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Evaluation of the Thermodynamic Properties of H_2 Binding in Solid State Dihydrogen Complexes [M(η^2‑H_2)(CO)dppe_2][BArF^(24)] (M = Mn, Tc, Re): An Experimental and First Principles Study

Abrecht, David G. and Fultz, Brent (2012) Evaluation of the Thermodynamic Properties of H_2 Binding in Solid State Dihydrogen Complexes [M(η^2‑H_2)(CO)dppe_2][BArF^(24)] (M = Mn, Tc, Re): An Experimental and First Principles Study. Journal of Physical Chemistry C, 116 (42). pp. 22245-22252. ISSN 1932-7447. PMCID PMC3521573. http://resolver.caltech.edu/CaltechAUTHORS:20121127-143917563

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Abstract

The solid state complex [Mn(CO)dppe_2][BArF^(24)] was synthesized, and the thermodynamic behavior and properties of the hydrogen absorption reaction to form the dihydrogen complex [Mn(η^2-H_2)dppe_2][BArF^(24)] were measured over the temperature range 313–373 K and pressure range 0–600 Torr using the Sieverts method. The absorption behavior was accurately described by Langmuir isotherms, and enthalpy and entropy values of ΔH° = −52.2 kJ/mol and ΔS° = −99.6 J/(mol K) for the absorption reaction were obtained from the Langmuir equilibrium constant. The observed binding strength was similar to metal hydrides and other organometallic complexes, despite rapid kinetics suggesting a site-binding mechanism similar to physisorption materials. Electronic structure calculations using the LANL2DZ-ECP basis set were performed for hydrogen absorption over the organometallic fragments [M(CO)dppe_2]^+ (M = Mn, Tc, Re). Langmuir isotherms derived from calculation for absorption onto the manganese fragment successfully simulated both the pressure–composition behavior and thermodynamic properties obtained from experiment. Results from calculations for the substitution of the metal center reproduced qualitative binding strength trends of 5d > 3d > 4d previously reported for the group 6 metals.


Item Type:Article
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http://dx.doi.org/10.1021/jp308176fDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp308176fPublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3521573PubMed CentralArticle
ORCID:
AuthorORCID
Fultz, Brent0000-0002-6364-8782
Additional Information:© 2012 American Chemical Society. Received: August 16, 2012. Revised: October 2, 2012. Publication Date (Web): October 15, 2012. The authors thank David Vandervelde of Caltech for his assistance with NMR experiments and Joseph Reiter and Jason Zan at the Jet Propulsion Laboratory in Pasadena, CA, for their assistance in planning thermodynamic measurements. Sieverts instrument work was performed at the Jet Propulsion Laboratory, which is operated by the California Institute of Technology under contract with NASA. The Caltech NMR facility is partially supported by the National Institutes of Health through Grant NIH RR027690. We are grateful to the Resnick Sustainability Institute for financial support. The authors declare no competing financial interest.
Group:Resnick Sustainability Institute
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Funding AgencyGrant Number
NASAUNSPECIFIED
NIHRR027690
Resnick Sustainability InstituteUNSPECIFIED
PubMed Central ID:PMC3521573
Record Number:CaltechAUTHORS:20121127-143917563
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20121127-143917563
Official Citation:Evaluation of the Thermodynamic Properties of H_2 Binding in Solid State Dihydrogen Complexes [M(η^2-H_2)(CO)dppe_2][BArF^(24)] (M = Mn, Tc, Re): An Experimental and First Principles Study David G. Abrecht and Brent Fultz The Journal of Physical Chemistry C 2012 116 (42), 22245-22252
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35685
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:27 Nov 2012 22:56
Last Modified:26 Jul 2017 16:33

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