THE MOLECULAR-STRUCTURES AND MAGNETIC-PROPERTIES OF MU(3)-TETRANUCLEAR BETA-DIKETONATE COPPER-COMPLEXES [CU(BZAC)(MU(3)-OC2H4OCH3)]4 AND [CU(MU-DBM)(MU(3)-OC2H4OCH3)]4

[Cu(bzac)(OC2H4OCH3)]4dagger (I) and [Cu(dbm)(OC2H4OCH3]4dagger (II) h ave been shown to be tetrameric in the solid state. Compound I has a p seudo-cubane type structure with mu3-alkoxide oxygens occupying four b ridging positions. Two methoxy oxygens are also within bonding distanc e of copper(II) ions. Compound II has a stepped configuration with a c helate ring and alkoxide oxygens as bridging centres. None of the meth oxy oxygens is clearly chelating. Magnetic susceptibility data versus temperature data to 4 K for the complexes show antiferromagnetic coupl ing which can be treated by ''pairs of equal dimers'' procedures. The complexes decompose in stages at temperatures below 350-degrees-C at a tmospheric pressure to give CuO.