Reduced and Superreduced Diplatinum Complexes

0458890 - ÚFCH JH 2017 RIV US eng J - Journal Article
Darnton, T. V. - Hunter, B. M. - Hill, M. G. - Záliš, Stanislav - Vlček, Antonín - Gray, H. B.
Reduced and Superreduced Diplatinum Complexes.
Journal of the American Chemical Society. Roč. 138, č. 17 (2016), s. 5699-5705. ISSN 0002-7863. E-ISSN 1520-5126
R&D Projects: GA MŠMT LH13015; GA MŠMT LD14129
Grant - others:COST(XE) cm1202; COST(XE) CM1405
Institutional support: RVO:61388955
Keywords : diplatinum complexes * EPR spectrum * TD-DFT
Subject RIV: CG - Electrochemistry
Impact factor: 13.858, year: 2016

A d8–d8 complex [Pt2(μ-P2O5(BF2)4]4– (abbreviated Pt(pop-BF2)4–) undergoes two 1e– reductions at E1/2 = −1.68 and Ep = −2.46 V (vs Fc+/Fc) producing reduced Pt(pop-BF2)5– and superreduced Pt(pop-BF2)6– species, respectively. The EPR spectrum of Pt(pop-BF2)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 d8 Pt electronic configuration, making the superreduced Pt(pop-BF2)6– a very rare 6p2 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-BF2)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).
Permanent Link: http://hdl.handle.net/11104/0259105