The magnetic behavior of the pentanuclear complex of formula Mn-II(O2CCH3)(2)[12-MCMnIII(N)shi-4](DMF)(6), 1, was investigated using magnetization and magnetic susceptibility measurements both in the solid state and in solution. Complex 1 has a nearly planar structure, made of a central Mn-II ion surrounded by four peripheral Mn-III ions. Solid state variable-field dc magnetic susceptibility experiments demonstrate that 1 possesses a low value for the total spin in the ground state; fitting appropriate expressions to the data results in antiferromangetic coupling both between the peripheral Mn-III ions (J = -6.3 cm(-1)) and between the central Mn-II ion and the Mn-III ones (J' = -4.2 cm(-1)). In order to obtain a reasonable fit, a relatively large single ion magnetic anisotropy (D) value of 1 cm(-1) was necessary for the central Mn-II ion. The single crystal magnetization measurements using a microsquid array display a very slight opening of the hysteresis loop but only at a very low temperature (0.04 K), which is in line with the ac susceptibility data where a slow relaxation of the magnetization occurs just around 2 K. In frozen solution, complex 1 displays a frequency dependent ac magnetic susceptibility signal with an energy barrier to magnetization reorientation (E) and relaxation time at an infinite temperature (tau(o)) of 14.7 cm(-1) and 1.4 x 10(-7) s, respectively, demonstrating the single molecule magnetic behavior in solution.