Kinetics of 1 : 1 NCS–for H2O substitution on WIVof [W3(µ3-S)(µ-S)3(H2O)9]4+and [W3(µ3-S)(µ-O)3(H2O)9]4+: the effect of replacing core oxo by sulphido ligands and comparisons with MoIV3
- 1 January 1990
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 6,p. 1765-1769
- https://doi.org/10.1039/dt9900001765
Abstract
The kinetics (25 °C) of 1 : 1 complexing of NCS– for H2O at W on the incomplete cuboidal WIV 3 clusters [W3(µ3-S)(µ-S)3(H2O)9]4+ and [W3(µ3-S)(µ-O)3(H2O)9]4+ has been investigated, and together with previous data for [W3(µ3-O)(µ-O)3(H2O)9]4+, indicate the reactivity pattern for the [W3OxS4–x(H2O)9]4+(here abbreviated to W3OxS4–x 4+) series of µ-oxo/µ-sulphido aqua ions. Formation rate constants (kf/M–1s–1) in 2.00 M HClO4′I= 2.00 M are 38.4 for W3S4 4+, 0.008 0 for W3O3S4+, and 0.11 for W3O4 4+, exhibiting an identical trend to that of the corresponding MoIV 3 aqua ions, which react an order of magnitude faster. Reactions are faster at lower [H+] values indicating an involvement of conjugate-base forms of the WIV 3 reactant. From a full study on the W3S4 4+ reaction the acid-dissociation constant is Ka= 0.35 M, and rate constants are k1= 11.9 M–1 s–1 for the aqua ion, and k2= 192 M–1 s–1 for the conjugate base. This contrasts with W3O4 4+, which as far as could be ascertained proceeds exclusively by the conjugate-base route, k2= 1.2 M–1s–1. Again the behaviour observed is very similar to that for the [Mo3OxS4 –x(H2O)9]4+ series of complexes.Keywords
This publication has 21 references indexed in Scilit:
- Solution properties and reactivity of the aqua ion of the trimolybdenum(IV) incomplete cuboidal Mo/S cluster nonaaquatetrasulfidotrimolybdenum(4+)Inorganic Chemistry, 1989
- Crystal structure and mechanism of water exchange on nonaaquatetraoxotrimolybdenum(4+) from x-ray and oxygen-17 NMR studiesInorganic Chemistry, 1989
- Substitution and redox properties of the trimeric incomplete cuboidal tungsten(IV) aqua ion [W3O4(H2O)9]4+: comparisons with nonaaquatetraoxotrimolybdenum(4+)Inorganic Chemistry, 1988
- Kinetics of the substitution of thiocyanate and oxalate on nonaaquatetraoxotrimolybdenum(4+): high acidity of the aqua ligands and the dominance of conjugate-base pathwaysInorganic Chemistry, 1988
- Substitution on five µ-oxo/µ-sulphido incomplete cuboidal MoIV3ions [Mo3OxS4–x(H2O)9]4+: kinetic effects resulting from the replacement of core oxo by sulphido ligandsJournal of the Chemical Society, Chemical Communications, 1988
- Concurrent NCS–substitution at non-equivalent molybdenum(IV) centres of the incomplete cuboidal aqua ion [Mo3(µ3-S)(µ-O)(µ-S)2(H2O)9]4+J. Chem. Soc., Dalton Trans., 1988
- Structural elucidation of oligomeric aqua-molybdenum cations in solution by 17O NMRInorganica Chimica Acta, 1987
- Isotopic 18O exchange between solvent water and aquo molybdenum ionsPolyhedron, 1986
- Effect of equivalent and nonequivalent sites on the kinetics of equilibration of thiocyanate with molybdenum oxide hydrate ([Mo3O4(H2O)9]4+)Inorganic Chemistry, 1985
- Rates of isotopic oxygen exchange with solvent and oxygen atom transfer involving nonaaquatetraoxotrimolybdenum(4+) ([Mo3O4(OH2)9]4+)Inorganic Chemistry, 1985