Tuning the electron transfer events in a series of cyanide-bridged [FeCo] squares according to different electron donors

It has been recognized that both the ligand fields and intermolecular interactions may greatly impact the electron-transfer-coupled spin transition (ETCST) events in switchable magnetic materials; however, the engineering of these factors within a given system is still challenging. In this article,...

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Veröffentlicht in:Dalton transactions : an international journal of inorganic chemistry 2022-10, Vol.51 (41), p.15669-15674
Hauptverfasser: Meng, Lingyi, Deng, Yi-Fei, Liu, Jianxun, Liu, Yan Jun, Zhang, Yuan-Zhu
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Sprache:eng
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Zusammenfassung:It has been recognized that both the ligand fields and intermolecular interactions may greatly impact the electron-transfer-coupled spin transition (ETCST) events in switchable magnetic materials; however, the engineering of these factors within a given system is still challenging. In this article, we chose the 4,4′-substituent 2,2′-bipyridine derivatives as chelating ligands according to their increasing electron-donating strength and incremental potential for forming hydrogen bonds (bpy CHO,CH 3 (L1) < bpy CH 2 OH,CH 3 (L2) < bpy CH 2 OH,CH 2 OH (L3)), and prepared three new [Fe 2 Co 2 ] complexes, {[(Tp*)Fe(CN) 3 Co(L) 2 ] 2 [ClO 4 ] 2 }·Sol ( 1 , L = L1, Sol = 4MeCN·2H 2 O; 2 , L = L2, Sol = 3MeCN; 3 , L = L3, Sol = 4MeOH; Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate). X-ray crystallography studies revealed that all the complexes share similar cyanide-bridged [Fe 2 Co 2 ] square compositions except for the different substituted groups of L ligands, which led to the clearly evidenced intercluster hydrogen bonds between the neighbouring hydroxyl groups in 2 and 3 . As a result, 1 remained in the paramagnetic [Fe III,LS 2 Co II,HS 2 ] state over the whole temperature range, while 2 and 3 showed complete ETCST behaviour with the transition temperatures ( T 1/2 ) being 221 and 294 K, respectively. Combined substituent effects and hydrogen-bonding interactions modulate the electron transfer in cyanide bridged [Fe 2 Co 2 ] squares: ferrimagnetism without ETCST for 1 , while complete ETCST with T 1/2 being 221 and 294 K for 2 and 3 , respectively.
ISSN:1477-9226
1477-9234
DOI:10.1039/d2dt02416k