Solvothermal heterocyclic disulfide/CuX2 (X = Cl, ClO4) reactions involving dynamic S–S and C–S bond cleavage

Abstract

Under different solvothermal conditions, the reactions of 2-ppds (2-ppds = di[4-(pyridin-2-yl)pyrimidinyl]disulfide) with CuX2 (X = ClO4 or Cl) produced markedly different results because of diverse in situ reactions of 2-ppds involving dynamic S–S and C–S bond cleavage. At 90 °C, reaction of 2-ppds with Cu(ClO4)2 in CH3CN–CH2Cl2-mixed solvent yielded a discrete mononuclear complex, [Cu(L1)2(ClO4)]ClO4 (1), in which 2-ppds was converted into a zwitterion of L1 (L1 = 4-(pyridin-2-yl)pyrimidin-2-ol) involving C–S bond scission followed by attack of water. At 120 °C in DMF–MeOH solvent, reaction of 2-ppds with Cu(ClO4)2 resulted in transformation to L2 (L2 = 4-(pyridin-2-yl)pyrimidine-2-thiolate) through reductive cleavage of the S–S bond concurrent with reduction of Cu2+ to Cu+, leading to the formation of a single tetranuclear coordination complex, [Cu4(L2)4] (2), that comprises a unique Cu4S4 cluster. When the reaction between 2-ppds and CuCl2 was carried out at 90 °C in CH3CN–H2O solvent, a discrete coordination complex, [Cu(L3)(H2O)Cl]Cl (3), was obtained, resulting from conversion of 2-ppds into L3 (L3 = bis(4-(pyridin-2-yl)pyrimidin-2-yl)sulfane) through extrusion of one S atom from the S–S bond.