Target syntheses of saturated Keggin polyoxometalate-based extended solids

By the approach of target synthesis, three infinitely extended hybrid compounds based on the saturated Keggin polyoxoanions have been synthesized under hydrothermal conditions: {[Co(phen)(2)](2)[(SiMO8Mo4O40)-Mo-VI-O-VI((VO)-O-IV)(2)]}{[Co(phen)(2)(H2O)](2)[(SiMo8Mo4O40)-Mo-VI-O-V ((VO)-O-IV)(2)]} center dot 3H(2)O (1),{[Co(phen)(2)](2)[(GeMo8Mo4O40)-Mo-VI-O-V((VO)-O-IV)(2)]}{[Co(phen)(2)(H2O)](2)[(GeMo8Mo4O40)-Mo-VI-O-V((VO)-O-IV)(2)]}4.8H(2)O (2)and [Ni(phen)(2)][(SiMo10Mo2O40)-Mo-IV-O-V((VO)-O-IV)(2)] center dot 2trea center dot 2H(2)O (3) (phen = 1,10-phenanthroline, trea = triethylamine). The isostructural compounds 1 and 2 belong to the monoclinic space group P2(1)/c and both contain neutral 2D layers and discrete polyoxometalate clusters decorated by transitional metal complexes. They represent an important example of the family of intercalated solids, in which both the 2D layers and the intercalated molecules are polyoxometalates with covalently linked transitional metal complex fragments. Compound 3, crystallizing in the monoclinic space group C2/c, consists of ID zigzag chains constructed from alternating [(SiMo10Mo2O40)-Mo-VI-O-V((VO)-O-IV)(2)](2-) polyoxoanions and [Ni(phen)(2)](2+) fragments. More interestingly, these three compounds are constructed directly from saturated polyoxometalates, in which the intact skeletons of Keggin clusters are maintained under hydrothermal conditions. Variable-temperature magnetic susceptibility measurements of compounds I and 2 reveal the feature of antiferromagnetic exchange interaction in these compounds. (c) 2005 Elsevier B.V. All rights reserved.