ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
INDO ground-state calculations have been performed to elucidate the electronic structure of the two para-dimetallated σ-phenylene complexes [(Cp2*M)2C6H4], M = Sc, Lu. The lutetium complex exhibits an extraordinarily small M—Cαaryl—Cβaryl angle of about 88°. This unusual geometry is attributed to an agostic interaction between the metal center and the (C—H)β group of the σ-bonded aryl ring. For the analogous scandium compound, the corresponding angle is 118°, rather close to the “normal” value of 120°. Both experimental findings are very well reproduced in the computational models. An energy-partitioning analysis that exploits the features of the INDO formalism is applied in order to rationalize this geometry difference. The bending of the aryl ligand out of the plane defined by the metal coordination is favored by covalent ligand-metal interactions, but is counteracted by electrostatic repulsion effects. For the lutetium complex, the covalent interactions dominate due to the extended nature of the Lu 5d orbitals and an agostic distortion of the geometry results.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560440514
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