A missing high-spin molecule in the family of cyanido-bridged heptanuclear heterometal complexes, [(LCuII)6FeIII(CN)6]3+, and its CoIII and CrIII analogues, accompanied in the crystal by a novel octameric water clusterCCDC reference numbers 755664-755667. For crystallographic data in CIF or other electronic format see DOI: 10.1039/b924505g

Three isostructural cyanido-bridged heptanuclear complexes, [{Cu II (saldmen)(H 2 O)} 6 {M III (CN) 6 }](ClO 4 ) 3 ·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 (μ-H 2 O)(H 2 O) 2 ](ClO 4 ) 2 ·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 Cu exchange interaction in 3 , across the diamagnetic cobalt( iii ) ion, is −0.3 cm −1 . The solid-state 1 H-NMR spectra of compounds 2 and 3 have been investigated. New heterometallic heptanuclear complexes have been characterized by magnetic susceptibility and NMR studies.