The rates of water exchange in Al(III)-salicylate and Al(III)-sulfosalicylate complexes
- Univ. of California, Davis, CA (United States)
Rate parameters are reported for exchange of hydration waters from the inner coordination sphere of Al(III)-sulfosalicylate [Al(sSal){sup +}] and Al(III)-salicylate [Al(Sal){sup +}] complexes to bulk solution as determined with {sup 17}O-NMR. The rate parameters for the Al(sSal){sup +} complex are: K{sub ex}{sup 298} = (3.0 {+-} 0.2){center_dot}10{sup 3} s{sup {minus}1}, {Delta}H{sup {double_dagger}} = 37({+-}3)kJ/mol, {Delta}S{sup {double_dagger}} = {minus}54({+-}9) J/mol K; and for the Al(Sal){sup +} complex are: k{sub ex}{sup 298} = 4.9({+-}0.3){center_dot}10{sup 3} s{sup {minus}1}, {Delta}H{sup {double_dagger}} = 35({+-}3) kJ/mol, {Delta}S{sup {double_dagger}} = {minus}57({+-}11) J/mol K. These results, along with previous work, suggest that the lability of water molecules in bidentate carboxylate-phenolic complexes scales with the electron-donating properties of the ligand oxygens. Replacement of a coordinated carboxyl with a phenolic group in the ligand increases both the Lewis basicity and the value of k{sub ex}{sup 298}. A correlation between these parameters is proposed that can be used to predict rate coefficients for other bidentate aluminum complexes.
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- FG03-96ER14629
- OSTI ID:
- 364119
- Journal Information:
- Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: 10 Vol. 63; ISSN GCACAK; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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