Solvent-directed Structure Variation from Mononuclear to Bis-methoxo-bridged Binuclear Copper (II) Compound: Crystal Structures and Proton-conduction

Abstract

In ethanol, the reaction of 2-(methylthio)-4-(pyridin-2-yl)pyrimidine) with Cu(NO₃)₂ (2-MTPP) yielded a mononuclear Cu(II) coordination compound [(C₁₀H₉N₃S)₂CuNO₃]NO₃.H₂O. In contrast, a discrete bis-methoxo-bridged binuclear Cu(II) coordination compound resulted when ethanol was substituted by methanol. [(C₁₀ H₉ N₃S)₂CuNO₃]NO₃.H₂O and [(C₁₀ H₉ N₃S)(CH₃O) CuNO₃]₂ have been structurally investigated by single crystal X-ray diffraction. In [(C₁₀H₉N₃S)₂CuNO₃]NO₃.H₂O, uncoordinated nitrate anions and water guest molecules form an interesting one-dimensional hydrogen-bonded chain that is accommodated into an open rhomboidal channel constructed by [Cu(NO₃)(2-MTPP)2]⁺ cations. In [(C₁₀H₉N₃S)(CH₃O)CuNO₃]₂, binuclear molecules are arrayed in a linear fashion via C–H…O hydrogen bonding interactions. Moreover, [(C₁₀H₉N₃S)₂CuNO₃]NO₃.H₂O has a proton-conductive property with a room-temperature conductivity of 4.96×10⁻⁸ S cm⁻¹.