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Reduced and Superreduced Diplatinum Complexes

Darnton, Tania V. and Hunter, Bryan M. and Hill, Michael G. and Záliš, Stanislav and Vlček, Antonín, Jr. and Gray, Harry B. (2016) Reduced and Superreduced Diplatinum Complexes. Journal of the American Chemical Society, 138 (17). pp. 5699-5705. ISSN 0002-7863. http://resolver.caltech.edu/CaltechAUTHORS:20160426-131418190

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Abstract

A d^8–d^8 complex [Pt_2(μ-P_2O_5(BF_2)_4]^(4–) (abbreviated Pt(pop-BF_2)^(4–)) undergoes two 1e– reductions at E_(1/2) = −1.68 and E_p = −2.46 V (vs Fc+/Fc) producing reduced Pt(pop-BF_2)^(5–) and superreduced Pt(pop-BF_2)^(6–) species, respectively. The EPR spectrum of Pt(pop-BF_2)^(5–) and UV–vis spectra of both the reduced and the superreduced complexes, together with TD-DFT calculations, reveal successive filling of the 6pσ orbital accompanied by gradual strengthening of Pt–Pt bonding interactions and, because of 6pσ delocalization, of Pt–P bonds in the course of the two reductions. Mayer–Millikan Pt–Pt bond orders of 0.173, 0.268, and 0.340 were calculated for the parent, reduced, and superreduced complexes, respectively. The second (5–/6−) reduction is accompanied by a structural distortion that is experimentally manifested by electrochemical irreversibility. Both reduction steps proceed without changing either d^8 Pt electronic configuration, making the superreduced Pt(pop-BF_2)^(6–) a very rare 6p^2 σ-bonded binuclear complex. However, the Pt–Pt σ bonding interaction is limited by the relatively long bridging-ligand-imposed Pt–Pt distance accompanied by repulsive electronic congestion. Pt(pop-BF_2)^(4–) is predicted to be a very strong photooxidant (potentials of +1.57 and +0.86 V are estimated for the singlet and triplet dσ*pσ excited states, respectively).


Item Type:Article
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URLURL TypeDescription
http://dx.doi.org/10.1021/jacs.6b02559DOIArticle
http://pubs.acs.org/doi/abs/10.1021/jacs.6b02559PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/jacs.6b02559PublisherSupporting Information
Additional Information:© 2016 American Chemical Society. Received: March 9, 2016. Publication Date (Web): April 11, 2016. We thank James Blakemore, Angelo Di Bilio, Yan-Choi Lam, and Jay R. Winkler for assistance with experiments and helpful discussions. This work was supported by the NSF CCI Solar Fuels Program (CHE-1305124). Additional support was provided by the Arnold and Mabel Beckman Foundation, the Ministry of Education of the Czech Republic (grants LH13015 and LD14129), and COST Actions CM1202 and CM1405. B.M.H. is a Fellow of the Resnick Sustainability Institute at Caltech; T.V.D. is an NSF Graduate Research Fellow. Author Contributions: T.V.D. and B.M.H. contributed equally. The authors declare no competing financial interest.
Group:CCI Solar Fuels, Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
NSFCHE-1305124
Arnold and Mabel Beckman FoundationUNSPECIFIED
Ministry of Education of the Czech RepublicLH13015
Ministry of Education of the Czech RepublicLD14129
European Research Council (ERC)CM1202
European Research Council (ERC)CM1405
Resnick Sustainability InstituteUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20160426-131418190
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160426-131418190
Official Citation:Reduced and Superreduced Diplatinum Complexes Tania V. Darnton, Bryan M. Hunter, Michael G. Hill, Stanislav Záliš, Antonín Vlček Jr., and Harry B. Gray Journal of the American Chemical Society 2016 138 (17), 5699-5705 DOI: 10.1021/jacs.6b02559
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66485
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 Apr 2016 03:38
Last Modified:09 May 2016 19:54

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