The synthesis and characterization of four dinuclear 3d-4f complexes [MIILnIII(L)(DBM)3] (ZnDy = 1, CoY = 2, CoDy = 3.3.5CH3CN, CoGd = 4.3.5CH3CN) are reported (H2L = N,N’-dimethyl-N,N’-(2-hydroxy-3-methoxy-5-methyl-benzyl)ethylenediamine, DBM- = anion of 1,3-Diphenyl-propane-1,3-dione). In the four complexes, the MII ions occupy the internal N2O2 site whereas the LnIII ions occupy the external O4 site. There are diphenoxo bridges between MII and LnIII ions in these complexes. The remaining coordination sites are occupied by three DBM- anions. Direct current (dc) magnetic susceptibility measurements indicate the presence of intramolecular ferromagnetic interactions in complexes 3 and 4. The magnetic coupling constant JCoGd in complex 4 is estimated to be 0.26 cm-1 (H = -2JCoGdSCoSGd). Alternating current (ac) magnetic susceptibility studies reveal that complexes 1 and 2 show filed-induced single molecule magnet (SMM) behavior, with ΔE values of 36.5 K and 8.56 K, respectively. Complex 3 shows frequency dependent out-of-phase signals, indicating the presence of slow relaxation of the magnetization, whereas complex 4 does not display slow magnetization relaxation.