Process for the isomerization of metallocene compounds

An isomerization process comprising:

• contacting a slurry or a solution comprising a meso or meso-like form of at least one bridged metallocene compound of group 4 of the Periodic Table of the Elements having C2 or C2-like symmetry with an isomerization catalyst of formula (I):
• [R4W]+X− (I)
• wherein W is nitrogen or phosphorus;
• R, equal to or different from each other, are C1-C40 hydrocarbon radicals optionally containing one or more heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements;
• two R can optionally join to form a saturated or unsaturated C5-C6 membered cycle containing W or two R can optionally join to form a radical of formula (II):
• wherein R1, equal to or different from each other, are C1-C20 hydrocarbon radicals optionally containing one or more heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements;
• P is phosphorous bonded with a double bond to W;
• and
• X− is a halide.