Modular Synthesis of Monoanionic PN Ligands Leads to Unexpected Structural Diversity in Lanthanum Chemistry.

We report a new synthetic entry to a series of -substituted anilidophosphine ligands (short HPN, R = pTol (), 3,5-dimethylphenyl (), 3,5-bis(trifluoromethyl)phenyl (), 2-methoxyphenyl (), diisopropylphenyl (), and adamantyl ()), allowing a detailed tuning of their steric (and electronic) properties. could be converted into their lithium salts , which are effective precursors for salt metathesis reactions. The new ligands are used for the synthesis of an array of lanthanide complexes using LaCl(THF) as a precursor. Depending on the steric bulk of the anilidophosphine ligand, either chloride-bridged dimers of the general formula [(PN)La(μ-Cl)La(PN)] (R = pTol (), 3,5-dimethylphenyl () and adamantyl ()) or mononuclear complexes of the general formula (PN)LaCl (R = diisopropylphenyl ()) are observed, if the complexation reaction is carried out in toluene. Contrary, if salt metathesis reactions are carried out in dimethoxyethane (DME) as a coordinating solvent, complexes of the general formula [(PN)La(μ-Cl)Li(DME)] (R = Adamantyl () and R = 2-methoxyphenyl ()) or [Li(DME)][(PN)LaCl] (R = 3,5-bis(trifluoromethyl)phenyl (), R = pTol () and R = 3,5-dimethylphenyl ()) are observed. All ligands and complexes have been thoroughly characterized by 1D and 2D NMR spectroscopy, IR, and X-ray crystallography. Finally, the steric demand of the new anilidophosphine ligands is evaluated using SambVca simulations.