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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

The Effect of Pressure on the Anation of Diaquabis(ethane-1,2-diamine)cobalt(III) by Selenate and Sulfate, and on the Isomerization of the trans-Aquabis(ethane-1,2-diamine)(hydrogenselenito)cobalt(III) Ion

AD Fowless, GA Lawrance, DR Stranks, TR Sullivan and N Vanderhoek

Australian Journal of Chemistry 41(9) 1263 - 1273
Published: 1988

Abstract

The reversible nucleophilic substitution of cis-[Co(en)2(OH2)2]3+ (en = ethane-1,2-diamine) by sulfate and selenate at pH 2.0 was studied at elevated pressure, and activation volumes (ΔV‡) for anation and solvolysis were determined. The ΔV‡ values for anation by sulfate and selenate were +8.3±0.5 and +8.5±0.4 cm3 mol-1 respectively, whereas solvolysis of sulfato and selenato complexes cis -[Co(en)2(OH2)(XO4)]+ gave ΔV‡ values of -2.2±0.4 and -3.3±0.7 cm3 mol-1 respectively. The trans → cis [Co(en)2(OH2)(OSeO2H)]2+ isomerization studied at pH 1.0 and elevated pressure yielded ΔV‡ + 7.2±0.4 cm3 mol-1. All reactions can be interpreted in terms of dissociative mechanisms.

https://doi.org/10.1071/CH9881263

© CSIRO 1988

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