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Aquation
About: Aquation is a research topic. Over the lifetime, 1443 publications have been published within this topic receiving 17507 citations.
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TL;DR: The first-order rate constants decrease as the amount of acid in solution increases until a limiting condition is reached as mentioned in this paper, which indicates that the reaction involved is almost entirely solvolytic aquation.
Abstract: The hydrolysis of cis-chlorohydroxylaminebis(ethylenediamine)cobalt(III) nitrate in acidic solution has been studied over a range of both acid concentrations and temperatures. At low acid concentrations, the reaction is complicated by a spontaneous redox process, and the observed first-order rate constants decrease as the amount of acid in solution increases until a limiting condition is reached (>0·4N acid); product analysis by spectrophotometry at this stage indicates that the reaction involved is almost entirely solvolytic aquation. The higher reaction rate and lower activation energy compared with the cis-chloroammine complex suggest specific hydrogen bonding of the hydroxylamine ligand which brings a water molecule into a position highly favourable for nucleophilic attack. This is assisted by the inductive effects of the hydroxyl substituent in the hydroxylamine ligand.
5 citations
5 citations
TL;DR: In this paper, the kinetics of aquation and base hydrolysis reactions ofcis-[(en)2Co(imH)O2CC6H4O-o]2+ (imH = imidazole) have been investigated in a medium of 1.0 M ionic strength.
Abstract: The kinetics of aquation and base hydrolysis reactions ofcis-[(en)2Co(imH)O2CC6H4OH-o-o]2+ (imH = imidazole) have been investigated in a medium of 1.0 M ionic strength, In the 0,1–1,0 M [H+] range (60–70°) aquation proceedsvia spontaneous and acid catalysed paths\(\left( {k_{obs} = k_{H_2 O} + k_H \left[ {H^ + } \right]} \right)\). In the 0,05–1.0 M [OH−] range (30–40°), the complex exists predominantly as the bis-deprotonated species,cis-[(en)2Co(im)O2CC6H4O-o], and the pseudo-first-order rate constant fits the relationship kobs = kb + kb° [OH−] satisfactorily. The labilizing action of coordinated imidazolate anion(im−) on the cobalt(III)-bound salicylate is 103 times stronger than that of imidazole. The mechanism is essentially Id in the aquation paths and SN1cb (Co-O bond fission) in the alkali independent and dependent paths respectively.
5 citations
01 Oct 1998
TL;DR: In this paper, the reaction of labile square-planar diethylenetriaminepalladium(II) complexes with hydrogen carbonate ion was studied by stopped flow spectrophotometry as a function of [HCO−3] and [Cl−] and constant [Pd], ionic strength and temperature to investigate the substitution behaviour with a nucleophile capable of affecting the solution pH.
Abstract: The reaction of labile square-planar diethylenetriaminepalladium(II) complexes with hydrogen carbonate ion was studied by stopped flow spectrophotometry as a function of [HCO−3] and [Cl−] and constant [Pd], ionic strength and temperature to investigate the substitution behaviour with a nucleophile capable of affecting the solution pH The kinetic results significantly deviate from those for normal square-planar substitution behaviour The reaction comprises two consecutive equilibrations, which have complex kinetics compared to the simple two-term rate law normally encountered, and which represent hydrogen carbonate inhibited and induced substitution reactions, respectively The suggested mechanism and data treatment account for the observed deviating kinetics and provide alternative ways of obtaining formerly determined aquation and anation rate constants with comparable accuracy, even for complexes too labile to be monitored directly
5 citations