Double ligand transfer

Scheme 19 First preparation of a [Cp99mTc(CO)3] labelled biomolecule by the so-called double ligand transfer approach...

CpX)Re(CO)3 where X is an acyl group (-COR) in which R carries the biomolecules of interest to target the Re(CO)3 fragment to the required biological site. The so-called double-ligand-transfer reactions also provide a mild synthesis of (CpX)Re(CO)3 derivatized with biomolecules. ... 

Fig. 2.3.8. Preparation of " Tc(CO)3 cyclopentadienyl (cp) carboxylate derivative illustrating the double-ligand transfer approach (Saidi 2001 Wenzel 1994)...

These products can be formed by a ligand transfer from an intermediate in which the double bond is associated with the Pb. 

In the oxidation of bromide by thallic ions a double electron transfer from the central atom to two separate ligands was postulated 27)... 

The same results may be interpreted by a double electron transfer to a single ligand, which seems more plausible from the kinetic standpoint... 

Another copper-induced reaction which may be reinterpreted in view of our mechanism is the copper-induced chlorination of ketones (64). It seems reasonable to suggest that Cu(II) bound to the ketone is oxidized to Cu(III) by C11CI2, which, in the given medium, is less stable than Cu(I). Subsequently, Cu(III) oxidizes its chlorine ligand in a double electron transfer to C1+, followed by the latter s addition to the enolic double bond. 

Acyclic tricarbonyl(diene)iron complexes may be prepared by reaction of a 1,3-diene with (1), (2), or (3) either thermally, photochemically, or under the influence of ultrasonic stirring (Scheme 62). Ligand transfer species, such as (benzylideneacetone)Fe(CO)3, (l-aza-1,3-diene)Fe(CO)3, or bis( -cyclooctene)Fe(CO)3 are also useful for the complexation of dienes nnder mUd reaction conditions. The thermal reaction of nnconjugated dienes with (1) generally results in double bond migration... 

Figure 3.8. An example of a double-ligand or outer-sphere redox process. An electron is transferred from the reductant to the oxidant metal over two ligand anions, CN and Cl. The rate constant is 4 X 10- M- s" ...

Os and Re complexes 32-35 (Chart 5.7) are systems in which the metal centers are attached in a pendant fashion to a bipyridine-containing conjugated oligomer [45]. In the case of the mixed Ru-Os complex 33, energy transfer from Ru to Os is efficient and results in Os-based emission. The authors ascribed this to a Dexter-type double-electron transfer , mediated by the conjugated ligand. 

Fig. 5.7 Schematic representation of the 2/t, 2p, 2/t-lp and h-2p determintmts. DLMCT = double ligand-to-metal charge transfer, DMLCT = double metal-to-hgand charge transfer...

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