Origin of beta-agostic interaction in d(0) transition metal alkyl complexes: Influence of ligands

Ramakrishnan, Shyama and Jemmis, Eluvathingal D (2018) Origin of beta-agostic interaction in d(0) transition metal alkyl complexes: Influence of ligands. In: JOURNAL OF ORGANOMETALLIC CHEMISTRY, 865 (SI). pp. 37-44.

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Abstract

Classical picture of agostic interaction involves a three-center two-electron interaction where the metal center has valence electron count less than sixteen. Though unsaturation on metal center is a necessary condition, it is not sufficient to show agostic interaction. For example, TiEtCl3 and its diphosphine adduct TiEtCl3(dmpe) have d(0)-metal center and the electron count is far less from 18 electrons for both. But TiEtCl3 shows no agostic interaction while TiEtCl3(dmpe) has an agostic interaction. An explanation based on negative hyperconjugation is put forward to explain the special case of C-H activation using d(0)-metal centers, which is also not sufficient. On electronic and steric grounds, TiEtCl3, rather than TiEtCl3(dmpe), is expected to exhibit agostic interaction, contrary to the experimental observation. If a molecule possesses vacant orbital in the plane of the M-C-alpha-C-beta-H fragment with appropriate energy, agostic interaction follows. How the nature and arrangement of the ligands around the metal center influence the origin of beta-agostic interaction in d(0) transition metal alkyl complexes is described in this paper. Octahedral type of arrangement of ligands around metal center help TiEtCl3(dmpe) and the pi* orbitals of CN and CF3 group help TiEt(CN)(3) and TiEt(CF3)(3) to be agostic. (C) 2018 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF ORGANOMETALLIC CHEMISTRY
Publisher:	ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Additional Information:	Copy right of this article belong to ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry Division of Interdisciplinary Sciences > Supercomputer Education & Research Centre
Date Deposited:	12 Jun 2018 16:01
Last Modified:	12 Jun 2018 16:01
URI:	http://eprints.iisc.ac.in/id/eprint/59988

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