Reactions of manganese acetate and lanthanide acetate with Schiff-base ligands (H 3 beemp=2,6-bis[((2-(2-hydroxyethoxy)ethyl)imino)methyl]-4-methylphenol) yielded hexanuclear clusters of [Mn4IIILn2III(μ 3 -O) 2 (Hbeemp) 2 (OAc) 8 (μ 3 -OMe) 2 (H 2 O) 2 ]·C 8 H 17 OH (Ln=Gd, Tb, and Y for 1, 2, and 3, respectively). Magnetic susceptibility measurements revealed that the mixed spin systems of 1 and 2 showed ferrimagnetic behavior, while antiferromagnetic interactions were operative among Mn 3+ ions in 3. Ac magnetic susceptibility measurements for 2 showed frequency dependent in- and out-of-phase signals, confirming slow magnetic relaxation of spin reorientations.