The compounds of the system [M4M′2(μ3-OH)2(nbdea)4(C6H5CO2)8]·MeCN, where M = GaIII, M′ = DyIII (2), M = FeIII, M′ = YIII (3) are isostructural to the known [Fe4Dy2] compound (1). Those of the system [M4M′4(μ3-OH)4(nbdea)4(m-CH3C6H4CO2)12]·nMeCN, where M = GaIII, M′ = DyIII, n = 4 (5), M = FeIII, M′ = YIII, n = 1 (6) are isostructural to the [Fe4Dy4] compound (4). This allows for comparisons between single ion effects of the paramagnetic ions. The structures were determined using single crystal analysis. Magnetic susceptibility measurements reveal that the GaIII–DyIII compounds 2 and 5 are SMMs. The energy barrier for 2 is close to that for the known isostructural Fe4Dy2 compound (1), but with a significantly increased relaxation time.