Reactions without metal-ligand bond

Substitution reactions without metal-ligand bond cleavage... 

The first example of a reaction in which a metal acetylacetonate ring was substituted without metal-ligand bond rupture was reported in 1925 (171). The treatment of tris(2,4-pentanediono)chromium(III) with bromine in chloroform gave the tribromo compound ... 

A variety of other reactions occur without metal-ligand bond cleavage. Reactions of this type have been used to convert nitrogen-containing ligands... 

NaOH], 0.045 for cis- trans isomerization at 405 nm. The thermal and photochemical reactions proceed by different mechanisms an S nI mechanism is favoured for the thermal reactions and the photochemical reactions are believed to proceed by a twist mechanism and without metal-ligand bond cleavage. ... 

D. Reactions without Metal-Ligand Atom Bond Cleavage... 

A few studies have appeared dealing with the formation of cobalt(in) complexes without the cleavage of metal-ligand bonds. These reactions often involve nucleo-... 

The anation reaction of a cobalt(III) ammine aquo complex using (N02 ) as an anionic ligand also occurs without the cleavage of metal-ligand bond. 

One approach to achieving more stable metal-ligand bonds is to employ multidentate ligands. Multiple bound ligands are particularly desirable for catalytic applications because they can liberate coordination sites on the metal without complete dissociation. The common degradation of a catalyst over time is very often a result of dissociation or side reactions of the supporting ligand. The stability of REM complexes particularly benefits from the combination of... 

This reaction is a principal method of forming IIIB-transition-metal cr bonds. The formation of thermodynamically favored alkali-metal halides or related salts and acids HX enhances the easy formation of those bonds. A second possible interaction between anionic metal bases and group-IIIB halides is a simple acid-base relationship without elimination of halide anions. However examples of this are rare, and they have been described often for group-IIIB compounds without halogen ligands ( 6.5.3.2). 

Herberhold reported activation of water with Re2(CO)io. The reaction proceeded at 200°C to give a tetranuclear complex [Re(CO)3( X -OH)]4 (23) in quantitative yield, and evolution of dihydrogen and CO was observed (Eq. 6.13) [21]. Complex 23 has a pseudo-cubane structure without metal-metal bonds in which the Re(CO)3 groups are linked by triply-bridging OH ligands. Also in this case, no presumed intermediate hydrido(hydroxo) species was detected. 

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