In air a spin crossover active iron(ii) complex of amine/NCBH3− ligands is converted to a low spin complex of imine/CN− ligands. Issue 47 (9th November 2015)

• Record Type: Journal Article
• Authors: Zhou, Jian; Zhu, Bo-Wen; Luan, Jie; Liu, Zhan; Fang, Jing-Kun; Bao, Xin; Peng, Guo; Tucek, Jiri; Bao, Song-Song; Zheng, Li-Min
• Is Part Of: Dalton transactions. Volume 44:Issue 47(2015)
• Page Start: 20551
• Page End: 20561
• Publication Date: 2015-11-09
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c5dt03464g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A spin crossover Fe II complex is in situ converted to a low spin complex in the presence of air, induced by the oxidative dehydrogenation of the tetradentate ligand and the generation of CN − from NCBH3 − . Abstract : Two new mononuclear Fe II complexes, [FeL1 (NCBH3 )2 ] (1 ) and [FeL2 (CN)2 ]·3H2 O (2 ) (L1 = N, N ′-bis(2-pyridylmethyl)-1, 2-ethanediamine, L2 = N -(2-pyridylmethyl)- N ′-(2-pyridylmethylene)-1, 2-ethanediamine) were synthesized from the same starting solution under different atmospheric conditions. Complex1 was isolated under an N2 atmosphere with an expected molecular structure, namely a tetradentate L1 ligand and two NCBH3 − co-ligands wrapping an iron(ii ) ion. It exhibits a gradual spin crossover centered around 355 K, as confirmed by X-ray crystallography, magnetic, DSC and Mössbauer studies. Complex2 was isolated in the presence of air. One of the secondary amine groups in L1 undergoes an in situ oxidative dehydrogenation, forming a new monoimine asymmetric ligand L2 . Besides, a CN − co-ligand is also in situ generated from NCBH3 − during the reaction. The strong ligand field strength imposed by CN − and L2 stabilizes2 in the LS state. Solvent water molecules in complex2 are hydrogen bonded into a well-defined 1D water chain.2 shows a proton conductivity of 8.9 × 10 −5 S cm −1 at 55 °C and 95% relative humidity.