Copper-, Cobalt-, and Manganese-Containing 17-Tungsto-2-Germanates.

The sandwich-type tungstogermanates [Cu[sub3](H[sub2]O)(B-β-GeW[sub8]O[sub30(OH))][sp12-] (1), [Co(H[sub2]O)[sub2]-(Co[sub3](B-β-GeW[sub9]O[sub33](OH))(B-β-GeW[sub8]O[sub30](OH)))[sub2]][sup22-] (2), and [Mn(H[sub2]O)[sub2](Mn[sub3](H[sub2]O)(B-β-GeW[sub9]O[sub33](OH))(B-β-GeW[sub8]O[sub30(OH)))[sub2][sup22-] (3) were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, and infrared spectroscopy. Polyanion 1 is composed of two nonequivalent Keggin units, (B-β-GeW[sub8]O[sub31]) and (B-β-GeW[sub9]O[sub34]), linked to each other via three copper(II) ions in such a way that there is a plane of symmetry passing through both Ge atoms and the unique Cu atom, resulting in a sandwich-type structure with C[subs] symmetry. On the other hand, the monomeric building blocks of 2 and 3 contain the same Keggin fragments as 1, but linked through three octahedrally coordinated Co[sup2+] or Mn[sup2+] ions. The major difference between complex 1 and complexes 2 and 3 is that the latter all lack a plane of symmetry due to a different orientation of the rotated triad. Magnetic measurements indicated antiferromagnetic exchange interactions between the three Cu[sup2+] ions in 1 and between the three Mn[sup2+] ions in 3. On the other hand, polyanion 2 possesses ferromagnetic interaction of the Co[sup2+] ions. The best least-squares fit values for 2 are J[subz]=7.9cm[sup-1], J[subz]=3.1 cm[sup-1], J[suby]=2.4 cm[sup-1], g[subz]6.77 cm[sup-1], and g[subxy]=4.15 (R=2.6 x 10[sup-2]). [ABSTRACT FROM AUTHOR]