Terphenylthiolate-Ligated Lanthanide Terminal Methyl Complexes Form Crystallographically Characterizable Terminal...

The sterically bulky terphenylthiolate ligand {S[C₆H₃-2,6-(C₆H₂-2,4,6-Pr₃)₂]}^1-, (SAr)^1-, has permitted the isolation of the terminal methyl complexes Ln(SAr)₂CH₃, 1-Ln, Ln = La and Nd, from salt metathesis between Ln(SAr)₂I and methyllithium. These complexes react with carbon monoxide to afford the first structurally authenticated examples of terminal acyl complexes of the rare-earth elements, Ln(SAr)₂(η²-OCCH₃), 2-Ln. However, in the presence of lithium iodide, the reaction between Ln(SAr)₂CH₃ and CO forms the unique trimethylcyclopropanetriolate trianion, [cyclo-(OCCH₃)₃]^3-, in the complex [Ln(SAr)(μ-I)(μ-OCCH₃)]₃, 3-Ln. This CO insertion product arises from the formation of six C-C bonds, demonstrating the power of the (SAr)^1- ligand to generate new organometallic rare-earth metal reaction chemistry with CO.