Synthesis and Polymerization Performance of Pd II Complexes of New 2‐Hydroxyethyl‐Substituted Diphosphane Ligands

We have synthesized a new diphosphane ligand, 1,3‐bis[(2‐hydroxyethyl)(phenyl)phosphanyl]propane ( 2* ) ( * : mixture of meso ‐ and racemic diastereoisomers), and its corresponding neutral dichloro palladium( II ) ( 3* ), diiodo palladium( II ) ( 4* ), and dicationic diacetonitrile palladium( II ) ditetrafluoroborate ( 5* ) complexes. Separation of the 4 rac and 4 meso diastereoisomers was achieved by column chromatography and subsequent crystallization. Assignments of the particular complex geometries of 3 meso and 4 rac were facilitated by single‐crystal X‐ray diffraction analysis. After activation with MAO, complex 3* exhibits superior activity in the homopolymerization of 2‐norbornene relative to that of the dichloro Pd II derivative of 1,3‐bis(diphenylphosphanyl)propane (dppp). Compound 5* and the dppp‐analogue possess similar catalytic potentials in ethylene/CO copolymerization experiments. Applying complex 5* to propylene/CO copolymerization leads to highly regio‐ and predominantly stereoregular polyketone materials. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)