Five-coordinate Pd(II) orthometallated triarylphosphite complexes

摘要

The reaction of the orthopalladated triarylphosphite complexes[{Pd(mu-Cl){kappa(2)-P,C-P(OC6H2-2,4- R-2)-(OC6H(3)-2,4-R-2)}(2)] (R = H, Bu-t) with bis(2-diphenylphosphinoethyl)phenylphosphine leads to a five-coordinate palladium(II) (R = H) and a mixture containing four- and five-coordinate species (R = Bu-t). The crystal structure of the five-coordinate species [Pd{kappa(2)-P,C-(P(OC6H4)(OC6H5)(2)}{bis(2-diphenylphosphinoethyl) phenylphosphine}][SbF6] is presented. This complex reacts with hydrogen peroxide or [AuCl(tht)] to give four- coordinate complexes in which the displaced phosphine residue is either oxidised or coordinated to gold chloride; this demonstrates that the five-coordinate complexes are labile in solution. By contrast, the reactions of the dimeric precursors with 1,1,1-tris(diphenylphosphinomethyl)ethane give four- coordinate complexes in the solid state, although evidence is presented that the smaller phosphite-containing system is five-coordinate at room temperature or higher in solution.