Three isostructural cyanido-bridged heptanuclear complexes, [{CuII(saldmen)(H2O)}6{MIII(CN)6}](ClO4)3·8H2O (M = FeIII2; CoIII, 3; CrIII4), have been obtained by reacting the dinuclear copper(II) complex, [Cu2(saldmen)2(μ-H2O)(H2O)2](ClO4)2·2H2O 1, with K3[Co(CN)6], K4[Fe(CN)6], and K3[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 FeIII or CrIII ions with the CuII ions (JCuFe = +0.87 cm−1, JCuCr = +30.4 cm−1). The intramolecular Cu⋯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.