Modular Synthesis of Monoanionic PN Ligands Leads\nto Unexpected Structural Diversity in Lanthanum Chemistry

We report a new synthetic\nentry to a series of <i>N</i>-substituted anilidophosphine\nligands (short HPN<sup>R</sup>, R =\npTol (<b>HPN</b><sup><b>Tol</b></sup>), 3,5-dimethylphenyl\n(<b>HPN</b><sup><b>3,5Me</b></sup>), 3,5-bis(trifluoromethyl)phenyl\n(<b>HPN</b><sup><b>3,5CF3</b></sup>), 2-methoxyphenyl\n(<b>HPN</b><sup><b>OMe</b></sup>), diisopropylphenyl (<b>HPN</b><sup><b>Dipp</b></sup>), and adamantyl (<b>HPN</b><sup><b>Ad</b></sup>)), allowing a detailed tuning of their\nsteric (and electronic) properties. <b>HPN</b><sup><b>R</b></sup> could be converted into their lithium salts <b>LiPN</b><sup><b>R</b></sup>, which are effective precursors for salt\nmetathesis reactions. The new ligands are used for the synthesis of\nan array of lanthanide complexes using LaCl<sub>3</sub>(THF)<sub>1.2</sub> as a precursor. Depending on the steric bulk of the anilidophosphine\nligand, either chloride-bridged dimers of the general formula [(PN<sup>R</sup>)<sub>2</sub>La(μ-Cl<sub>2</sub>)La(PN<sup>R</sup>)<sub>2</sub>] (R = pTol (<b>3f</b>), 3,5-dimethylphenyl (<b>3d</b>) and adamantyl (<b>3a</b>)) or mononuclear complexes of the\ngeneral formula (PN<sup>R</sup>)<sub>2</sub>LaCl (R = diisopropylphenyl\n(<b>3e</b>)) are observed, if the complexation reaction is carried\nout in toluene. Contrary, if salt metathesis reactions are carried\nout in dimethoxyethane (DME) as a coordinating solvent, <i>–ate</i> complexes of the general formula [(PN<sup>R</sup>)<sub>2</sub>La(μ-Cl<sub>2</sub>)Li(DME)] (R = Adamantyl (<b>4a</b>) and R = 2-methoxyphenyl\n(<b>4d</b>)) or [Li(DME)<sub>3</sub>][(PN<sup>R</sup>)<sub>2</sub>LaCl<sub>2</sub>] (R = 3,5-bis(trifluoromethyl)phenyl (<b>4b</b>), R = pTol (<b>4f</b>) and R = 3,5-dimethylphenyl (<b>4d</b>)) are observed. All ligands and complexes have been thoroughly characterized\nby 1D and 2D NMR spectroscopy, IR, and X-ray crystallography. Finally,\nthe steric demand of the new anilidophosphine ligands is evaluated\nusing SambVca simulations.