Polymerizing Cluster Helicates into High-Connectivity Networks

Solvothermal reactions of Cu-II salts and 3,5-bis(4-pyridyi)pyrazole (HL) under various conditions gave three different types of crystalline compound, namely [Cu-2(Cu5L6)]BF4 center dot 5H(2)O (1a), [Cu-2(Cu5L6)]ClO4 center dot 5H(2)O (1b) and [Cu-2(CN)(2)(Cu5L6)(2)][BF4](3) (2). 1a and b were obtained in ethanol and NH3 center dot H2O, whereas 2 was obtained in methanol and NH3 center dot H2O. The three complexes were constructed by incorporating new pentanuclear copper(l) pyrazolate bis(triple helical) cluster helicates (Cu5L6) as the second building units (SBUs), in which as many its twelve 4-pyridyl N atoms are available for further coordination and construction of high-connectivity topological networks. In la and b, seven 4-pyridyl N atoms are linked to three three-coor-dinated Cut atoms and four four-coordinated Cut atoms, which results in 3,4,7-connected networks. In 2, as many as eleven 4-pyridyl N atoms coordinate to eleven Cul atoms, which results in a 4,10-connected topological network. The increasing connectivity of the cluster nodes in 2 is closely related to the in situ-formed CN- anion bridge around the periphery of the pentanuclear cluster helicates. The luminescent properties of these compounds were also investigated.