Multidimensional metal-organic frameworks constructed from flexible bis(imidazole) ligands

Two structurally related flexible bis(imidazole) ligands, N,N'-(1,1-methyl)bis(imidazole) (L-1) and N,N'-(1,4-butanediyl)bis(imidazole) (L-2) reacted with Ag-I, Cu-II, Zn-II, and Cd-II salts under hydrothermal conditions (except for 2 at room temperature), resulted in the formation of eight novel metal-organic coordination architectures, from one-dimensional (1D) chain to three-dimensional (3D) network structures: {[Ag(L-1)(2)]ClO4}(n) (1), {[Cu(L-1)(2)(H2O)(2)]-Cl-2(H2O)(0.5)(acetone)}(n) (2), {[Cu(L-1)(2)] (BF4)(2)}(n) (3), {[Cu(L-1)(2)](ClO4)(2)}(n) (4), {[Zn(L-1)(3)](ClO4)(2)}(n) (5), {[Cd(L-1)(3)](ClO4)(2)}(n) (6), {[Cd(L-1)(2)](N-3)(2)}(n) (7), and {[Zn(L-2)(2)]ClO4)(2)}(n) (8). All complexes have been structurally characterized by X-ray diffraction analysis. In 1, the Ag-I centers are two-coordinate with linear geometry and L-1 ligands bridge the Ag-I centers to form 1D single helical chains. 2 and 7 have 1D double chain structures with the central metal ions being six-coordinated by four discrete L-1 and two apical ligands (water molecules for 2 and N-3(-) for 7). 3 and 4 are isostructural two-dimensional (2D) (4,4) networks with square planar Cull centers. 5 and 6 also are isostructural with CdSO4-like 3D framework structures. In 8, the Zn-II ions are tetrahedral, and each L-2 ligand links two Zn-II ions to form a 1D double chain.