Synthesis, structure, and magnetic properties of Li-doped manganese-phthalocyanine, Li_x[MnPc] (0 ≤ × ≤ 4)

We report on the first synthesis of Li-intercalated manganese- phthalocyanine (MnPc) in the bulk form and on the evolution of the structural and magnetic properties as a function of Li concentration, x. We find that solid β-MnPc, which comprises rodlike assemblies of individual planar molecules, is best described as a glassy one-dimensional ferromagnet without three-dimensional ordering and that it can be quasi-continuously intercalated with Li up to x = 4, forming an isosymmetrical series of Li_x[MnPc] phases. Inserted Li⁺ ions strongly bond to pyrrole-bridging nitrogen atoms of the Pc rings, thereby disrupting the ferromagnetic Mn-N _a⋯Mn superexchange pathways. This gradually induces a crossover of the intrachain exchange interactions from ferromagnetic to antiferromagnetic as the doping level, x, increases coupled with a spin-state transition of the Mn²⁺ ions from intermediate spin, S = 3/2, to high spin, S = 5/2.