Treatment of [NEt 4 ][(Tp ∗Me )Fe III (CN) 3 ]·H 2 O with nickel(II) trifluoromethanesulfonate affords {[(Tp ∗Me )Fe III (CN) 3 ] 2 [Ni II (DMF) 4 ] 2 [OTf] 2 }·2DMF (1) while {[(Tp ∗Me )Fe III (CN) 3 ] 2 [Ni II (bpy) 2 ] 2 [ClO 4 ] 2 }·3MeCN·2H 2 O·MeOH (2) is obtained from Ni(ClO 4 ) 2 ·6H 2 O and 2,2′-bipyridine mixtures. In the frame of an isotropic Heisenberg model, the experimental χT versus T data were modeled well with the following best set of parameters: J/k B =+9.0(4) and +8.5(4)K and g av =2.4(1) and 2.5(1) for 1 and 2, respectively; the first excited state (S=2) for 1 and 2 are ca. 18 and 16.8K above the S T =3 ground state. Analysis of the ac susceptibility suggests that 1 exhibits fast quantum tunneling of the magnetization above ca. 1.8K while 2 displays slow relaxation in the range seen for many SMMs; at H dc =2.2kOe an SMM energy barrier of Δ eff =15.7K is estimated for 2. Upon prolonged standing in air, 1 is readily transformed into a new system that exhibits a respectable energy barrier (Δ eff =20.4K) suggesting that the desolvation is able to dramatically alter the dynamics and the quantum properties of the square-shaped {Fe III 2 (μ-CN) 4 Ni II 2 }SMM.