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,

详细信息    查看全文

• 作者：Michael I. Bruce ; Karine Costuas ; Thomas Davin ; Benjamin G. Ellis ; Jean-Franç ; ois Halet ; Claude Lapinte ; Paul J. Low ; Mark E. Smith ; Brian W. Skelton ; Loic Toupet ; and Allan H. White
• 刊名：Organometallics
• 出版年：2005
• 出版时间：August 1, 2005
• 年：2005
• 卷：24
• 期：16
• 页码：3864 - 3881
• 全文大小：327K
• 年卷期：v.24,no.16(August 1, 2005)
• ISSN：1520-6041

文摘

The reactions of FeCl(dppe)Cp* and Ru(CG SRC="/images/entities/tbd1.gif">CCges/entities/tbd1.gif">CH)L₂Cp' with Na[BPh₄] and 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu; 2 equiv) in a mixed thf/NEt₃ solvent afford {Cp*(dppe)Fe}(Cges/entities/tbd1.gif">CCges/entities/tbd1.gif">C){Ru(PP)Cp'} (PP = dppe, Cp' = Cp*, 7; PP = (PPh₃)₂, Cp' = Cp, 8). Cyclicvoltammetry shows that these mixed Fe/Ru complexes undergo sequential loss of up to threeelectrons, with the mono- and dioxidized species being isolated following chemical oxidation.Computational (DFT) and spectroscopic (IR, NMR, ESR, Mössbauer) studies are consistentwith a polarized ground-state structure with oxidation leading to the gradual evolution ofcumulenic character in the FeC₄Ru moiety and a greater degree of orbital mixing betweenthe Fe, C, and Ru centers than found in the related heterometallic complex [{Cp*(dppe)Fe}(Cges/entities/tbd1.gif">CCges/entities/tbd1.gif">C){Re(NO)(PPh₃)Cp*}]ⁿ⁺ ([6]ⁿ⁺). In contrast to the two-electron oxidationproducts derived from the diiron complex {Cp*(dppe)Fe}(Cges/entities/tbd1.gif">CCges/entities/tbd1.gif">C){Fe(dppe)Cp*} (1) andiron/rhenium complex 6, the dications [7]²⁺ and [8]²⁺ feature a dominant contribution froma singlet ground state. Thus, while 6 behaves in a manner closely related to 1, 7 and 8 aremore closely related to {Cp(Ph₃P)₂Ru}(Cges/entities/tbd1.gif">CCges/entities/tbd1.gif">C){Ru(PPh₃)₂Cp} (2) and {Cp*(dppe)Ru}(Cges/entities/tbd1.gif">CCges/entities/tbd1.gif">C){Ru(dppe)Cp*} (3), clearly demonstrating the pronounced role that choice of metalas well as formal electron count can play in tuning the electronic and magnetic propertiesof this fascinating class of compound.