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Organometallics 2006, 25, 5456-5465
Octahedral [TpRu(PMe3)20OR]"+ Complexes (Tp=
hydridotris(pyrazolyl)borate; R = H or Ph; n = 0 or 1): Reactions
at Ru(II) and Ru(III) Oxidation States with Substrates that Possess
Carbon-Hydrogen Bonds
Yuee Feng,t T. Brent Gunnoe,*,t Thomas V. Grimes,: and Thomas R. Cundari:
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, and
Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM),
University of North Texas, Box 305070, Denton, Texas 76203-5070
Received July 14, 2006
The Ru(II) complexes TpRu(PMe3)20R (R = H or Ph) react with excess phenylacetylene at elevated
temperatures to produce the phenylacetylide complex TpRu(PMe3)2(C=CPh). Kinetic studies indicate
that the reaction of TpRu(PMe3)20H and phenylacetylene likely proceeds through a pathway that involves
TpRu(PMe3)20OTf as a catalyst. The reaction of TpRu(PMe3)20H with 1,4-cyclohexadiene at elevated
temperature forms benzene and TpRu(PMe3)2H, while TpRu(PMe3)20OPh does not react with 1,4-
cyclohexadiene even after 20 days at 85 C. The paramagnetic Ru(III) complex [TpRu(PMe3)20H] [OTf]
is formed upon single-electron oxidation of TpRu(PMe3)20H with AgOTf. Reactivity studies suggest
that [TpRu(PMe3)20H] [OTf] initiates reactions, including hydrogen atom abstraction, with C-H bonds
that have bond dissociation energy < 80 kcal/mol. Experimentally, the O-H bond strength of the Ru(II)
cation [TpRu(PMe3)2(OH2)] [OTf] is estimated to be between 82 and 85 kcal/mol, while computational
studies yield a BDE of 84 kcal/mol, which are in reasonable agreement with the observed reactivity of
[TpRu(PMe3)O20H]+.
Introduction
Late transition metal complexes containing alkoxide, hydrox-
ide, and amido ligands play important roles in biological systems
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with nondative heteroatomic ligands have substantially increased
the number of such complexes that have been isolated and fully
characterized. ,2,6,10-16 In low oxidation states, complexes with
imido, oxo, amido, alkoxide, hydroxide, and related ligands
typically display reactivity consistent with highly basic and/or
* Corresponding author. E-mail: brent_gunnoe@ncsu.edu.
t North Carolina State University.
University of North Texas.
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10.1021/om0606385 CCC: $33.50 2006 American Chemical Society
Publication on Web 09/15/2006
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