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Transition State Characterization for the Reversible Binding of Dihydrogen to Bis(2,2'-bipyridine)rhodium(I) from Temperature- and Pressure-Dependent Experimental and Theoretical Studies

Fujita, Etsuko and Brunschwig, Bruce S. and Creutz, Carol and Muckerman, James T. and Sutin, Norman and Szalda, David and van Eldik, Rudi (2006) Transition State Characterization for the Reversible Binding of Dihydrogen to Bis(2,2'-bipyridine)rhodium(I) from Temperature- and Pressure-Dependent Experimental and Theoretical Studies. Inorganic Chemistry, 45 (4). pp. 1595-1603. ISSN 0020-1669. https://resolver.caltech.edu/CaltechAUTHORS:20170607-132954318

[img] PDF (Crystal data and structure refinement, and other X-ray crystallographic data in CIF format; conversion of standard states; DFT-optimized Cartesian coordinates for RhI(bpy)2+, RhIII(H)2(bpy)2+, and the transition-state complex; complete bond distances ...) - Supplemental Material
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Abstract

Thermodynamic and kinetic parameters for the oxidative addition of H_2 to [Rh^I(bpy)_2]^+ (bpy = 2,2‘-bipyridine) to form [Rh^(III)(H)_2(bpy)_2]^+ were determined from either the UV−vis spectrum of equilibrium mixtures of [Rh^I(bpy)_2]^+ and [Rh^(III)(H)_2(bpy)_2]^+ or from the observed rates of dihydride formation following visible-light irradiation of solutions containing [Rh^(III)(H)_2(bpy)_2]^+ as a function of H_2 concentration, temperature, and pressure in acetone and methanol. The activation enthalpy and entropy in methanol are 10.0 kcal mol^(-1) and −18 cal mol^(-1) K^(-1), respectively. The reaction enthalpy and entropy are −10.3 kcal mol^(-1) and −19 cal mol^(-1) K^(-1), respectively. Similar values were obtained in acetone. Surprisingly, the volumes of activation for dihydride formation (−15 and −16 cm^3 mol^(-1) in methanol and acetone, respectively) are very close to the overall reaction volumes (−15 cm^3 mol^(-1) in both solvents). Thus, the volumes of activation for the reverse reaction, elimination of dihydrogen from the dihydrido complex, are approximately zero. B3LYP hybrid DFT calculations of the transition-state complex in methanol and similar MP2 calculations in the gas phase suggest that the dihydrogen has a short H−H bond (0.823 and 0.810 Å, respectively) and forms only a weak Rh−H bond (1.866 and 1.915 Å, respectively). Equal partial molar volumes of the dihydrogenrhodium(I) transition state and dihydridorhodium(III) can account for the experimental volume profile found for the overall process.


Item Type:Article
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URLURL TypeDescription
http://dx.doi.org/10.1021/ic0515498DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ic0515498PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ic0515498PublisherSupporting Information
ORCID:
AuthorORCID
Brunschwig, Bruce S.0000-0002-6135-6727
Additional Information:© 2006 American Chemical Society. Received September 9, 2005. Publication Date (Web): January 5, 2006. We thank Percefoni Doufou, Hideo Konno, and Mohamed S. A. Hamza for obtaining preliminary data. R.v.E. and M.S.A.H. gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft and the Alexander von Humboldt Foundation. X-ray data collection was performed with help of Dr. Jonathan Hanson at Beam Line X7B of the National Synchrotron Light Source at Brookhaven National Laboratory. This work was performed at BNL, funded under contract DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences.
Funders:
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Department of Energy (DOE)DE-AC02-98CH10886
Issue or Number:4
Record Number:CaltechAUTHORS:20170607-132954318
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170607-132954318
Official Citation:Transition State Characterization for the Reversible Binding of Dihydrogen to Bis(2,2'-bipyridine)rhodium(I) from Temperature- and Pressure-Dependent Experimental and Theoretical Studies Etsuko Fujita, Bruce S. Brunschwig, Carol Creutz, James T. Muckerman, Norman Sutin, David Szalda, and, Rudi van Eldik Inorganic Chemistry 2006 45 (4), 1595-1603 DOI: 10.1021/ic0515498
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78006
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Jun 2017 22:39
Last Modified:03 Oct 2019 18:04

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