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The grafting of a lanthanum trisbenzyl derivative onto dehydroxylated silica affords a mixture of [(≡SiO)2La(CH2Ph)(THF)n] and [(≡SiO)La(CH2Ph)2(THF)m] surface sites, in respective proportions of 80 and 20%, as evidenced from mass balance analyses, IR and ¹H, 13C and 29Si 1D and 2D solid-state NMR spectroscopy. Significant transfer of alkyl groups from lanthanum to the surface was demonstrated. The grafting mechanism was also probed by DFT calculations, which confirm that benzyl group transfer from the lanthanum to the surface (via Si-O-Si cleavage) occurs readily. This material proved to be active in alkyne dimerization and in ethylene, styrene, and ε-caprolactone homopolymerization. [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]