The ab initio gradient revolution in structural chemistry: The importance of local molecular geometries and the efficacy of joint quantum mechanical and experimental procedures

Bis(benzene)chromium. 2. Its Discovery by E. O. Fischer and W. Hafner and Subsequent Work by the Research Groups of E. O. Fischer, H. H. Zeiss, F. Hein, C. Elschenbroich, and Others†

Publisher Summary This chapter discusses those complexes in which a transition metal is π-bonded to a six-membered aromatic hydrocarbon ring Recent X-ray structural investigations along with spectroscopic and theoretical studies have contributed significantly to the understanding of the bonding in arene metal complexes The cocondensation of transition-metal atoms and aromatic hydrocarbon at liquid nitrogen temperature leads directly to zero-valent arene complexes Reaction of disubstituted acetylenes with transition-metal compounds often leads to arene complexes The direct reaction between a metal carbonyl and an aromatic hydrocarbon often leads to the replacement of 2 or 3 carbonyl groups yielding arene complexes Monoarene complexes often undergo arene replacement reactions with ligands, such as arenas The parent compound bisbenzene chromium has been the subject of several structural analyses Molecular orbital calculations have been carried out on the arene tricarbonyl complexes of Cr, Mo, and W On the basis of overlap considerations, it has been suggested that the MO framework of the arene ring may play an important role in the metal–ligand bonding in arene chromium tricarbonyl complexes Vanadium hexacarbonyl reacts with various arenes yielding complexes [(arene)V(CO) 4 ] + [V(CO) 6 ] – from which hexafluorphosphate or tetraphenylborate salts can be prepared by metathesis reaction Bisarene chromium compounds have proven to be rather inert toward arene replacement by nonaromatic ligands The exchange of one arene ligand for another in arene tricarbonyl compounds has been of some synthetic value Phosphine and phosphite ligands react with arene tricarbonyl complexes

Arene Transition Metal Chemistry

The molecular vibrations of dibenzene chromium are analyzed in terms of the eclipsed 25 atomic model of symmetry D6h with planar ligands. A complete set of symmetry coordinates is constructed and based almost entirely on conventional types of valence coordinates. A harmonic force field is given, and is used to calculate the vibrational frequencies, mean amplitudes of vibration, and perpendicular amplitude correction coefficients for (C6H6)2Cr and (C6D6)2Cr.

S. J. Cyvin

Papers

Some additional evidence for the sixfold symmetry of benzene in dibenzenechromium in the vapor phase

Normal‐koordinaten‐analyse fuer das gesamte dibenzolchrom‐molekuel

Kinematische kopplung in dicyclopentadieniden