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A 3D mixed-valence Co(III)-Co(II) compound [Co9(bta)10(Hbta)2(H2O)10] n ·[22(H2O)] n ( 1 ) (H2bta= N , N -bis(1 H -tetrazole-5-yl)-amine) was hydrothermally synthesized by reaction of Co(NO3)2·6H2O with H2bta·H2O. Compound 1 consists of three kinds of distorted-octahedral [CoII(N4O2)] paramagnetic nodes which are separated by [CoIII(bta)2(Hbta)]2-/[CoIII(bta)3]3- diamagnetic linkers to generate a 3D porous metal-organic framework (MOF) with alternative …Co(III)…Co(II)… array and channels incorporating water molecules. Under an applied magnetic field of 4000 Oe, compound 1 exhibits slow relaxation of magnetization at low temperatures, giving Δ E / k B =30.00 K and t 0=2.0×10-8 s.

Six lanthanide compounds [Ln(H2O)9](m-BDTH)3·9(H2O) where Ln = La (1), and [Ln(H2O)8](m-BDTH)3·9(H2O) (m-BDTH2 = 1,3-benzeneditetrazol-5-yl) where Ln = Lu (2), Yb (3), Er (4), Ho (5) and Y (6) were hydrothermally synthesized and characterized by elemental analyses, infrared spectra, powder X-ray diffraction (PXRD) and X-ray single crystal diffraction. PXRD indicates that 2–6 are isomorphous. Structural analyses reveal that 1 is coordinated by nine water molecules forming a capped-square antiprism, while 2–6 are coordinated by eight water molecules forming a simple square antiprismatic geometry. Effects of water molecules on thermal stability were also discussed by thermogravimetric (TG), DSC, and PXRD under different temperatures. TG analyses suggest that 1 loses lattice and coordinated water molecules with no diacritical boundary, and 6 removes lattice water molecules first and then coordinated water molecules. DSC and PXRD further confirm the consequence.