We report herein three pentagonal-bipyramidal holmium(III) complexes sharing the formula [Ho(L)2(py)5][BPh4], where L is the alkoxide ligand. For L = (OSi(CH3)3)−, a record energy barrier for magnetization reversal (Ueff = 715(6) K) was revealed, which is due to the pure state transition of mJ = |±8〉 → mJ = |±7〉 → mJ = |±6〉.
