Synthesis, crystal structure and magnetic propel-ties of the cyano-bridgedheteropolynuclear complex [{(Cu(dien))(2)Co(CN)(6)}(n)][Cu(dien)(H2O)Co(CN)(6)](n)center dot 5nH(2)O

The reaction of [Cu(dien)(H2O)](NO3)(2) with K-3[Co(CN)(6)] leads to the cy ano-bridged heteropolynuclear complex, [{(Cu(dien))(2)Co(CN)(6)}(n)][Cu(die n)(H2O)Co(CN)(6)](n). 5nH(2)O, {Cu3Co2}, whose crystal structure has been s olved. The structure consists of two distinct ionic units, namely one-dimen sional cationic chains [{(Cu(dien))(2)Co(CN)(6)}(n)](n+), and discrete binu clear anionic entities [(H2O)(dien)Cu-NC-Co(CN)(5)](-). The cryomagnetic in vestigation of the title compound reveals a very weak antiferromagnetic cou pling between the Cu(II) ions within the cationic chain (J=-1.02 cm(-1), g= 2.14). The complete elimination of the water molecules from the isomorphous {Cu3Co2}, {Cu3Fe2} and {Cu3Cr2} complexes causes the modification of the m agnetic properties. The most dramatic one is observed with the Cu(II)-Fe(II I) system, where the magnetic behavior changes from ferro- to antiferromagn etic. The dehydrated chromium derivative preserves the ferromagnetic coupli ng, which is observed at lower temperatures (below 30 K) in comparison with the parent compound (below 150 K). (C) 1999 Elsevier Science Ltd. All righ ts reserved.