)Y in the last part of the series while it would appear to be obtained almost invariably for Pr(III). Dobson, Delepine and Menear29) in a careful study of the complexes of a dicarboxylate ligand which has a rigid frame showed that the Ln(III) ions of the second part of the series do not give axial complexes. They come to no firm, final, conclusions as to why this is. Now it is not just the physical structural properties which are of interest. Very similar problems have arisen in the discussion of stability constants and rates of reaction of Ln(III) ions. 

Furthermore, RAPTA-C derivatives in which the chlorides have been replaced by chelating dicarboxylate ligands that resist hydrolysis display very similar in vitro activity to RAPTA-C [23]. Interestingly, RAPTA-C and carboplatin induce similar effects on DNA and yet their in vivo activities are markedly different [24]. This disparity may be attributed to targets other than DNA being relevant to provide their therapeutic effect. 

When a dicarboxylate ligand bridges two tin centers (Figure 2.4.1(b)) ... 

Bu2)2Sn(2,5-PDC) 3] (2,5-PDC = 2,5-pyridinedicarboxylate, D = Lewis base, such as DMSO, H2O) and [ (n-Bu2)2Sn(l,3-BDC)(D) 3] (1,3-BDC = 1,3-benzenedicarboxylate) (Table 2.4.2, entries 4 and 6) deserve special mention. Both of these are macrocyclic compounds formed as a result of intermolecular bridging by the dicarboxylate ligands. Among these, [ (n-Bu2)2Sn(2,5-PDC) 3] forms a three-dimensional hybrid supramolecular network which traps hydrophobic molecules in its microporous channels. ... 

The IR spectra of (Ph3SnCl)4[p4- Y(C02)2 ], where Y = CH2, CH2CH2 or (Z)-CH=CH, are consistent with tetradentate dicarboxylate ligands.384 The IR spectrum of [dibenzyl(2-furanylcarboxylato)tin(IV)]oxide shows the presence of bridging carboxylates.385... 

To approach the design of a dicarboxylate ligand that would effectively bridge the Rh-Rh core, we first optimized the parent Rh2(CF3C02)4 using ZINDO... 

Gd(Tp)2 2 l94-(02C)2C6H4 ] (Fig. 2.152), structurally characterized, contains two gadolinium centers linked by a ditopic 1,4-benzene-dicarboxylate ligand.630... 

FIGURE 4.26 Proposed mechanism for oxygenation of diiron(II) complexes with dinucleat-ing dicarboxylate ligands.92... 

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