Fully Delocalized (Ethynyl)(vinyl)phenylene Bridged Triruthenium Complexes in up to Five Different Oxidation States
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- 作者：Evelyn Wuttke ; Florian Pevny ; Yves-Marie Hervault ; Lucie Norel ; Malte Drescher ; Rainer F. Winter ; St茅phane Rigaut
- 刊名：Inorganic Chemistry
- 出版年：2012
- 出版时间：February 6, 2012
- 年：2012
- 卷：51
- 期：3
- 页码：1902-1915
- 全文大小：751K
- 年卷期：v.51,no.3(February 6, 2012)
- ISSN：1520-510X
文摘
Triruthenium [(dppe)2Ru{鈭扖鈮鈥?,4-C6H2鈥?,5-R2鈥揅H鈺怌H鈥揜uCl(CO)(PiPr3)2}2]n+ (4a, R = H; 4b, R = OMe) containing unsymmetrical (ethynyl)(vinyl)phenylene bridging ligands and displaying five well-separated redox states (n = 0鈥?) are compared to their bis(alkynyl)ruthenium precursors (dppe)2Ru{鈭扖鈮鈥?,4-C6H2鈥?,5-R2鈥揅鈮R鈥瞹 (2a,b: R鈥?= TMS; 3a,b: R鈥?= H) and their symmetrically substituted bimetallic congeners, complexes {Cl(dppe)2Ru}2{渭-C鈮鈥?,4-C6H2鈥?,5-R2鈥揅鈮} (Aa, R = H; Ab, R = OMe) and {RuCl(CO)(PiPr3)2}2{渭-CH鈺怌H鈥?,4-C6H2鈥?,5-R2鈥揅H鈺怌H} (Va, R = H; Vb, R = OMe) as well as the mixed (ethynyl)(vinyl)phenylene bridged [Cl(dppe)2Ru鈥揅鈮鈥?,4-C6H4鈥揅H鈺怌H鈥揜uCl(CO)(PiPr3)2] (Ma). Successive one-electron transfer steps were studied by means of cyclic voltammetry, EPR and UV鈥搗is鈥揘IR鈥揑R spectroelectrochemistry. These studies show that the first oxidation mainly involves the central bis(alkynyl) ruthenium moiety with only limited effects on the appended vinyl ruthenium moieties. The second to fourth oxidations (n = 2, 3, 4) involve the entire carbon-rich conjugated path of the molecule with an increased charge uniformly distributed between the two arms of the molecules, including the terminal vinyl ruthenium sites. In order to assess the charge distribution, we judiciously use 13CO labeled analogues to distinguish stretching vibrations due to the acetylide triple bonds and the intense and charge-sensitive Ru(CO) IR probe in different oxidation states. The comparison between complex pairs 4a,bn+ (n = 0鈥?), Aa,bn+ and Va,bn+ (n = 0鈥?) serves to elucidate the effect of the methoxy donor substituents on the redox and spectroscopic properties of these systems in their various oxidation states and on the metal/ligand contributions to their frontier orbitals.