Lanthanide amidinates

The use of dicarbodiimides as monomers in polyaddition reactions have not as yet found wide utility. However, polymers containing carbodiimide groups are known, and further nucleophilic reactions of these polymers with numerous substrates are reported. Carbodiimides, generated in situ from isocyanates are used as catalyst in the formation of polyamides from diisocyanates and dicarboxylic acids. Also, homoleptic lanthanide amidinates, made from carbodiimides, exhibit high catalytic activity for the ring opening polymerization of e-caprolactone at room temperature. ... 

The lithium amidinates are used as precursors for homoleptic lanthanide amidinates. Lanthanide amidinate complexes have a high catalytic activity in the polymerization of ethylene. They are also used in the manufacture of membranes. Lanthanide amidinate complexes 37 (La=Er, Y, Gd) are also obtained from alkyl metal complexes 36 and... 

The proposed mechanism for the addition of terminal alkynes and amines to carbodiimides is shown in Figure 8.40. The organolanthanide alkynyl or amide formed in situ is the active intermediate, and the key step is the hydrolysis of a lanthanide amidinate or guanidinate species. 

Homogeneous Catalysis Using Lanthanide Amidinates and Guanidinates... 

Olefin Polymerization Reactions Catalyzed by Lanthanide Amidinates... 

At the time when the first lanthanide amidinate were reported in the early 1990s, these compounds appeared to be just laboratory curiosities for which nobody could envisage any practical uses. This situation changed completely when in 2002 it was discovered that homoleptic lanthanide tris(amidinate) complexes show extremely... 

Homogeneous Catalysis Using Lanthanide Amidinates and Guanidinates 4.2.2 ROP of Cyclic Esters... 

The ROP of TMC using the homoleptic lanthanide amidinate complexes [RC(NCy)2]3Ln (R = Me, Ph Ln = La, Nd, Sm, Yb) as single-component initiators was investigated in detail. It was found that the substituents on the amidinate ligands and the metal centers had a great effect on the catalytic activities of these complexes, that is, Me > Ph, and La > Nd > Sm > Yb. Thus, the lanthanum acetamidinate [MeC(NCy)2]3La showed the highest catalytic activity [64]. 

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