Coordination Assembly, Crystal Stucture And Magnetism Of The Lacunary Polyoxomolybdate With Transition Metals

Polyoxometalates (POMs), a fascinating class of metal–oxygen cluster compounds with a unique structural variety and interesting physicochemical properties, have been found to be extremely versatile inorganic building blocks in view of their potential applications in catalysis, medicine, and materials.Fifteen new compounds based on polyoxometalate building blocks have been synthesized via water solution synthesis methods, and structurally characterized by elemental analyses, IR, TG, XPS and single crystal X-ray diffractions. The thermal stabilities and magnetic properties of these compounds have been studied.1. Nine new polyoxometalate compounds based polyoxoanion cluster have been synthesized and structurally characterized: [(CH₃)4N]8[Mn(H₂O)5]2(H₃O)2 [Mn2(H₂O)10(MnAsVMo₉O₃₃)2][Mn(H₂O)4(MnAsVMo₉O₃₃)2]·20H₂O (1) (H₂NCNH₂NH₂)8(H₃O)2[Mn2(AsVMo₉O₃₃)2]·9H₂O (2) [(CH₃)4N]8[Mn(H₂O)6]4 [(MnAsVMo₉O₃₃)2]{[Mn(H₂O)5]2(MnAsVMo₉O₃₃)2}·20.5H₂O (3) [H₂N(CH₂CH₂)2O]10[Mn2(AsVMo₉O₃₃)2]·12H₂O (4) [(CH₃)3N]8[Mn(H₂O)6][(MnAsVMo₉O₃₃)2]·6H₂O (5) [(CH₃)4N]8[Co(H₂O)5]2(H₃O)2 [Co2(H₂O)10(CoAsVMo₉O₃₃)2][Co(H₂O)4(CoAsVMo₉O₃₃)2]·20H₂O (6) Na4[(CH₃)4N]4(H₃O)2[Co2(AsVMo₉O₃₃)2]·8H₂O (7) [Himi]6[As2Mo18O62]·11H₂O (imi = imidazole) (8) [H₂N(CH₂CH₂)2O]10[Cu2(AsVMo₉O₃₃)2]·5H₂O (9)The structure of 1-7 and 9 is similar to sandwich-type. Compounds 1 and 6 based on uncommon [AsVMo₉O₃₃]7- fragment which derives from the famous B-β-Keggin structure exhibits a one-dimensional chain-like framework [M(H₂O)4(MAsVMo₉O₃₃)2]8n- with isolated [M2(H₂O)14(MAsVMo₉O₃₃)2]6- units residing among the chains.2. Choosing Na2MoO4·2H₂O and NaVO3·H₂O as the starting materials, combining water solution synthesis methods, two polyoxometalates were obtained and structurally characterized: [HN(CH₃)3]10[Mn2(VMo₉O₃₃)2]·10H₂O (10) [H₂N(CH₂CH₂)2O]10[Mn2(VMo₉O₃₃)2]·5H₂O (11) [H₂N(CH₂CH₂)2O]4[Na(H₂O)2{O(CH₂CH₂)2NH₂}]2 [Na(H₂O)4]2[V10O₂8][NiMo6O₂4H6]·8H₂O (12) [H₂N(CH₂CH₂)2O]6Na2[V10O₂8H₂][NiMo6O₂4H6]·10H₂O (13)Two new complexes 10 and 11 of dinuclear manganese(II) clusters exhibit ferromagnetic interactions. In contrast to the similar structure complexes with arsenic atom as the heteroatom, which presents antiferromagnetically coupling, 10 and 11 are the rare examples of ferromagnetically coupled dinuclear manganese(II) complexes. Two new complexes 12 and 13 containing both isopolyvanadiate {V10O₂8} and [NiMo6O₂4H6]4- units have been synthesized and structurally characterized for the first time, showing that the pH value of the reaction plays a key role in structure control of self-assembled processes.3. Two compounds of the coordination of triethanolamine ligands have been synthesized in aqueous solution and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, and single-crystal X-ray diffraction: [(HOCH₂CH₂)3NH]n(H₃O)n [{Mn(H₂O)2}0.5Mn(H₂O)3{HN(CH₂CH₂O)3AsMo6O₂2}]n·3.25nH₂O (14) [Cu(H₂tea)(H₂O)(imi)][Cu(H₃tea)(imi)]Na[Mo8O₂6]·4H₂O (15)Compounds 14 is the first example of triethanolamine functionalized hexamolybdoarsenate, in which a new kind of heteropolyanion [HN(CH₂CH₂O)3AsMo6O₂2]5- is linked by Mn2+ ions forming a zig-zag chain. X-ray diffraction result reveals that theβ-[Mo8O₂6]4- polyanions of the compound 15 is linked by sodium ions to form a chain. In addition, the copper atoms are five- and six-coordinate for [Cu(H₃tea)(imi)]2+ and [Cu(H₂O)(H₂tea)(imi)]+, respectively.