Four Hybrid Materials Based on Preyssler P₅W₃₀ Polyoxometalate and First-Row Transition-Metal Complex

Four Preyssler P₅W₃₀ based inorganic–organic hybrids, formulated as {[Cu₁₂(pbtz)₂(Hpbtz)₂­(OH)₄(H₂O)₁₆]­[Na­(H₂O)­P₅­W₃₀O₁₁₀]}·16H₂O (1; H₂pbtz = 5′-(pyridin-2-yl)-1H,2′H-3,3′-bi­(1,2,4-triazole)), {[Cu₁₀(ttbz)₂(Httbz)₄­(OH)₆(H₂O)₈]­[K­(H₂O)­H₂P₅W₃₀O₁₁₀]}·30H₂O (2; Httbz = 1-(tetrazo-5-yl)-4-(triazo-1-yl)­benzene), {[Ni₆(bpz)₆(H₂O)₁₆]­[Na­(H₂O)­H₂P₅W₃₀O₁₁₀]}·36H₂O (3; bpz = 3,3′,5,5′-tetramethyl-4,4-bipyrazole), {[Co₄(bpz)₆(H₂O)₉]­[K­(H₂O)­H₆P₅­W₃₀O₁₁₀]}·46H₂O (4), have been isolated and structurally identified via microanalysis, thermogravimetry (TG), infrared (IR) spectroscopy, and X-ray single-crystal diffraction. Compound 1 exhibits a 3D binodal (3,6)-connected ant framework composed of dodeca-supported P₅W₃₀ polyoxometalate (POM) clusters and discrete [Cu₆(pbtz)­(Hpbtz)­(OH)₂(H₂O)₈] subunits. Compound 2 is a pillared-layer 3D network constructed from [Cu₅(ttbz)­(Httbz)₂­(OH)₃(H₂O)₄] sheets pillared by individual P₅W₃₀ clusters. Compound 3 contains octa-supporting P₅W₃₀ POM clusters and novel [Ni₆(bpz)₆] crown-like metallamacrocycles, which construct a (4,4)-connected pts network. Compound 4 displays a complicated 3D (5,5)-connected {4⁵·6⁴·8}­{4⁵·6⁵} network built by pentasupporting P₅W₃₀ POM clusters and discrete [Co₄(bpz)₆(H₂O)₉] subunits. In 1–4, the unified features are the Preyssler-type [P₅W₃₀O₁₁₀] POM as the fundamental building block, which supports the transition-metal compounds with different modes to give the resultant diverse networks. The magnetism studies indicated antiferromagnetically coupled systems for the hexa- and pentanuclear Cu­(II) units in 1 and 2, respectively. The electrochemical properties demonstrate that all compounds have electrocatalytic abilities toward the reduction of hydrogen peroxide. Furthermore, the catalytic activities of 1 in the cyanosilylation of aldehydes reaction have been investigated.