Lanthanoid ions reduction

Regioselective 1,2-reduction of enones to the corresponding allylic alcohols is achieved with NaBH4 in the presence of lanthanoid ions, such as La +, Ce ", Sm + Eu ", Yb + and This procedure is... 

Chiral recognition of A-[Co(phen)3]3+ has been observed in a modified /3-cyclodextrin.772 Chiral discrimination has also been seen in photoinduced energy transfer from luminescent chiral lanthanoid complexes773 to [Co(phen)3]3+ and between photoexcited [Ru(bpy)3]2+ and [Co(phen)3]3+ co-adsorbed on smectite clays.774 The [Co(bpy)3]3+ ion has been incorporated into clays to generate ordered assemblies and also functional catalysts. When adsorbed onto hectorite, [Co(bpy)3]3+ catalyzes the reduction of nitrobenzene to aniline.775 The ability of [Co(phen)3]3+ to bind to DNA has been intensively studied, and discussion of this feature is deferred until Section 6.1.3.1.4. 

Table 25.4 Standard enthalpies of atomization and hydration (at 298 K) of the Ln ions, sums of the first three ionization energies of Ln(g), and standard reduction potentials for the lanthanoid metal ions.

Besides the ubiquitous oxidation state Ln +, the higher oxidation state Ln" + is also encountered with some lanthanoids, for example, in the case of the ions Ce" + (f°, orange-yellow), Pr + (f, colorless), Nd" + (f, blue-violet), Tb + (f , colorless), and Dy + (f , orange-yellow) (Table 1). However, all three states Ln + + " + are never encountered for the same element. Thus, the highly important mechanistic steps of oxidative addition and reductive elimination typical for the d-block metals cannot occur with the f-block metals as they would involve M + or transformations, respectively. ... 

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