Synthesis of the water-soluble [Rh(Tpms)(CO)(PTA)] compound, the first transition metal complex bearing the 1,3,5-triaza-7-phosphaadamantane (PTA) and the tris(1-pyrazolyl)methanesulfonate (Tpms) ligands

Abstract

The water-soluble Rh I compound [Rh(Tpms)(CO)(PTA)] ( 1) (Tpms = O 3SC(pz) 3 −, PTA = 1,3,5-triaza-7-phosphaadamantane) has been easily prepared in high yield by a single-pot reaction of [{Rh(CO) 2(μ-Cl)} 2] with PTA and the tris(1-pyrazolyl)methanesulfonate lithium salt Li(Tpms), in a CH 2Cl 2/MeOH solution at room temperature. This synthetic strategy can be easily applied to the preparation of general [Rh(Tpms)(CO)(L)] (L = phosphine) complexes and constitutes a substantial improvement over the previously described procedures. Compound 1 is air stable in the solid state and water-soluble, affording stable solutions under an inert atmosphere. It has been characterized by IR, 1H, 31P{ 1H} and 13C{ 1H} NMR spectroscopies, elemental and single crystal X-ray diffraction structural analyses. The solid state structure of 1 has a square-planar geometry with the Tpms ligand coordinating the metal centre in a (κ 2: N, N) bipodal mode. The title compound has also been investigated by cyclic voltammetry in CH 3CN, and values of the E L Lever and P L Pickett electrochemical parameters (which measure the ligand net electron-donor character) are proposed for the PTA ligand. Complex 1 represents the first example of a transition metal complex bearing both PTA and Tpms (or any other tris(1-pyrazolyl)methane or derivative) ligands.