Tuning the Single-Molecule Magnetism of Dysprosium Complexes by a Redox-Noninnocent Diborane Ligand

The lanthanide complexes [Cp*2Ln]­[N,N′-bpyB] (1: Ln = Dy; 3: Ln = Gd; Cp* = pentamethylcyclopentadienyl) and [222-cryptand-K]­[(Cp*2Ln)­(N,N′-bpyB)] (2: Ln = Dy; 4: Ln = Gd) bearing the redox-noninnocent diborane ligand 5,5′-bis­(dimesitylboranyl)-2,2′-bipyridine (bpyB) have been synthesized through selective reduction of bpyB to the radical anion and diamagnetic dianion states with elemental potassium in the presence of [Cp*2Ln]­[BPh4], respectively. Superconducting quantum interference device (SQUID) measurements revealed that the radical anions and the lanthanide ions in 1 and 3 exhibit an antiferromagnetic interaction. Moreover, the effective energy barrier of magnetic relaxation for 1 (18.5(9) K) is much smaller than that for 2 (77.2(5) K) under a 1 kOe field, highlighting the potential of main-group element-based redox-noninnocent ligands in tuning single-molecule magnetism.