A missing high-spin molecule in the family of cyanido-bridged heptanuclear heterometal complexes, [(LCuII)(6)Fe-III(CN)(6)](3+), and its Co-III and Cr-III analogues, accompanied in the crystal by a novel octameric water cluster

Three isostructural cyanido-bridged heptanuclear complexes, [{Cu-II(saldmen)(H2O)}(6){M-III(CN)(6)}]( ClO4)(3)center dot 8H(2)O (M = Fe-III 2; Co-III, 3; Cr-III 4), have been obtained by reacting the dinuclear copper(II) complex, [Cu-2(saldmen)(2)(mu-H2O)(H2O)(2)](ClO4)(2)center dot 2H(2)O 1, with K-3[Co(CN)(6)], K-4[Fe(CN)(6)], and K-3[Cr(CN)(6)], respectively (Hsaldmen is the Schiff base resulting from the condensation of salicylaldehyde with N, N-dimethylethylenediamine). A unique octameric water cluster, with bicyclo[2,2,2] octane-like structure, is sandwiched between the heptanuclear cations in 2, 3 and 4. The cryomagnetic investigations of compounds 2 and 4 reveal ferromagnetic couplings of the central Fe-III or Cr-III ions with the Cu-II ions (J(CuFe) = +0.87 cm(-1), J(CuCr) = +30.4 cm(-1)). The intramolecular Cu center dot center dot center dot Cu exchange interaction in 3, across the diamagnetic cobalt(III) ion, is -0.3 cm(-1). The solid-state 1H-NMR spectra of compounds 2 and 3 have been investigated.