Acid-catalyzed synthesis of zinc imidazolates and related bimetallic metal-organic framework compounds

A convenient method involving acid catalysis is described for the preparation of zinc imidazolate metal organic framework compounds of the type ZnIm₂ (Im = imidazolate,1,3-N₂C₃H₃) and C-substituted derivatives, including 2-Me-, 2-Et- and benzimidazolates. This method also applies to synthesis of analogous copper and cobalt imidazolates, copper–zinc bimetallic imidazolates, (Cu_aZn_bIm_2(a+b)), heterometal-doped zinc imidazolates (M_xZn_(1–x)Im₂), and multimetallic imidazolates. An unusual copper(1)-containing crystalline bimetallic imidazolate framework compound Cu₂ZnIm₄ was prepared in high yield and structurally characterized (P42₁c, a = b = 10.9623 (3), c = 6.3231 (4) Å, α = β = γ = 90°, V = 759.86 (6) ų, Z = 2). Crystal structure redeterminations were also made for tetragonal zinc imidazolate framework solid and monomeric zinc diimidazole diacetate.