Publication | Open Access
A Brønsted‐Ligand‐Based Iron Complex as a Molecular Switch with Five Accessible States
66
Citations
37
References
2019
Year
A mononuclear Fe<sup>II</sup> complex, prepared with a Brønsted diacid ligand, H<sub>2</sub> L (H<sub>2</sub> L=2-[5-phenyl-1H-pyrazole-3-yl] 6-benzimidazole pyridine), shows switchable physical properties and was isolated in five different electronic states. The spin crossover (SCO) complex, [Fe<sup>II</sup> (H<sub>2</sub> L)<sub>2</sub> ](BF<sub>4</sub> )<sub>2</sub> (1<sub>A</sub> ), exhibits abrupt spin transition at T<sub>1/2</sub> =258 K, and treatment with base yields a deprotonated analogue [Fe<sup>II</sup> (HL)<sub>2</sub> ] (1<sub>B</sub> ), which shows gradual SCO above 350 K. A range of Fe<sup>III</sup> analogues were also characterized. [Fe<sup>III</sup> (HL)(H<sub>2</sub> L)](BF<sub>4</sub> )Cl (1<sub>C</sub> ) has an S=5/2 spin state, while the deprotonated complexes [Fe<sup>III</sup> (L)(HL)], (1<sub>D</sub> ), and (TEA)[Fe<sup>III</sup> (L)<sub>2</sub> ], (1<sub>E</sub> ) exist in the low-spin S=1/2 state. The electronic properties of the five complexes were fully characterized and we demonstrate in situ switching between multiple states in both solution and the solid-state. The versatility of this simple mononuclear system illustrates how proton donor/acceptor ligands can vastly increase the range of accessible states in switchable molecular devices.
| Year | Citations | |
|---|---|---|
Page 1
Page 1