Four‐Step Spin Crossover in a New Cyano‐Bridged Iron‐Silver Coordination Polymer

• Published in: Chemistry : a European journal 2022-08, Vol.28 (44), p.e202200924-n/a
• Main Authors: Kucheriv, Olesia I., Shylin, Sergii I., Sirenko, Valerii Y., Ksenofontov, Vadim, Tremel, Wolfgang, Dascălu, Ioan‐Andrei, Shova, Sergiu, Gural'skiy, Il'ya A.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry with specialization in Inorganic Chemistry; Coordination polymers; Crystal structure; Crystallography; Data storage; Hofmann clathrates analogues; Iron; iron(II); Kemi med inriktning mot oorganisk kemi; magnetism; multistep transitions; Polymers; Silver; spin crossover; spin state; Spin transition; substituted pyrazine; Switches
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202200924

Spin‐crossover complexes with multistep transitions attract much attention due to their potential applications as multi‐switches and for data storage. A four‐step spin crossover is observed in the new iron(II)‐based cyanometallic guest‐free framework compound Fe(2‐ethoxypyrazine)2{Ag(CN)2}2 during the transition from the low‐spin to the high‐spin state. A reverse process occurs in three steps. Crystallographic studies reveal an associated stepwise evolution of the crystal structures. Multiple transitions in the reported complex originate from distinct FeII sites which exist due to the packing of the ligand with a bulky substituent. A new guest‐free Hofmann clathrate analogue Fe(2‐ethoxypyrazine)2{Ag(CN)2}2 which undergoes a four‐step spin crossover during the transition from the low‐spin to the high‐spin state is reported. At the first step 1/3 of centers become high spin, at the second step another 1/3 of centres become high spin, at the third step spin mixed crystallographic centres are observed, and after the fourth step all centers are high spin.