https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:8178 Zn(II)>Co(II)>Ni(II),and for M(III) and M(IV) substitution is Mn(III)~Ir(IV)>Fe(III)>Cr(III). The observed orders are consistent with the formation of metal(n+)-alcohol species as part of the reaction mechanism. For the more polarizing Ir(IV), however, Ir(IV)-alcoholate species are likely involved in the mechanism. Formation constants for the Mn(III)and Co(II)-phosphopolyoxotungstate-alcohol species with all of the above alcohols have been evaluated in 1,2-dichloroethane at 25 °C and range from 19.0-3.5 M⁻¹. The most likely transition state involves coordination of the alcohol to the transition metal substituted at the lacunary site, or alkoxide in the case of Ir(IV), along with interaction of the double bond of the alcohol with a peroxogroup located at a W(VI) site adjacent to the substituted transition metal.]]> Sat 24 Mar 2018 08:36:16 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20991 cat up to 7.3 × 10³ s⁻¹ (uncatalyzed: 3.7 × 10⁻² s⁻¹; enzyme-catalyzed: 2 × 105–1.4 × 106 s⁻¹) and a turnover number (TON) of at least 1700, limited only by the experimental conditions used. So far, no copper-based natural carbonic anhydrases are known, no faster model systems have been described and the biological role of the patellamide macrocycles is so far unknown. The observed CO₂ hydration rates depend on the configuration of the isopropyl side chains of the pseudo-octapeptide scaffold, and the naturally observed R*,S*,R*,S* geometry is shown to lead to more efficient catalysts than the S*,S*,S*,S* isomers. The catalytic efficiency also depends on the heterocyclic donor groups of the pseudo-octapeptides. Interestingly, the dicopper(II) complex of the ligand with four imidazole groups is a more efficient catalyst than that of the close analogue of ascidiacyclamide with two thiazole and two oxazoline rings. The experimental observations indicate that the nucleophilic attack of a Cu^II-coordinated hydroxide at the CO₂ carbon center is rate determining, i.e. formation of the catalyst-CO₂ adduct and release of carbonate/bicarbonate are relatively fast processes.]]> Sat 24 Mar 2018 07:50:41 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5257 Sat 24 Mar 2018 07:46:35 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5225 Sat 24 Mar 2018 07:44:21 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:18696 Mon 20 Jul 2015 17:48:34 AEST ]]>