Syntheses, structures and magnetic properties of two unprecedented hybrid compounds constructed from open Wells-Dawson anions and high-nuclear transition metal clusters.

Two new inorganic-organic hybrid compounds Na2(C3N2H12)4{[Ni5(OH)3(H2O)4(CH3CO2)][Si2W18O66]}·12.5H2O (1) and (C3N2H12)3{[Co(II)2Co(III)4(OH)5(H2O)2(CH3CO2)][Si2W18O66]}·6H2O·(C3N2H10) (2), based on lacunary polyoxometalates and high-nuclear transition-metal clusters, have been synthesized by a new method (solvothermal method). Single crystal XRD, magnetic measurements, nonlinear-optical (NLO) measurements, thermogravimetric (TG) measurements, and IR spectra were performed to analyze the structures and properties of 1 and 2. XRD analyses reveal that compound 1 consists of an open Wells-Dawson anion [Si2W18O66](16-), a five-nuclear cationic cluster [Ni5(OH)3(H2O)4(CH3CO2)](6+), free Na(+) cations, and protonated 1,3-diaminopropanes. Compound 2 has a similar structure to 1, while a six-nuclear cationic cluster [Co(II)2Co(III)4(OH)5(H2O)2(CH3CO2)](10+) replaces the five-nuclear cationic cluster [Ni5(OH)3(H2O)4(CH3CO2)](6+) in 1. Magnetic susceptibility measurements indicate antiferromagnetic interactions in 1, and the chirality of compound 2 may bring potential properties of catalysis and optical nonlinearity.