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Disulfides, Imines, and Metal Coordination within a Single System: Interplay between Three Dynamic Equilibria
Author(s) -
Sarma Rupam J.,
Otto Sijbren,
Nitschke Jonathan R.
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701228
Subject(s) - chemistry , covalent bond , imine , disulfide bond , metal , disulfide linkage , dynamic equilibrium , transition metal , triethylamine , catalysis , polymer chemistry , organic chemistry , cysteine , biochemistry , enzyme
We report a system in which three distinct dynamic linkages, disulfide (SS), imine (CN), and coordinative (N→metal) bonds were shown to be capable of simultaneous reversible exchange. The “disulfide layer” of the system under study consists of two homo‐disulfides, bis(4‐aminophenyl) disulfide 1 and bis(4‐methoxyphenyl) disulfide 2 that equilibrate in the presence of catalytic amount of triethylamine to favor the formation of a hetero‐disulfide product, 4‐aminophenyl‐4′‐methoxyphenyl disulfide 3 . The addition of 2‐formylpyridine and a metal salt strongly perturbed this 1 + 2 ⇄ 3 equilibrium through the formation of metal complexes incorporating disulfide 1 as a subcomponent. Cu I perturbed the equilibrium by a factor of 3.3, and Fe II by a factor of 179, in both cases in favor of the homo‐disulfides. The disulfide equilibrium could be further modified, following metal‐complex formation, by coordinative (transmetallation: substitution of Fe II for Cu I ) or covalent (imine exchange: the substitution of one amine residue for another) exchange. Thus, although the three kinds of dynamic linkages were demonstrated to be mutually compatible, changes at one kind of linkage could be used to predictably perturb an equilibrium involving another.