Synthesis and Coordination Chemistry of 2,6-Bis(diphenylphosphinomethyl)phenol P,P‘-Dioxides

The 2,6-bis(diphenylphosphinomethyl)phenol-P,P‘-dioxides, [Ph₂P(O)CH₂]₂C₆H₂(R)OH, with R = H (2a), Br (2b), Me (2c), ^tBu (2d), were prepared via Arbusov reactions between Ph₂POEt and the phenol derivatives (ClCH₂)₂C₆H₂(R)OH. The compounds have been characterized by spectroscopic methods, and their coordination chemistry with lanthanide nitrates, Ln(NO₃)₃, has been surveyed. The 1:1 complexes [Er(2c)(NO₃)₃]·Me₂CO and [Nd(2d)(NO₃)₃·Me₂CO]·Me₂CO have been structurally characterized by single-crystal X-ray diffraction methods, and the ligands found to act as neutral tridentate chelates. No evidence was found for the formation of 2:1 L:M complexes suggesting that these derivatives of 2 are weaker chelators than the related 2,6-bis(diphenylphosphinomethyl)pyridine N,P,P‘-trioxide chelates.