Kinetic investigations of the mechanism of dihydrogen driven catalytic reduction of methylene blue, safranine O, methyl viologen and ferricyanide using platinum carbonyl cluster anions (Chini-clusters) as catalyst
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Title |
Kinetic investigations of the mechanism of dihydrogen driven catalytic reduction of methylene blue, safranine O, methyl viologen and ferricyanide using platinum carbonyl cluster anions (Chini-clusters) as catalyst
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Creator |
SEN GUPTA, NALINAVA
MATHUR, PRADEEP DOBLE, MUKESH BHADURI, SUMIT |
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Subject |
clusters
kinetics catalysis spectra |
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Description |
[Bu4N]2[Pt12(CO)24] (1) catalyses the selective reduction of electron acceptors (S), methylene blue (MB+), safranine O (Saf+), methyl viologen (MV2+) and ferricyanide by dihydrogen. Macroscopic rate investigations for the cationic substrates in DMF, and for ferricyanide in DMSO have been carried out. In all cases, kobs is given by k1 [S] + k2, indicating that there are two catalytic cycles. In one of them, the formation of a complex between S and [Pt12(CO)24]2− in the rate determining step (rate constant k1) is followed by electron transfer and/or other fast steps. In the other catalytic cycle, the rate determining step (rate constant k2) involves formation of the solvated cluster anion [Pt12(CO)24]2−. The solvated cluster then undergoes fast reduction by dihydrogen and other reactions. The relative contributions of these two cycles depend on the substrate, and for MB+, Saf+, MV2+ and [Fe(CN)6]3− the contribution of the second cycle is about 99%, 55%, 77% and 97%, respectively. Both k1 and k2 of ferricyanide are about three orders of magnitude smaller than those of the cationic electron acceptors. The rates of reduction of MB+ and Saf+ have also been studied in the presence of added water. Rates increase as the presence of water provides an additional pathway for the reduction of [Pt12(CO)24]2− to [Pt9(CO)18]2−.
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Publisher |
Elsevier
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Date |
2009-03-04T11:37:44Z
2011-11-25T18:28:38Z 2011-12-26T13:08:20Z 2011-12-27T05:56:20Z 2009-03-04T11:37:44Z 2011-11-25T18:28:38Z 2011-12-26T13:08:20Z 2011-12-27T05:56:20Z 2006 |
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Type |
Article
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Identifier |
Inorganica Chimica Acta 359(12), 3895-3902
0009-2614 http://dx.doi.org/10.1016/S0009-2614(99)01064-7 http://hdl.handle.net/10054/856 http://dspace.library.iitb.ac.in/xmlui/handle/10054/856 |
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Language |
en
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