Structure and Magnetism of the Tetra-Copper(II)-Substituted Heteropolyanion [Cu4K2(H2O)8(α-AsW9O33)2]8-

• DOI: 10.1021/ic034697b
• Publication Date: 2004-01-05T05:37:24Z
• Authors: Ulrich Kortz; Saritha Nellutla; Ashley C. Stowe; Naresh S. Dalal; Johan van Tol; Bassem S. Bassil
• Keywords: Tetragonal crystal system

The novel heteropolyanion [Cu(4)K(2)(H(2)O)(8)(alpha-AsW(9)O(33))(2)](8)(-) (1) has been synthesized and characterized by IR spectroscopy, elemental analysis, magnetic studies. Single-crystal X-ray analysis was carried out on [K(7)Na[Cu(4)K(2)(H(2)O)(6)(alpha-AsW(9)O(33))(2)].5.5H(2)O](n)(K(7)Na-1), which crystallizes in the tetragonal system, space group P42(1)m, with a = 16.705(4) A, b c 13.956(5) Z 2. Interaction of lacunary [alpha-AsW(9)O(33)](9)(-) Cu(2+) ions neutral, aqueous medium leads to formation dimeric polyoxoanion 1 high yield. Polyanion consists two alpha-AsW(9)O(33) units joined cyclic arrangement four K(+) ions, resulting structure C(2)(v)() symmetry. All copper have one terminal water molecule, square-pyramidal coordination geometry. Three are adjacent each other connected via micro(3)-oxo bridges. EPR studies K(7)Na-1 also Na(9)[Cu(3)Na(3)(H(2)O)(9)(alpha-AsW(9)O(33))(2)].26H(2)O (Na(9)-2) over 2-300 K yielded g values that consistent around copper(II) No hyperfine observed due presence strong spin exchange, but fine for excited (S(T) 3/2) state Na(9)-2 ground 1) K(7)Na-1. zero-field (D) parameters determined these states, constituting rare case wherein observes from both states. Magnetic susceptibility data show antiferromagnetically coupled J -1.36 +/- 0.01 cm(-)(1), while ferromagnetically (J(1) 2.78 0.13 J(2) -1.35 0.02 J(3) -2.24 0.06 cm(-)(1)), ground-state total spins S(T) 1/2