Iron versus ruthenium: Dramatic changes in electronic structure result from replacement of one Fe by Ru in [{Cp*(dppe)Fe}-CC-CC-{Fe(dppe)Cp*}]n+ (n=0, 1, 2)
Date
2005
Authors
Bruce, M.
Costuas, K.
Davin, T.
Ellis, B.
Halet, J.
Lapinte, C.
Low, P.
Smith, M.
Skelton, B.
Toupet, L.
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Journal article
Citation
Organometallics, 2005; 24(16):3864-3881
Statement of Responsibility
Michael I. Bruce, Karine Costuas, Thomas Davin, Benjamin G. Ellis, Jean-Franois Halet, Claude Lapinte, Paul J. Low, Mark E. Smith, Brian W. Skelton, Loic Toupet, and Allan H. White
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Abstract
The reactions of FeCl(dppe)Cp* and Ru(C≡CC≡CH)L <inf>2</inf>Cp′ with Na[BPh<inf>4</inf>] and 1,8-diazabicyclo[5.4.0]undec- 7-ene (dbu; 2 equiv) in a mixed thf/NEt<inf>3</inf> solvent afford (Cp*(dppe)-Fe}(C≡CC≡C){Ru(PP)Cp′} (PP = dppe, Cp′ = Cp*, 7; PP = (PPh<inf>3</inf>)<inf>2</inf>, Cp′ = Cp, 8). Cyclic voltammetry shows that these mixed Fe/Ru complexes undergo sequential loss of up to three electrons, with the mono- and dioxidized species being isolated following chemical oxidation. Computational (DFT) and spectroscopic (IR, NMR, ESR, Mössbauer) studies are consistent with a polarized ground-state structure with oxidation leading to the gradual evolution of cumulenic character in the FeC<inf>4</inf>Ru moiety and a greater degree of orbital mixing between the Fe, C, and Ru centers than found in the related heterometallic complex [{Cp*(dppe)-Fe}(C≡CC≡C){Re(NO)(PPh<inf>3</inf>)Cp*}] <sup>n+</sup> ([6]<sup>n+</sup>). In contrast to the two-electron oxidation products derived from the diiron complex {Cp*(dppe)Fe}(C≡CC≡C) {Fe(dppe)Cp*} (1) and iron/rhenium complex 6, the dications [7] <sup>2+</sup> and [8]<sup>2+</sup> feature a dominant contribution from a singlet ground state. Thus, while 6 behaves in a manner closely related to 1, 7 and 8 are more closely related to {Cp(Ph<inf>3</inf>P)<inf>2</inf>Ru} (C≡CC≡C){Ru(PPh<inf>3</inf>)<inf>2</inf>Cp} (2) and {Cp*(dppe)Ru}-(C≡CC≡C){Ru(dppe)Cp*} (3), clearly demonstrating the pronounced role that choice of metal as well as formal electron count can play in tuning the electronic and magnetic properties of this fascinating class of compound. © 2005 American Chemical Society.
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Publication Date (Web): July 1, 2005
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Copyright © 2005 American Chemical Society