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On the agostic interaction in lanthanide phenylene complexes: An INDO study of [(Cp 2 * M) 2 C 6 H 4 ] (M = Sc, Lu) employing an energy‐partitioning analysis
Author(s) -
Jahns V.,
Köstlmeier S.,
Kotzian M.,
Röusch N.,
Watson P. L.
Publication year - 1992
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560440514
Subject(s) - agostic interaction , lanthanide , chemistry , phenylene , crystallography , ion , organic chemistry , polymer , metal
INDO ground‐state calculations have been performed to elucidate the electronic structure of the two para ‐dimetallated σ‐phenylene complexes [(Cp 2 * M) 2 C 6 H 4 ], M = Sc, Lu. The lutetium complex exhibits an extraordinarily small MC α aryl C β arylangle of about 88°. This unusual geometry is attributed to an agostic interaction between the metal center and the (CH) 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 5 d orbitals and an agostic distortion of the geometry results.