Synthesis and properties of tris(2,4,6-trimethoxyphenyl)phosphine and tris(2,4,6-trimethoxyphenyl)phosphine oxide

Abstract

The functionalized triaryl phosphine tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) was prepared and characterized by single crystal X-ray diffraction studies and multinuclear NMR spectroscopy. The asymmetric unit contains two independent molecules of TMPP on general positions that adopt a pseudo-propeller arrangement of the arene substituents. The basicity of TMPP was evaluated by measuring the ν A1(CO) stretching mode for the complex Ni(CO) 3L; the value for Ni(CO) 3TMPP is ν A1(CO) = 2048 cm −1, which is the lowest reported value for a tertiary phosphine complex (PR 3)Ni(CO) 3. The phosphine oxide derivative, tris(2,4,6-trimethoxyphenyl)phosphine (TMPPO), was prepared by oxidation with H 2O in refluxing acetone. In the structure of TMPPO, the oxygen atom of the phosphine oxide is hydrogen bonded to two interstitial water molecules. Both the phosphine and phosphine oxide compounds were fully characterized by a variety of physical and spectroscopic techniques, including NMR ( 1H, 31P, 13C), IR and electronic absorption spectroscopies and cyclic voltammetry.