Abrupt Spin‐State Switching in Mn(III) Complexes with BPh<sub>4</sub> Anion: Effect of Halide Substituents on Crystal Structure and Magnetic Properties.
Aleksandra V. Tiunova, Anna V. Kazakova, Денис В. Корчагин, G.V. Shilov, Leokadiya V. Zorina, Sergey V. Simonov, Konstantin V. Zakharov, Aleksander N. Vasiliev, Eduard B. Yagubskii
Abstract
Abstract Three tetraphenylborates of mononuclear Mn(III) cation complexes with hexadentate ligands, the products of the reaction between a N,N′‐bis(3‐aminopropyl)ethylenediamine and salicylaldehydes with the different haloid substitutions at the 5 or 3,5 positions, have been synthesized: [Mn(5‐F‐sal‐N‐1,5,8,12)]BPh 4 ( 1 ), [Mn(3,5‐diCl‐sal‐N‐1,5,8,12)]BPh 4 ( 2 ) and [Mn(3,5‐Br,Cl‐sal‐N‐1,5,8,12)]BPh 4 ( 3 ). Their crystal structure, dielectric constant (ϵ) and magnetic properties have been studied. Ligand substituents have a dramatic effect on the structure and magnetic properties of the complexes. With decreasing temperature, the complex ( 1 ) shows a gradual spin crossover from the high‐spin state (HS) to the HS:LS intermediate phase, followed by an abrupt transition to the low‐spin state (LS) without changing the crystal symmetry. The complexes 2 and 3 are isostructural, but have fundamentally different properties. Complex 2 demonstrates two structural phase transitions related to sharp spin crossovers from the HS to the HS:LS intermediate phase at 137 K and from the intermediate phase to the LS at 87 K, while complex 3 exhibits only one spin transition from the HS to the HS:LS intermediate phase at 83 K.