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Abstract: The preferential substitution of oxo ligands over alkyl ones of rare‐earth complexes is commonly considered as “impossible” due to the high oxophilicity of metal centers. Now, it has been shown that simply assembling mixed methyl/oxo rare‐earth complexes to a rigid trinuclear cluster framework cannot only enhance the activity of the Ln‐oxo bond, but also protect the highly reactive Ln‐alkyl bond, thus providing a previously unrecognized opportunity to selectively manipulate the oxo ligand in the presence of numerous reactive functionalities. Such trimetallic cluster has proved to be a suitable platform for developing the unprecedented non‐redox rare‐earth‐mediated oxygen atom transfer from ketones to CS2 and PhNCS. Controlled experiments and computational studies shed light on the driving force for these reactions, emphasizing the importance of the sterical accessibility and multimetallic effect of the cluster framework in promoting reversal of reactivity of rare‐earth oxo complexes. [ABSTRACT FROM AUTHOR]

Cluster models of SiO2-200 are proposed and compared with spectroscopic (IR and NMR) experimental data. Five models describing the variety of surface silanols (isolated, vicinal and germinal) at the SiO2-200 surface have then been derived and used to study the grafting reaction of homoleptic silylamide lanthanum(iii) complexes. Three different grafting modes have been obtained (mono-, bi- and tri-grafted) in line with the experimental knowledge. In terms of energetic stability as well as spectroscopic properties of coordinated OPPh3 (as a probe), all modes could coexist at the surface. The analysis of the δ(31P) chemical shifts for the coordinated OPPh3 indicates some possible important differences in Lewis acidity of the lanthanide centre, which may impact the catalysis. [ABSTRACT FROM AUTHOR]

The reactivity of rare-earth complexes RE(BH4)2(C3H5)(THF)x (RE = La, Nd, Sm, Y, Sc) toward the Ring-Opening Polymerization (ROP) of ε-caprolactone (ε-CL) was rationalized by Density Functional Theory (DFT) calculations. Even if the polymerization reaction can be initiated by both RE-(BH4) and RE-allyl bonds, experimental investigations have shown that the initiation via the borohydride ligand was favored, as no allyl group could be detected at the chain-end of the resulting polymers. DFT studies could confirm these observations, as it was highlighted that even if the activation barriers are both accessible, the allyl group is not active for the ROP of ε-CL due to the formation of a highly stable intermediate that disfavors the subsequent ring-opening. [ABSTRACT FROM AUTHOR]

Introduction of four tBu groups into a carbazol-ylframework leads to switching of the metal–ligand bonding inthe Ln(II) and Ca complexes from σ to π. Complexes [(tBu4Carb)2Ln] (Ln = Sm, Eu, Yb, Ca)are amido analogues of metallocenes, which adopt the sandwich structureswith parallel disposition of the aromatic ligands and strong contributionof η3-mode into η5metal–ligandbonding. The DFT calculations demonstratedthat the geometry is due to steric effects (presence of the bulky tBu groups) as well as the maximization of the overlap betweenthe Sm 4f orbital and the π-type nitrogen lone pairof the carbazol-yl ligand. Coordination of DME to the metal centersin [(tBu4Carb)2M] (M = Sm,Yb) results in the heterolytic dissociation of the metal–ligandπ-bond and the formation of ionic complexes [tBu4Carb–]2[Ln2+(DME)n]. [ABSTRACT FROM AUTHOR]