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 CuX 2 (X = ClO 4 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(ClO 4 ) 2 in CH 3 CN-CH 2 Cl 2 -mixed solvent yielded a discrete mononuclear complex, [Cu(L1) 2 (ClO 4 )]ClO 4 (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(ClO 4 ) 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 Cu 2? to Cu ? , leading to the formation of a single tetranuclear coordination complex, [Cu 4 (L2) 4 ] (2), that comprises a unique Cu 4 S 4 cluster.When the reaction between 2-ppds and CuCl 2 was carried out at 90°C in CH 3 CN-H 2 O solvent, a discrete coordination complex, [Cu(L3)(H 2 O)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.