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

Abstract

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