Wydział Chemii

Maria Książek

Marek Weselski

Joachim Kusz

Robert Bronisz

2022

Dalton Transactions

51

958-968

10.1039/d1dt03578a

Naukowa

Angielski

Artykuł

1,4-di(1,2,3-triazol-1-yl)butane (bbtr) forms two-dimensional (2D) coordination polymer (1) in the reaction with iron(II) triflate. In the crystal lattice there are two crystallographically unique iron(II) ions surrounded octahedrally by 1,2,3-triazole ring coordinated through nitrogen atoms N3. Single crystal X-ray diffraction studies revealed that spin crossover for each crystallographically independent iron(II) ions proceeds at different temperatures (T_1/2(Fe1) = 201 K; T_1/2(Fe2) = 216 K), while the magnetic measurements showed that there is one step, complete thermally induced spin crossover (T_1/2 = 205 K). The complex 1 undergoes, with time, single crystal-to-single crystal transformation (SCSC) to the converted system (1c) from R-3 to P6₃ space group, accompanied by significant changes of the lattice parameters c (shortening of approx. 1/3) and consequently unit cell volume. Structural transformation is associated with rebuilding polymeric layer as well as anions network which is reflected in results of Mössbauer studies. In polymorphic system (1c) there are three crystallographically independent iron(II) ions. Results of temperature dependence of magnetic susceptibility indicated complete, one step spin crossover very similar to 1, however, single crystal X-ray diffraction studies of 1c revealed that spin crossover for each crystallographically independent iron(II) ions occurs in different manner revealing three elementary stages (T_1/2(Fe1) = 200 K; T_1/2(Fe2) = 212 K, T_1/2(Fe3) = 214 K).

http://dx.doi.org/10.1039/D1DT03578A

https://www.rsc.org/