On the Electronic Structure of Bis(η5-cyclopentadienyl) Titanium

Prior to the first reported synthesis of the titanium analogue of ferrocene, bis(η5-cyclopentadienyl)Ti, there was theoretical speculation as to the electronic structure of what would become known as “titanocene”. In time, the original report of a successful synthesis was apparently shown to be incorrect, and a dimeric form of the substance was postulated as the correct structure. In the present work, high level ab initio and DFT calculations are performed on the titanocene monomer to help answer these structural questions, and to compare with early theoretical and experimental efforts. The need for a multi-configurational wave function is analyzed and found to be unnecessary. The present calculations predict that the ground state of titanocene monomer is a triplet with parallel and freely rotating cyclopentadienyl rings, which further suggests that experimentally synthesized “titanocene” is indeed some form of the dimer. Disciplines Chemistry Comments Reprinted (adapted) with permission from Journal of Physical Chemistry A 106 (2002): 7921, doi:10.1021/ jp0210226. Copyright 2002 American Chemical Society. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/chem_pubs/415 On the Electronic Structure of Bis(η5-cyclopentadienyl) Titanium Mark A. Freitag and Mark S. Gordon* Department of Chemistry, Iowa State UniVersity, Ames, Iowa 50011 ReceiVed: April 19, 2002; In Final Form: June 13, 2002 Prior to the first reported synthesis of the titanium analogue of ferrocene, bis(η5-cyclopentadienyl)Ti, there was theoretical speculation as to the electronic structure of what would become known as “titanocene”. In time, the original report of a successful synthesis was apparently shown to be incorrect, and a dimeric form of the substance was postulated as the correct structure. In the present work, high level ab initio and DFT calculations are performed on the titanocene monomer to help answer these structural questions, and to compare with early theoretical and experimental efforts. The need for a multi-configurational wave function is analyzed and found to be unnecessary. The present calculations predict that the ground state of titanocene monomer is a triplet with parallel and freely rotating cyclopentadienyl rings, which further suggests that experimentally synthesized “titanocene” is indeed some form of the dimer.