Aqueous reactions multidentate ligands

Aqueous Reactions of Vanadate with Multidentate Ligands... 

It had been hoped that the reaction of [MoOaCdien)] with oxine, to yield the known compound [Mo02(OH)2(oxine)], would be amenable to kinetic study, to provide rate and mechanism data pertaining to substitution at octahedral molybdenum(vi). Sadly the proposed investigation proved impossible, as [MoOaCdien)] was found to be extensively hydrolysed in aqueous solution. An understanding of multidentate ligand-replacement reactions is helped by knowledge of dissociation mechanisms for these chelates. Recent studies resulting in kinetic or mechanistic information on the dissociation of amino-carb-... 

Stability of the bidentate and multidentate complexes in aqueous solution [16] compared with monodentate complexes. Kinetic studies of gold(III) reactions with ethylenediamine and related ligands show that the initial displacement of one end of the chelate is most often followed by rapid reclosure of the ring, rather than displacement of the second bond to the metal ion [15]. 

Reactions of these ligands have not been studied in aqueous solution. However, their complexes are readily synthesized and are stable but reactive towards heteroligands [41,42], The reported structures all show the vanadium coordinated in monomeric units after the fashion depicted in Scheme 4.9. The multidentate thiolato complexes with tri- or tetradentate functionality are sufficient to satisfy the coordination requirements of the vanadium nucleus. Structurally, the compounds are not much different from analogous complexes formed with oxygen ligands (Section 4.4.2). 

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