Reduced and Superreduced Diplatinum Complexes
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).
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.Attached Files
Supplemental Material - ja6b02559_si_001.pdf
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Additional details
- Eprint ID
- 66485
- Resolver ID
- CaltechAUTHORS:20160426-131418190
- NSF
- CHE-1305124
- Arnold and Mabel Beckman Foundation
- Ministry of Education of the Czech Republic
- LH13015
- Ministry of Education of the Czech Republic
- LD14129
- European Research Council (ERC)
- CM1202
- European Research Council (ERC)
- CM1405
- Resnick Sustainability Institute
- NSF Graduate Research Fellowship
- Created
-
2016-04-27Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- CCI Solar Fuels, Resnick Sustainability Institute