Construction of Mono-, Bi- and Trinuclear Clusters to Modify Wells-Dawson Anions through Using Different Transition Metals and Flexible Bis(Pyrazole) Ligands

Three new Wells-Dawson compounds, namely [Co-II(edpz)(H(2)bdpm)(3)][(H4P2W18O62)] (1), [Cd-2(II)(mpz)(H(2)bhpe)(2.5)(H2O)(H2P2W18O62)] center dot (ppz) center dot 6H(2)O (2) and [Cu-3(II)(ppz)(H(2)bhpe)(2)(P2W18O62)(H2O)(3)] center dot 2H(2)O (3) (edpz = 4-ethyl-3,5-dimethyl-1H-pyrazole, H(2)bdpm = 1,1'-bis(3,5-dimethyl-1H-pyrazolate)methane, mpz = 4-methyl-4H-pyrazole, H(2)bhpe = 1,2-bis(1H-pyrazolyl)ethane, ppz = 4-propyl-1H-pyrazole), have been hydrothermally synthesized by using flexible bis(pyrazole) ligands and characterized by single-crystal X-ray diffraction analysis, IR spectra and elemental analyses. In compound 1, there are two discrete subunits: a mono-nuclear [Co(edpz)(H(2)bdpm)(3)](2+) cluster and a Wells-Dawson anion. The hydrogen bonding interactions between these subunits induce a 2D supramolecular structure. In compound 2, two Cd ions are fused by one mpz and five H(2)bhpe ligands to construct a bi-nuclear Cd cluster. The [P2W18O62](6-) anions link bi-nuclear Cd clusters to form a 3D framework. In compound 3, four H(2)bhpe ligands fuse three Cu-II ions to construct a planar tri-nuclear cluster, with one ppz ligand vertical with this tri-nuclear cluster. The [P2W18O62](6-) anions connect adjacent tri-nuclear clusters to form a 3D framework. Moreover, we also investigated the electrochemical and photocatalytic properties of compounds 1-3.