Synthesis and Selected Reactivity Studies of a Dissymmetric (Phosphinoylmethylpyridine N‐Oxide) Methylamine Platform

Efficient syntheses for the precursor molecules, 2-{6-[((diphenylphosphoryl)methyl)pyridin-2-yl]methyl}isoindoline-1,3-dione (2), 2-[(1,3-dioxoisoindolin-2-yl)methyl]-6-[(diphenylphosphoryl)methyl]pyridine 1-oxide (3), and their 6-[bis(2-(trifluoromethyl)phenyl)phosphoryl]methyl analogues are reported along with their transformations into the dissymmetric ligands, [(6-(aminomethyl)pyridin-2-yl)methyl]diphenylphosphine oxide (4), 2-(aminomethyl)-6-[(diphenylphosphoryl)methyl]pyridine 1-oxide (5) and 2-(aminomethyl)-6-{[bis(2-(trifluoromethyl)phenyl)phosphoryl]methyl}pyridine 1-oxide (5-F). Selected reactivity of the aminomethyl substituent of 4 and 5, as well as complexation reactions of several of the compounds with lanthanide(III) ions are described. Molecular structures of three uniquely different complexes, {Pr{2-[HC(O)N(H)CH2]-6-[Ph2P(O)CH2]C5H3NO}(NO3)(3)(MeOH)}(2), {Eu{2-[(Me2N)(2)CN(H+)CH2]-6-[Ph2P(O)CH2]C5H3N(H)(+)}(NO3)(4)(OMe)} and {Er{2-[(C8H4O2)NCH2]-6-[Ph2P(O)CH2]C5H3N(O)}(NO3)(3)(MeOH)}(CH3)(2)CO, have been determined by single-crystal X-ray diffraction methods. The observed and computationally modeled structures that employ bidentate and tridentate ligand/metal interactions are compared. These results suggest further ligand modifications that should provide improved solvent extraction reagents.