Constructing Single-Chain Magnets by Supramolecular p-p Stacking and Spin Canting: A Case Study on Manganese(III) Corroles

A single-chain magnet (SCM) was constructed from manganese(III) 5,10,15-tris(pentafluorophenyl) corrole complex [Mn-III-(tpfc)] through supramolecular pi-pi stacking without bridging ligands. In the crystal structures, [Mn(tpfc)] molecules crystallized from different solvents, such as methanol, ethyl acetate, and ethanol, exhibit different molecular orientations and intermolecular pi-pi interaction or weak Mn center dot center dot center dot O interaction to form a supramolecular one-dimensional motif or dimer. These three complexes show very different magnetic behaviors at low temperature. Methanol solvate 1 shows obvious frequency dependence of out-of-phase alternating-current magnetic susceptibility below 2 K and a magnetization hysteresis loop with a coercive field of 400 Oe at 0.5 K. It is the first example of spin-canted supramolecular single-chain magnet due to weak pi-pi stacking interaction. By fitting the susceptibility data chi T-M (20-300 K) of 1 with the spin Hamiltonian expression (H) over right arrow= -2J Sigma(n-1)(i=1) (S) over right arrow (Ai)(S) over right arrow (Ai+1) + D Sigma(i) (S) over right arrow (iZ2), the intrachain magnetic coupling parameter transmitted by pi-pi interaction of -0.31 cm(-1) and zero field splitting parameter D of -2.59 cm(-1) are obtained. Ethyl acetate solvate 2 behaves as an antiferromagnetic chain without ordering or slow magnetic relaxation down to 0.5 K. The magnetic susceptibility data chi T-M (20-300 K) of 2 was fitted by assuming the spin Hamiltonian (H) over right arrow= -2J Sigma(n-1)(i=1) (S) over right arrow (Ai) (S) over right arrow (Ai+1), and the intrachain antiferromagnetic coupling constant of -0.07 cm(-1) is much weaker than that of 1. Ethanol solvate 3 with a dimer motif shows field-induced single-molecule magnet like behavior below 2.5 K. The exchange coupling constant J within the dimer propagated by pi-pi interaction is -0.14 cm(-1) by fitting the susceptibility data cMT (20-300 K) with the spin Hamiltonian (H) over right arrow=-2J (S) over right arrow (A)(S) over right arrow (B)+ beta((S) over right arrow (AgA)+ (S) over right arrow (BgB)) H. The present studies open a new way to construct SCMs from anisotropic magnetic single-ion units through weak intermolecular interactions in the absence of bridging ligands.