The 6-amino-6-methyl-1,4-diazepine group as an ancillary ligand framework for neutral and cationic scandium and yttrium alkyls.

The 6-amino-6-methyl-1,4-diazepine framework is a readily available neutral 6-electron ligand moiety, suitable to support cationic group 3 metal alkyl catalysts; it also provides convenient access to tri- and tetradentate monoanionic ligand derivatives.

Neutral versus cationic Group 3 metal alkyl catalysts: performance in intramolecular hydroamination/cyclisation.

The relative catalytic activity of neutral dialkyl versus cationic monoalkyl Group 3 metal catalysts in the intramolecular hydroamination/cyclisation of the 2,2-dimethyl-4-pentenylamine reference substrate was investigated. This was found to depend strongly on the nature of the monoanionic ancillary ligand. With a bidentate amidinate ligand, the neutral catalysts were quite effective, but their cationic derivatives showed a much lower activity.

One ligand fits all: cationic mono(amidinate) alkyl catalysts over the full size range of the group 3 and lanthanide metals.

Using a sterically demanding amidinate ancillary ligand and an in situ alkylation procedure, neutral mono(amidinate) dialkyl and cationic mono(amidinate) monoalkyl complexes were prepared for metals spanning the full size range of the group 3 and lanthanide metals. The activity of the cationic monoalkyls in catalytic ethene polymerization was found to vary by over 2 orders of magnitude depending on the metal ionic radius, the intermediate metal sizes being found to be the most effective.

Yttrium alkyl complexes with a sterically demanding benzamidinate ligand: synthesis, structure and catalytic ethene polymerisation.

The benzamidinate yttrium dialkyl complexes [PhC(NAr)2]Y(CH2SiMe3)2(THF)n (Ar = 2,6-diisopropylphenyl; n = 1, 2) were prepared; when activated with [PhNMe2H][B(C6F5)4], the species with n = 1 polymerises ethene to polyethene with a narrow polydispersity.

Synthesis and Properties of Lanthanum- Pyrene Complexes-Structure of [(Cp*La) (μ-Cl) (thf)(μ-η :η :η -C H )], the First Complex with a Pyrene Trianion.

Different bonding modes are characteristic for the lanthanum centers of the title compound, a trinuclear lanthanum-pyrene complex in which an arene trianion is present for the first time (see picture for the structure). Thus, La1 and La3 reside in a tetrahedral environment, the La2 center in a distorted trigonal-bipyramidal one.