INOR 13 |
| Selective C—H bond activation is a long-standing and contemporary objective of synthetic chemistry, which pervades topics ranging from fuels and bulk chemicals to fine chemicals and pharmaceutical synthesis. Regarding the latter, conventional wisdom holds that the presence of donor heteroatoms (N, O, S, etc.) in prospective metal-mediated C—H activation targets inhibits successful C—H activation because these heteroatoms tend to bind tightly to electrophilic metal centers and prevent C—H bond coordination. We are probing this effect by studying reactions of indene and various substituted indoles with [(diimine)Pt(Me)(TFE)]+ cations (TFE = 2,2,2-trifluoroethanol). Indene displaces the TFE ligand from platinum to form a stable olefin coordination complex that undergoes C—H activation upon heating. The C—H activation reaction of indene shows first order kinetics with ΔG‡ = 29 kcal/mol, ΔS‡ = 10 eu, and KIE = 1.1 at 60 oC. Indoles also initially form coordination complexes through the 2,3 olefin, but these undergo rearrangement to the corresponding N-bound complexes. The relative rates of initial coordination and rearrangement can be controlled by pH and indole substitution.
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Coordination Chemistry: Characterization and Applications
8:40 AM-12:40 PM, Sunday, 10 September 2006 Moscone Center -- Room 301, Oral
Division of Inorganic Chemistry |
