Unprecedented metal-mediated in situ reactions of heterocyclic disulfide of di[4-(pyridin-2-yl)pyrimidinyl]disulfide

Abstract

By the combination of different metal salts and solvents, four unprecedented in situ reactions have been discovered for heterocyclic disulfide of 2-ppds (2-ppds = di[4-(pyridin-2-yl)pyrimidinyl]disulfide). In the CH₃CN–DMF solvent, reaction of 2-ppds with AgNO₃ produced a one-dimensional chain structure of {[Ag₂(1L)₂]·2CH₃CN}_n (1), wherein 2-ppds was converted into its sulfonate of 1L by means of oxidative cleavage of the S–S bond. In the CH₃CN–DCM solvent, reaction between 2-ppds and Cu(ClO₄)₂ yielded a discrete mononuclear Cu(II) coordination structure of [Cu(2L)₂H₂O)](ClO₄)₂ (2), of which 2-ppds was turned into a totally unexpected zwitterion product of 2Lvia C–S bond scission followed by O substitution. In the MeOH–DCM solvent, reaction of 2-ppds with Co(ClO₄)₂ resulted in a mononuclear Co(III) coordination structure of [Co(3L)₂]ClO₄·2CH₃OH·H₂O (3), in which 2-ppds was transformed into its persulfide of 3Lvia selective single C–S bond rupture. In the CH₃CN–DMF solvent, reaction between 2-ppds and CuI afforded a binuclear mixed-valence Cu^ICu^II coordination structure of [Cu₂I(4L)₂] (4), wherein 2-ppds was converted into its thiolate of 4L through homolytic S–S bond cleavage. The reaction mechanisms of these reactions have also been discussed on the basis of these in situ generated coordination structures coupled with our previous observations on 2-ppds.