Silver complexes carboxylates

Limited structural information is available for silver(I) carboxylates, despite their extensive use as catalysts in the manufacture of urethane polymers. This is in part due to their frequent insoluble and light-sensitive nature making chemical characterization of the complexes difficult. Dimeric structures have been reported for the perfluorobutyrate249 and trifluoroacetate complexes.250 In each case two-fold symmetry was crystallographically imposed. The Ag—O bond lengths were 223-224 pm, and in the more accurate determination of the trifluoroacetate, the Ag—Ag separation was found to be 297 pm. A dimeric structure was also found for the silver(I) complex of 3-hydroxy-4-phenyl-2,2,3-trimethylhexane carboxylate.251 In the asymmetric crystal unit the Ag---Ag separations were 277.8 and 283.4 pm. 

Recently the use of mixed lanthanide silver complexes as NMR shift reagents has been assessed. In the original experiments232,233 silver(I) carboxylates such as Ag02CCF3 and Ag02CC3F7 were used, although later studies showed that larger shifts could be induced with silver /3-diketonates (see Section 54.1.4.4). 

Table 49.357 It was assumed that in all of these cases bonding was primarily through the Group VI donor atom with minimal chelation through the carboxyl groups. This was supported by the apparent absence of a silver complex for X = CH2.

Silver carboxylate compounds are fight-sensitive and generally insoluble in most solvents, making it difficult for their structural characterization. In contrast, the zwitteri-onic betaine ligands R3N+(CH2) C02 form stable silver complexes that are soluble in water and ethanol, and a variety of discrete dimers or polymeric chain/network stractures constracted by the linkage of dimeric subunits have been obtained. ... 

Macrocyclic Thiophens. - Novel macrocyclic Schiff-bases (161), containing thiophen, have been prepared by the non-template condensation of a,co-amino-ethers with thiophen-2,5-dicarbaldehyde. Silver complexes were prepared and crystal structures were determined both for some macrocycles and for a silver complex. In attempts to prepare bridged thia[17]-annulenes, (162) was prepared through the reaction of 2,5-dichloromethyl-thiophen with p-carboxytoluene-a-thiol. Transformation of the carboxyl groups of (162) into bromomethyl, followed by reaction with sodium sulphide,gave (163). The Wittig reaction of 3,4-diformyl-2,5-dimethylthiophen... 

Paramonov and coworkers synthesized silver(I) carboxylate complexes by the reaction of silver(I) carboxylate with the neutral ligand in absolute ether or ethanol. By thermal analysis and XRD, the relations between volatility and crystal structures of the complexes were discussed [214]. 

Other work involving complexation of ferrocenylphosphines include the preparation of silver complexes of diferrocenylphosphine a trinuclear dirhenium complex dppf as a spacer ligand between rhenium centres dppf in gold complexes palladium and platinum complexes from the carboxylation of [(dppf)MCl2], M = Pd, Pt complexes technetium and rhenium heterometallic complexes mixed silver/nickel complexes ... 

The conversion of primary alcohols and aldehydes into carboxylic acids is generally possible with all strong oxidants. Silver(II) oxide in THF/water is particularly useful as a neutral oxidant (E.J. Corey, 1968 A). The direct conversion of primary alcohols into carboxylic esters is achieved with MnOj in the presence of hydrogen cyanide and alcohols (E.J. Corey, 1968 A,D). The remarkably smooth oxidation of ethers to esters by ruthenium tetroxide has been employed quite often (D.G. Lee, 1973). Dibutyl ether affords butyl butanoate, and tetra-hydrofuran yields butyrolactone almost quantitatively. More complex educts also give acceptable yields (M.E. Wolff, 1963). 

Picolinate and pyridine-2,6-carboxylate give stable complexes, with 4- and 6-coordination. Macrocycles like porphyrins afford silver(II) derivatives most remarkable is the reaction of the macrocycle meso-Me6[14]ane (Figure 4.13). 

Hayama et al.132 discussed the catalytic effects of silver ion-polyacrylic add systems toward the hydrolyses of 2,4-dinitrophenylvinylacetate 84 (DNPVA) by using the weak nudeophilicity of carboxylic groups and the change-transfer interactions between olefinie esters and silver ions133Metal complexes of basic polyelectrolytes are also stimulating as esterase models. Hatano etal. 34, 13S) reported that some copper(II)-poly-L-lysine complexes were active for the hydrolyses of amino acid esters, such as D- and L-phenylalanine methyl ester 85 (PAM). They... 

When Br2 reacts with aryl R, at low temperature in inert solvents, it is possible to isolate a complex containing both Br2 and the silver carboxylate see Bryce-Smith, D. Isaacs, N.S. Tumi, S.O. Chem. Lett., 1984, 1471. 

Silver(I) complexes with oxygen donor ligands have been prepared with three different types of ligands /3-diketonates, carboxylates, and crown ethers. 

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