Kinetic Studies of Water Exchange and Substitution by NCS– on the Sulphur-capped Triangular Ion [Μο3(μ3-S)(μ-O)3(ΟΗ2)9]4+
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Gabor Lente
Abstract
A kinetic study of water exchange and NCS complexation on the mixed oxo-sulphido aqua complex [Μο3(μ3-S)(μ-O)3(ΟΗ2)9]4+ is reported along with structural (Mo Kedge EXAFS) and electronic (95MO NMR) data. The complex possesses nonequivalent water ligands with those labelled 'd' (two per Mo), located approximately trans to μ-οχο, undergoing exchange ~3 x 104 times faster than those labelled 'c' (one per Mo), located approximately trans to the capping μ3-sulphido group. The faster rate for the former arises, as with the all μ-sulphido cluster, [Mo3(μ3-S)(μ-S)3(OH2)9]+4 from a conjugate-base labilising pathway involving the monohydroxy species, [Μο3(μ3-S)(μ-O)3(ΟΗ2)8(ΟΗ)]3+ (KaM = 0.58M estimated from the [Η+ ] dependence of the anation reaction with NCS-). Deprotonation at an adjacent water'd' on the same Mo atom is suggested. Taken together, the substitution and water exchange data gathered on this family of cluster ions is consistent with dissociative ligand substitution preferentially at a water 'd' on the monohydroxy species in all cases. Substitution of sulphido for oxo in the two core positions affects mainly the exchange at water'd'; substitution at the μ3-capping position retarding the rate of exchange by a factor of ~ 4 (no effect on water 'c') whereas similar substitution at all three μ-bridging positions increases the rate of the water 'd' exchange ~200-fold but that on water 'c' only ~11-fold. These along with the 95Mo NMR with Mo Kedge EXAFS data suggest that the observed kinetic effects stemming from changes to the capping μ3-ligand may be largely structural in nature whereas a direct electronic influence (affecting most noticeably water'd') is implied for the μ-bridging ligands.
© 2014 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Editorial
- Dedicated to Ralph G. Wilkins
- Kinetic Studies of Water Exchange and Substitution by NCS– on the Sulphur-capped Triangular Ion [Μο3(μ3-S)(μ-O)3(ΟΗ2)9]4+
- A Kinetic Study of the Photolysis of Ethylferrocene in Chloroform
- Oxidation of Thioglycolic Acid by Nickel(IV) Oxime-Imine Complexes - A Kinetic and Mechanistic Approach
- The Copper(II)-2,2′-Dipyridylamine Catalysed Hydrolysis of the Phosphotriester 2,4-Dinitrophenyl Diethyl Phosphate and O-isopropyl Methylfluorophosphonate (Sarin)
- Oxidation of Thiol-containing Substrates by the Pentaamminechromatocobalt(III) Complex Ion
- Complex Formation of Iron(II/III) with [15]aneN4 in Aqueous Solution. Kinetics of the Oxidation of FeII([15]aneN4) by Dioxygen
- Hydrogen Atom Abstraction by Methyl Radicals from tert-Butyl Hydroperoxide in a Modified Fenton Reaction
- The Rate of Electron Self-Exchange in the System [CuIL]+/[CuIIL]2+ with L = 2,2′-Bis(3-(2-pyridyl)-l-methyltriazolyl)biphenyl
- Notes for Contributors Inorganic Reaction Mechanisms
- Disk Specifications
- Journal Order Form
Articles in the same Issue
- Editorial
- Dedicated to Ralph G. Wilkins
- Kinetic Studies of Water Exchange and Substitution by NCS– on the Sulphur-capped Triangular Ion [Μο3(μ3-S)(μ-O)3(ΟΗ2)9]4+
- A Kinetic Study of the Photolysis of Ethylferrocene in Chloroform
- Oxidation of Thioglycolic Acid by Nickel(IV) Oxime-Imine Complexes - A Kinetic and Mechanistic Approach
- The Copper(II)-2,2′-Dipyridylamine Catalysed Hydrolysis of the Phosphotriester 2,4-Dinitrophenyl Diethyl Phosphate and O-isopropyl Methylfluorophosphonate (Sarin)
- Oxidation of Thiol-containing Substrates by the Pentaamminechromatocobalt(III) Complex Ion
- Complex Formation of Iron(II/III) with [15]aneN4 in Aqueous Solution. Kinetics of the Oxidation of FeII([15]aneN4) by Dioxygen
- Hydrogen Atom Abstraction by Methyl Radicals from tert-Butyl Hydroperoxide in a Modified Fenton Reaction
- The Rate of Electron Self-Exchange in the System [CuIL]+/[CuIIL]2+ with L = 2,2′-Bis(3-(2-pyridyl)-l-methyltriazolyl)biphenyl
- Notes for Contributors Inorganic Reaction Mechanisms
- Disk Specifications
- Journal Order Form
