One-dimensional Polynuclear Spin-crossover Iron(III) Complex Axially Bridged by 1,3-Bis(4-pyridyl)propane

A one-dimensional (1D) polynuclear spin-crossover FeIII complex, [FeIII(acacen)(bpyp)]n(BPh4)n, showed a gradual and complete SC over a wide temperature range of ca. 250 K between S = 5/2 and S = 1/2, where acacen = N,N′-bis(acetylacetonato)ethylenediamine, bpyp = 1,3-bis(4-pyridyl)propane, and BPh4− = tetraphenylborate. The single-crystal X-ray structures in the HS, LS, and midpoint between the HS and LS states were determined, and demonstrated that the SC may occur through the alternately arrayed HS- and LS-chains.