Synthesis of Cationic Lanthanide Complexes

Cationic lanthanide complexes are relatively rare because of the large ionic radii and the highly electropositive nature of lanthanide metals, hence it is not easy to distribute the charge efficiently and stabilize the lanthanide cation through a suitable weakly coordinating anion [5, 76]. Several synthetic approaches have been developed and the main methods are summarized in the following sections. 

The lanthanide halides are usually bi(cyclopentadienyl) and related lanthanide complexes M is an alkali metal or silver, and A is an anionic transition metal carbonyl compound or tetraphenyl borate. The formation of the insoluble salt MX is a driving force for this reaction. 

The classical divalent organolanthanide complexes, mainly for Sm + and Yb +, have strong reducing potentials. They can reduce a series of transition metal carbonyls and AgBPh4 to give the cationic lanthanide complexes. 

Cationic lanthanide complexes have been found to be efficient catalysts for various organic transformations and polymerizations. The details are given in Section 8.6. 

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