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|Title:||Acid Catalyzed Dissociation Kinetics of The Copper(II) and Mercury(II) Complexes of a Pendant-Arm Macrocycle|
|Authors:||Mansour M. Hassan*|
|Publisher:||Deanship of Research and Graduate Studies , Yarmouk University, Irbid , Jordan|
|Description:||Spectrophotometry and stopped-flow spectroscopy was used to study the kinetics of the acid catalyzed dissociation reactions of the complex cations of copper(II) and mercury(II) of the macrocycle cyclam with four N-pendant amide groups, (N,N ,N ,N - tetrakis (2-carbamoylethyl)-1,4,8,11-tetraazacyclotetradecane)( TCEC). The [Hg(TCEC)]2+ cation dissociates readily in aqueous acid solutions. Dissociation occurs in one composite step involving two isomers dissociating concurrently to the final products Hg2+ and the protonated ligand. Both isomers display " acid limiting(saturation) kinetics" with one isomer 6 times faster. Blue [Cu(TCEC)]2+ cation dissociates slowly in aqueous acid solutions. The dissociation process occurs in two consecutive steps, first, the blue [Cu(TCEC)]2+ cation isomerizes to the red [Cu(HTCEC)]3+ cation and secondly the red [Cu(HTCEC)]3+ cation dissociates to the final products Cu2+ and the protonated TCEC. Each of the two steps is composite and involves two isomers which isomerize and dissociate concurrently to the red [Cu(HTCEC)]3+ and the final products respectively. The isomerization of blue [Cu(TCEC)]2+ in acidic solutions displays linear dependence on [H+] with one isomer 2 times faster. While the dissociation of red [Cu(TCEC)]2+ in acidic solutions display " acid limiting(saturation) kinetics" with one isomer 6 times faster. Comparison of the dissociating rates of the [Hg(TCEC)]2+ and red[Cu(TCEC)]2+ cations in aqueous acidic solutions indicates that the former cation dissociates much more rapid by a factor 106.|
|Appears in Collections:||Journal of Chemistry|
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