Wydział Chemii

Aleksandra Tołoczko

Marcin Kaźmierczak

Marek Weselski

Miłosz Siczek

Maria Książek

Joachim Kusz

Robert Bronisz

2023

Crystal Growth and Design

23

1611-1621

10.1021/acs.cgd.2c01238

Naukowa

Angielski

Artykuł

The reaction between 1,1′-di(tetrazol-1-ylo)methane (1ditz) and iron(II) tetrafluoroborate carried out in the presence of adiponitrile (ADN) afforded the coordination compound [Fe₂(μ-1ditz)₄(μ-ADN)(ADN)₂](BF₄)₄·2ADN. The 1ditz molecules bridge the Fe(II) ions in two directions, resulting in a polymeric layer, whereas adiponitrile molecules join 1ditz-based units, extending the structure into the three-dimensional network. One of the two axial coordination sites of Fe(II) is occupied by monodentately coordinating adiponitrile. Dinitrile can also act as guest molecules occupying the area between the 1ditz-based layers. Cooling from room temperature triggers the structural phase transitions HS(P1; a, b, c) → HS(P2; 2a, b, c) → LS(P3; a, b, c) (P, phase; HS, high spin; and LS, low spin) associated with the conformational changes of the adiponitrile molecules. In the cooling mode, T_1/2^↓ = 160 K, while in the heating mode T_1/2^↑ is equal to 185 K. Depending on the further path of change of the temperature, it is possible (i) to perform the same cooling/heating cycle (T_1/2^↓ = 160 K; T_1/2^↑ = 185 K) after the sample is reheated above 240 K or (ii) to execute the cooling with T_1/2^↓ = 167 K after the heating is stopped at 190 K, where the phase with superlattice (P2) does not appear. Both ways are reversible, and they are managed by conformational changes of the adiponitrile molecules.

http://dx.doi.org/10.1021/acs.cgd.2c01238

https://www.acs.org/content/acs/en.html