New aryl phosphinite ligands avoiding <i>ortho</i>-metallation: Synthesis and molecular structures of <i>trans</i>-[PdCl2(PPh2OR)2] and <i>trans</i>-[Rh(CO)Cl(PPh₂OR) ₂] (R = 2,4,6-Me₃C₆H₂; 2,6-Ph₂C₆H₃)

The new aryl phosphinites PPh2OR (R = 2,4,6-Me₃C₆H₂, <b>1</b>; R = 2,6-Ph₂C₆H₃, <b>2</b>) have been prepared from chlorodiphenylphosphine and the corresponding phenols. In these ligands, the <i>ortho</i>-positions of the aromatic phosphite function are blocked by methyl and phenyl substituents, which allows coordination to metal centres without <i>ortho</i>-metallation. Thus, reaction with [PdCl₂ (cod)] leads to the complexes <i>trans</i>-[PdCl₂ (PPh₂OR)₂] (R = 2,4,6-Me₃C₆H₂, <b>3</b>; R = 2,6-Ph₂C₆H₃, <b>4</b>), while the reaction with [Rh₂ (CO)₄Cl₂] gives <i>trans</i>-[Rh(CO)Cl(PPh₂OR)2] (R = 2,4,6-Me₃C₆H₂, <b>5</b>; R = 2,6-Ph₂C₆H₃, <b>6</b>). The single-crystal X-ray structure analyses of <b>3</b> and <b>5</b> confirm the trans-coordination of the new ligands in these square-planar complexes.