Majumdar, Moumita ; Sinha, Arup ; Ghatak, Tapas ; Patra, Sanjib K. ; Sadhukhan, Nadanita ; Rahaman, S. M. Wahidur ; Bera, Jitendra K. (2010) Mapping the transformation [{RuII(CO)3Cl2}2]→[RuI2(CO)4]2+: implications in binuclear water–gas Shift chemistry Chemistry - A European Journal, 16 (8). pp. 2574-2585. ISSN 0947-6539
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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/chem.20...
Related URL: http://dx.doi.org/10.1002/chem.200902797
Abstract
The complete sequence of reactions in the base-promoted reduction of [{RuII(CO)3Cl2}2] to [RuI2(CO)4]2+ has been unraveled. Several μ-OH, μ:κ2-CO2H-bridged diruthenium(II) complexes have been synthesized; they are the direct results of the nucleophilic activation of metal-coordinated carbonyls by hydroxides. The isolated compounds are [Ru2(CO)4(μ:κ2-C,O-CO2H)2(μ-OH)(NPF-Am)2][PF6] (1; NPF-Am=2-amino-5,7-trifluoromethyl-1,8-naphthyridine) and [Ru2(CO)4(μ:κ2-C,O-CO2H)(μ-OH)(NP-Me2)2][BF4]2 (2), secured by the applications of naphthyridine derivatives. In the absence of any capping ligand, a tetranuclear complex [Ru4(CO)8(H2O)2(μ3-OH)2(μ:κ2-C,O-CO2H)4][CF3SO3]2 (3) is isolated. The bridging hydroxido ligand in 1 is readily replaced by a π-donor chlorido ligand, which results in [Ru2(CO)4(μ:κ2-C,O-CO2H)2(μ-Cl)(NP-PhOMe)2][BF4] (4). The production of [Ru2(CO)4]2+ has been attributed to the thermally induced decarboxylation of a bis(hydroxycarbonyl)–diruthenium(II) complex to a dihydrido–diruthenium(II) species, followed by dinuclear reductive elimination of molecular hydrogen with the concomitant formation of the RuI─RuI single bond. This work was originally instituted to find a reliable synthetic protocol for the [Ru2(CO)4(CH3CN)6]2+ precursor. It is herein prescribed that at least four equivalents of base, complete removal of chlorido ligands by TlI salts, and heating at reflux in acetonitrile for a period of four hours are the conditions for the optimal conversion. Premature quenching of the reaction resulted in the isolation of a trinuclear RuI2RuII complex [{Ru(NP-Am)2(CO)}{Ru2(NP-Am)2(CO)2(μ-CO)2}(μ3:κ3-C,O,O′-CO2)][BF4]2 (6). These unprecedented diruthenium compounds are the dinuclear congeners of the water–gas shift (WGS) intermediates. The possibility of a dinuclear pathway eliminates the inherent contradiction of pH demands in the WGS catalytic cycle in an alkaline medium. A cooperative binuclear elimination could be a viable route for hydrogen production in WGS chemistry.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to John Wiley and Sons. |
| ID Code: | 100093 |
| Deposited On: | 27 Nov 2016 13:25 |
| Last Modified: | 27 Nov 2016 13:25 |
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