Carboxylates dinuclear compounds

Diphenic acid (H2A) also forms diorganotin(IV) complexes, which are with two monodentate -COO groups. On the other hand, soluble dinuclear triorganotin(IV) complexes (where the organo moieties are Me and Ph) contain symmetrically bound carboxylates, while the less-soluble compound (cHexsSn) has two asymmetrically bonded carboxylates. All have Tbp structures with [RsSnirV)] units remote from each other. °... 

The synthesis of lanthanide chemical shift reagents has been the objective of many groups owing to their effect on NMR spectra simplification. A drawback of the commonly used reagents is their sensitivity to water or acids. Tris(tetraphenylimido diphosphinatojpraseodymium [Pr(tpip)3] has been developed as a CSR for the analysis of carboxylic acids.17 Furthermore, it has been found that dinuclear dicarboxylate complexes can be obtained through reactions with ammonium or potassium salts of carboxylic acids, and these compounds can be used to determine the enantiomer composition of carboxylic acids.18... 

Cyclic voltammetry has been also used for estimation of the rate constants for oxidation of water-soluble ferrocenes in the presence of HRP (131). There is a perfect match between the data obtained spectrophotometrically and electrochemically (Table IV), which proves that the cyclic voltammetry reveals information on the oxidation of ferrocenes by Compound II. It is interesting to note that an enzyme similar to HRP, viz. cytochrome c peroxidase, which catalyzes the reduction of H202 to water using two equivalents of ferrocytochrome c (133-136), is ca. 100 times more reactive than HRP (131,137). The second-order rate constant equals 1.4 x 106 M-1 s 1 for HOOCFc at pH 6.5 (131). There is no such rate difference in oxidation of [Fe(CN)e]4- by cytochrome c peroxidase and HRP (8). These comparisons should not however create an impression that the enzymatic oxidation of ferrocenes is always fast. The active-R2 subunit of Escherichia coli ribonucleotide reductase, which has dinuclear nonheme iron center in the active site, oxidizes ferrocene carboxylic acid and other water-soluble ferrocenes with a rate constant of... 

Dinuclear Rh(II) compounds are another class of effective catalysts (227). Electrophilic carbenes formed from diazo ketones and dimeric Rh(II) carboxylates undergo olefin cyclopropanation. Chiral Rh(II) carboxamides also serve as catalysts for enantioselective cyclopropanation (Scheme 95) (228). The catalysts have four bridging amide ligands, and... 

There are a number of dinuclear carboxylate complexes of Co" which show interesting magnetic behavior and contain the [Co2(ft-OH2)(RC02)2]2+ or [Co2(/t-X)(/i-RC02)2]+ core (X = OH, Cl, Br), stabilized by chelating nitrogen ligands to complete the octahedral coordination. The latter can be oxidized to mixed-valence ConCom compounds in which the valences are localized.5... 

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