Schiff base metal complexes

Recent aspects of the stereochemistry of Schiff-base metal complexes. S. Yamada, Coord. Chem. Rev., 1966,1, 415-437 (65). 

Coordination Geometries of Schiff-Base Metal Complexes. 9... 

Of importance, these Schiff base metal complexes that contain cis coordination sites allow binding of a substrate (monomer) and the growing polymer chain or can capture a bidentate substrate (growing carbonate polymer chain). Indeed, the use of... 

As alluded to earlier, an important advancement in catalyst design for the copolymerization of epoxides and carbon dioxide involves the use of Schiff base metal complexes where the ligand is in a cis configuration, as depicted in Fig. 9. For example, Chen and coworkers have recently reported a (salen)Co... 

Table 8 Polymerization of d,L-lactide with various amino acid Schiff base-metal complexes...

A group at the Academy of Sciences in Moscow 197) has synthesized chiral threonine. Derivatives of cyclic imino acids form copper complexes with glacine and carbonyl compounds. Hydroxyethylation with acetaldehyde and decomposition of the resulting complexes produced threonine with an optical purity of up to 97-100% and with threo/allo ratios of up to 19 1 197). The chiral reagents could be recovered and re-used without loss of stereoselectivity. The mechanism of this asymmetric synthesis of amino acids via glacine Schiff base/metal complexes was also discussed 197). 

Schiff base metal complexes have been shown to act as ligands.393,394 When the calculated quantity of silver perchlorate in ethanolic solution was added to a chloroform solution of... 

Despite the considerable number of papers which have appeared on the structure of Schiff base metal complexes, a relatively small number of free ligands have been structurally characterized. In addition, only two SALAN derivatives are reported in the reviews collecting structure determinations published up to 1965.9 Therefore, no previous review on structural properties of free Schiff bases has been so far reported. Thus, these aspects will be fully described in the next subsections. However, it may be useful to report here the values quoted in ref. 9 of average C—N bond lengths for single, partial double and triple bonds (Table 2). 

Benzyl complexes metal hydroxides chemistry, 358 a-monooxime, 272 Benzylideneimine Schiff bases metal complexes, 721 Beryllium, alkylalkoxy synthesis, 340 ... 

The formation of imine or Schiff base metal complexes can be effected very readily by arranging for reaction of the amine with the carbonyl compound to take place in the presence of the metal ion. Nucleophilic attack of the amine on the carbonyl group is enhanced by polarization of the carbonyl group by coordination of the oxygen atom to the metal ion. Furthermore, the reaction is reversible unless steps are taken to effect dehydration of the intermediate hydroxy amine, and coordination of the product imine is an important factor in the promotion of the reaction by suitable metal ions. 

A kinetic study of the hydrolysis of JV-salicylideneaniline (113) in the presence and absence of cobalt(II), nickel(II), copper(II) and zinc(II), using 10% ethanol-water as solvent, has been carried out by Dash and Nanda. The (1 1) Schiff base-metal complexes (ML ) were found to undergo acid-catalyzed hydrolysis at rates decreasing with the thermodynamic stabilities of the complexes, the most thermodynamically stable complexes undergoing the slowest rate of hydrolysis. More recent measurements using high copper(II) to ligand ratios have indicated that the copper(II)-imine is quite stable to hydrolysis at pH 5. 

Figure 1.27 A donor-acceptor Schiff base metal complex...

Sinn, E., and C. M. Harris, Coordination, Chem. Rev., 1969, 4, 391 (Schiff base-metal complexes as ligands). 

Schiff bases and their complexes with Cu ", Zn ", Ni and Sn " as potential antitumor agents, were used in the fluorimetric method for preliminary screening of antitumor agents (Lee etal. 1993). The method was based on the consistency of the in-vivo and in-vitro interactions of drugs with DNA. Studies of Schiff bases-metal complex interaction with DNA using a fluorescence probe [ethidium bromide (EthBr)-DNA system] identified the parallelism between binding constants and antineoplastic... 

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