Neutral and Cationic Alkyl and Alkynyl Complexes of Lanthanum:  Synthesis, Stability, and Cis-Selective Linear Alkyne Dimerization

Abstract

Neutral triazacyclononane-amide lanthanum dialkyl and dialkynyl complexes were synthesized and structurally characterized. A cationic triazacyclononane-amide lanthanum monoalkyl species was generated and found to be highly active (tof > 100 h-1) in the rare cis-selective catalytic linear dimerization of phenylacetylene.

Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

“…[36,42,54,60,61,65,68,75] For other organic transformations, two instructive examples have recently appeared in the literature. [77,90] Cationic lanthanide alkyl derivatives as homogeneous catalysts appear to be generally superior to their neutral precursors due to their increased electrophilicity towards substrate molecules.…”

Rare earth metal bis(alkyl) complexes bearing amino phosphine ligands: Synthesis and catalytic activity toward ethylene polymerization

“…The C-Ln-C bond angles averaging 111.8°in complexes 4b-e were slightly larger than 103.50(12)°[15b] found in the above mentioned complexes, which were comparable to those of C-Sc-C (113.5(2)°) [15a] and C-Y-C (119.5(2)°) in THF solvated amidinato yttrium bis(alkyl) complex [18], indicating the similar steric environment of the ligands. However, these bond angles were larger than those of C-Ln-C in the rare earth metal bis(alkyl) complexes supported by triazacyclononane (99.41(8)°) [19], triaminoamide (101.96(6)°) [20] and b-diketiminate (108.90(13)°) [21].…”

Regioselective CH Alkylation of Anisoles with Olefins Catalyzed by Cationic Half‐Sandwich Rare Earth Alkyl Complexes

“…Among the most straightforward and atomeconomical routes to anisole derivatives is the C À H alkylation of anisoles with alkenes. To the best of our knowledge, the catalytic ortho-selective CÀH alkylation of anisoles with an alkene has not been previously reported.In view of the strong oxophilicity of rare-earth metal ions [8,9] and the high activity of rare-earth alkyl species toward unsaturated CÀC bonds, [10][11][12] we envisioned that the rareearth alkyl complexes might serve as unique catalysts for the ortho-selective CÀH alkylation of anisoles with alkenes. The Friedel-Crafts reaction of anisoles with alkenes is a well-known route to alkylated anisole derivatives, but such Lewis acid catalyzed alkylation reactions generally suffer from poor regioselectivity and often give a mixture of ortho-and para-regioisomers with the pararegioisomer as the main product, owing to steric and electronic influences.…”

“…In view of the strong oxophilicity of rare-earth metal ions [8,9] and the high activity of rare-earth alkyl species toward unsaturated CÀC bonds, [10][11][12] we envisioned that the rareearth alkyl complexes might serve as unique catalysts for the ortho-selective CÀH alkylation of anisoles with alkenes. Herein, we report the rare-earth catalyzed CÀH bond addition of anisoles to various olefins, which constitutes the first example of catalytic ortho-selective alkylation of an anisole compound with an alkene.…”