Ligation Behavior of an Oligo-α-sulfanylpyrazinyl Ligand in Silver(I) Complexes Containing Carboxylates

Seven new Ag­(I) complexes based on conformationally flexible 2,6-bis­(pyrazin-2-ylthio)­pyrazine (L) and selected carboxylate ligands, Ag2­(L)2­(L1)2 (1), [Ag­(L)­(L2)]∞ (2), [Ag2(L)­(L3)2]∞ (3), [Ag2(L)­(L4)2]∞ (4), {[Ag2(L)­(L5)]·​4H2O}∞ (5), {[Ag2(L)­(L6)]·​3H2O}∞ (6), and {[Ag2(L)2­(L7)]·​3H2O}∞ (7) (L1 = trifluoroacetate, L2 = heptafluorobutanoate, L3 = 4-cyanobenzoate, L4 = 2-(perfluorophenoxy)­acetate, L5 = 1,1′-biphenyl-4,4′-dicarboxylate, L6 = 2,2′-(1,4-phenylene)­diacetate, and L7 = naphthalene-2,6-dicarboxylate), have been synthesized and structurally characterized by single-crystal X-ray diffraction analyses. In 1–7, an argentophilic Ag2 dimer was found to be a dominant subunit, which is stabilized by a pair of bridging carboxylate groups. Complexes 1–4 are assembled with monocarboxylates, L, and Ag­(I) ions. Complex 1 exists as a discrete dimeric molecule, being stabilized by trans pairs of L and L1. Co-crystallization of discrete molecules and infinite chains occur in complex 2. In 3 and 4, Ag2 dimers are linked by ligands L to furnish a double-bridged chain and a ladder-like structure, respectively. Complexes 5–7 are assembled with dicarboxylate spacers and flexible L, which link Ag2 units to form a 2D slablike architecture in 5, and 3D coordination frameworks in 6 and 7. In addition, the effect of the carboxylate ligands on the ligation behavior of L and supramolecular assembly of the series of compounds are discussed in detail.