Synthesis, structure, and magnetic properties of heterotrimetallic tetranuclear complexes

Two novel heterotrimetallic tetranuclear complexes [Cu(H2L)(CH3OH)](2)Gd(DMF)Fe(CN)(6)center dot 2H(2)O center dot DMF (1) and [Cu(H2L)(CH3OH)](2)Tb(H2O)(0.57)(DMF)(0.43)Fe(CN)(6)center dot 5.5H(2)O (2) are reported (H4L = N,N'-ethylenebis(3-hydroxysalicylidene)). The central Ln(III) ion is surrounded by two neutral [Cu(H2L)(CH3OH)] moieties, forming a Cu(2)Ln trinuclear unit. The [Fe(CN)(6)](3-) anion is weakly coordinated to one Cu(II) ion of [Cu(H2L)(CH3OH)] through a cyanide nitrogen atom with the N-Cu distance of ca. 3.2 a<<. Magnetic susceptibility measurements indicate the presence of overall ferromagnetic interactions in complexes 1 and 2. The magnetic coupling constant in complex 1 is J (Cu1Gd1) = 4.54 cm(-1) and J (Cu2Gd1) = 7.97 cm(-1) based on . Dynamic AC magnetic susceptibility studies reveal that complex 2 shows frequency-dependent out-of-phase signals, typical of single molecule magnet behavior. The energy barrier for complex 2 under a 2 kOe applied DC magnetic field is 13 K.