The reaction of MnII and [NEt4]CN leads to the isolation of solvated [NEt4]Mn3(CN)7 (1) and [NEt4]2Mn3(CN)8 (2), which have hexagonal unit cells [1: Rm, a=8.0738(1), c=29.086(1) Å; 2: Pm1, a=7.9992(3), c=14.014(1) Å] rather than the face centered cubic lattice that is typical of Prussian blue structured materials. The formula units of both 1 and 2 are composed of one low- and two high-spin MnII ions. Each low-spin, octahedral [MnII(CN)6]4− bonds to six high-spin tetrahedral MnII ions through the N atoms, and each of the tetrahedral MnII ions are bound to three low-spin octahedral [MnII(CN)6]4− moieties. For 2, the fourth cyanide on the tetrahedral MnII site is C bound and is terminal. In contrast, it is orientationally disordered and bridges two tetrahedral MnII centers for 1 forming an extended 3D network structure. The layers of octahedra are separated by 14.01 Å (c axis) for 2, and 9.70 Å (c/3) for 1. The [NEt4]+ cations and solvent are disordered and reside between the layers. Both 1 and 2 possess antiferromagnetic superexchange coupling between each low-spin (S=1/2) octahedral MnII site and two high-spin (S=5/2) tetrahedral MnII sites within a layer. Analogue 2 orders as a ferrimagnet at 27(±1) K with a coercive field and remanent magnetization of 1140 Oe and 22 800 emuOe mol−1, respectively, and the magnetization approaches saturation of 49 800 emuOe mol−1 at 90 000 Oe. In contrast, the bonding via bridging cyanides between the ferrimagnetic layers leads to antiferromagnetic coupling, and 3D structured 1 has a different magnetic behavior to 2. Thus, 1 is a Prussian blue analogue with an antiferromagnetic ground state [Tc=27 K from d(χT)/dT].