Intricacies of ligand coordination in tricarbonylchromium(0) complexes with ortho- and para-fluorobiphenyls.

The steric and electronic factors that influence which of the two rings of a substituted biphenyl ligand coordinates to chromium are of interest and it has been suggested that haptotropic rearrangements within these molecules may be limited if the arene-arene dihedral angle is too large. Two tricarbonylchromium(0) complexes and their respective free ligands have been characterized by single-crystal X-ray diffraction. In the solid state, tricarbonyl[(1',2',3',4',5',6'-η)-2-fluoro-1,1'-biphenyl]chromium(0), [Cr(CHF)(CO)], (I), exists as the more stable isomer with the nonhalogenated arene ring ligated to the metal center.