2003 | OriginalPaper | Chapter
Polymorphism and Pressure Driven Thermal Spin Crossover Phenomenon in [Fe(abpt)2(NCX)2] (X=S, and Se): Synthesis,Structure and Magnetic Properties
Authors : Ana B. Gaspar, M. Carmen Muñoz, Nicolás Moliner, Vadim Ksenofontov, Georgii Levchenko, Philipp Gütlich, José Antonio Reall
Published in: Molecular Magnets Recent Highlights
Publisher: Springer Vienna
Included in: Professional Book Archive
Activate our intelligent search to find suitable subject content or patents.
Select sections of text to find matching patents with Artificial Intelligence. powered by
Select sections of text to find additional relevant content using AI-assisted search. powered by
The monomeric compounds [Fe(abpt2(NCX)2(X = S (1), Se (2) and abpt = 4-amino- 3,5-bis(pyridin-2-yl)-1,2,4-triazole) have been synthesized and characterized. They crystallize in the monoclinic P21/n space group with a = 11.637(2) Å, b = 9.8021(14) Å, c = 12.9838(12) Å, β = 101.126(14)°, and Z=2 for 1, and a= 11.601(2) Å, b = 9.6666(14) Å, c = 12.883(2) Å, β = 101.449(10)°, and Z = 2 for 2. The unit cell contains a pair mononuclear [Fe(abpt)2(NCX)21 units related by a center of symmetry. Each iron atom, located at a molecular inversion center, is in a distorted octahedral environment. Four of the six nitrogen atoms coordinated to the Fe(II) ion belong to the pyridine-N(1) and triazole-N(2) rings of two abpt ligands. The remaining trans positions are occupied by two nitrogen atoms, N(3), belonging to the two pseudo-halide ligands. The magnetic susceptibility measurements at ambient pressure have revealed that they are in the high-spin range in the 2 K300 K temperature range. The pressure study has revealed that compound 1 remains in high-spin as pressure is increased up to 4.4kbar, where an incomplete thermal spin crossover appears at around T1/2 = 65 K.. Quenching experiments at 4.4 kbar have shown that the incomplete character of the conversion is a consequence of slow kinetics. Relatively sharp spin transition takes place at T1/2 = 106, 152 and 179 K, as pressure attains 5.6, 8.6 and 10.5 kbar, respectively.