Interaction of the Trinuclear Triangular Secondary Building Unit [Cu3(μ3-OH)(μ-pz)3]2+with 4,4′-Bipyridine. Structural Characterizations of New Coordination Polymers and Hexanuclear CuIIClusters. 2°

By reacting 4,4'-bipyridine (bpy) with selected trinuclear triangular Cu-II complexes, [Cu-3(mu(3)-OH)(mu-pz)(3)(RCOO)(2)(LL')] [pz = pyrazolate anion; R = CH3, CH3CH2, CH2=CH, CH2=C(CH3); L, L' = Hpz, H2O, MeOH] in MeOH, the substitution of monotopic ligands by ditopic bpy was observed. Depending on the stoichiometric reaction ratios, different compounds were isolated and structurally characterized. One- and two-dimensional coordination polymers (CPs), as well as two hexanuclear Cu-II clusters were identified. One of the hexanuclear clusters self-assembles into a supramolecular three-dimensional structure, and its crystal packing shows the presence of two intersecting channels, one of which is almost completely occupied by guest bpy, while in the second one guest water molecules are present. This compound also shows a reversible, thermally induced, single-crystal-to-single-crystal transition.