Noncovalent interaction directing polyoxometalate assembly based on the coordination flexibility of Cu and Ag

Two new polyoxometalate supramolecular compounds based on the coordination flexibility of the last transition metal Cu and Ag, formulated as [Cu(phen)(H2O)3]0.5[Cu(phen)2(H2O)][PMo12O40] (1) and [Ag(phen)3][Ag(phen)2]3[VW12O40]·4H2O (2) (phen = 1,10-phenanthroline), have been synthesized hydrothermally and characterized by IR, TG, XPS and X-ray diffraction analyses. In 1 two kinds of Cu(II) centres present trigonal bipyramid geometries with different environments of {Cu(1)N4O} and {Cu(2)N2O3}. The silver(I) sites in 2 exhibit unusual six-coordinated {Ag(1)N6} and usual four-coordinated {Ag(2)N4} and {Ag(3)N4}. There is a trimer {[Ag(phen)2]3}3+ constructed from two Ag(2) bridged by one Ag(3) with the near distance of Ag⋯Ag = 3.310 Å.

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► Two polyoxometalate compounds with supramolecular networks were synthesized.
► The last transition metal Cu and Ag show flexible coordination modes.
► The Cu(II) centres exhibit trigonal bipyramid geometries.
► The silver(I) sites present an unusual trimer of {[Ag(phen)2]3}3+.