Ruthenium Complexes with Vinyl, Styryl, and Vinylpyrenyl Ligands: A Case of Non-innocence in Organometallic Chemistry
详细信息 查看全文
- 作者：Jö ; rg Maurer ; Michael Linseis ; Biprajit Sarkar ; Brigitte Schwederski ; Mark Niemeyer ; Wolfgang Kaim ; Stanislav Zá ; li ; Chris Anson ; Manfred Zabel ; Rainer F. Winter
- 刊名：Journal of the American Chemical Society
- 出版年：2008
- 出版时间：January 9, 2008
- 年：2008
- 卷：130
- 期：1
- 页码：259 - 268
- 全文大小：306K
- 年卷期：v.130,no.1(January 9, 2008)
- ISSN：1520-5126
文摘
We herein describe a systematic account of mononuclear ruthenium vinyl complexes L-{Ru}-CH=CH-R where the phosphine ligands at the (PR'3)2Ru(CO)Cl={Ru} moiety, the coordination numberat the metal (L = 4-ethylisonicotinate or a vacant coordination site) and the substituent R (R = nbutyl,phenyl, 1-pyrenyl) have been varied. Structures of the enynyl complex Ru(CO)Cl(PPh3)2(1:2-nBuHC=CHCCnBu), which results from the coupling of the hexenyl ligand of complex 1a with another moleculeof 1-hexyne, of the hexenyl complexes (nBuCH=CH)Ru(CO)Cl(PiPr3)2 (1c) and (nBuCH=CH)Ru(CO)Cl(PPh3)2(NC5H4COOEt-4) (1b), and of the pyrenyl complexes (1-Pyr-CH=CH)Ru(CO)Cl(PiPr3)2 (3c) and(1-Pyr-CH=CH)Ru(CO)Cl(PPh3)3 (3a-P) have been established by X-ray crystallography. All vinyl complexesundergo a one-electron oxidation at fairly low potentials and a second oxidation at more positive potentials.Anodic half-wave or peak potentials show a progressive shift to lower values as -conjugation within thevinyl ligand increases. Carbonyl band shifts of the metal-bonded CO ligand upon monooxidation aresignificantly smaller than is expected of a metal-centered oxidation process and are further diminished asthe vinyl CH=CH entity is incorporated into a more extended -system. ESR spectra of the electrogeneratedradical cations display negligible g-value anisotropies and small deviations of the average g-value fromthat of the free electron. The vinyl ligands thus strongly contribute to or even dominate the anodic oxidationprocesses. This renders them a class of truly "non-innocent" ligands in organometallic ruthenium chemistry.Experimental findings are fully supported by quantum chemical calculations: The contribution of the vinylligand to the HOMO increases from 46% (Ru-vinyl delocalized) to 84% (vinyl dominated) as R changesfrom nbutyl to 1-pyrenyl.