High temperature anionic Fe(iii) spin crossover behavior in a mixed-valence Fe(ii)/Fe(iii) complex. Issue 17 (16th April 2021)

• Record Type: Journal Article
• Authors: Ouyang, Zhi-Jian; Mo, Xiao-Ying; Ye, Jia-Qi; Yu, Xiao-Xuan; Huang, Shu-Yuan; Liu, Xiao-Ling; Chen, Wen-Bin; Gao, Song; Dong, Wen
• Is Part Of: Dalton transactions. Volume 50:Issue 17(2021)
• Page Start: 5960
• Page End: 5967
• Publication Date: 2021-04-16
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt00111f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Two ion-pair complexes (PPh4 )[Fe III (HATD)2 ]·2H2 O (1 ) and [Fe II (phen)3 ][Fe III (HATD)2 ]2 ·3DMA·3.5H2 O (2 ) have been synthesized and high temperature Fe(iii ) spin crossover behaviour has been observed in 2 . Abstract : Two ion-pair Fe(iii ) complexes (PPh4 )[Fe III (HATD)2 ]·2H2 O (1, H3 ATD = azotetrazolyl-2, 7-dihydroxynaphthalene) and [Fe II (phen)3 ][Fe III (HATD)2 ]2 ·3DMA·3.5H2 O (2, phen = 1, 10-phenanthroline, DMA = N, N -dimethylformamide) were synthesized by employing the tridentate ligand H3 ATD. Crystal structure analyses reveal that complexes 1 and 2 consist of Fe III ions in an octahedral environment where a Fe III ion is coordinated by two HATD 2− ligands forming the [Fe III (HATD)2 ] − core. The shortest cation⋯anion distance between the phosphorus ion of the (PPh4 ) + cation and the ferric ion of the [Fe III (HATD)2 ] − anion is 13.190 Å in complex 1, whereas that between the ferrous ion of the [Fe II (Phen)3 ] 2+ cation and the ferric ion of the [Fe III (HATD)2 ] − anion is 7.821 Å in complex 2 . C–H⋯C and C–H⋯O hydrogen interactions between the [Fe II (phen)3 ] 2+ cation and the [Fe III (HATD)2 ] − anion are observed in 2 . Face-to-face π-π stacking interactions between naphthalene rings with the separated interplanar center to center distances of 3.421–3.680 Å were observed, which result in a one-dimensional supramolecular chain in complexes 1 and 2 . Magnetic measurements show that complex 1 is in the low-spin (LS) state below 500 K, whereas 2 undergoes a high temperature spin crossover (SCO) between 360 and 500 K. Magneto-structural relationship studies reveal that π-stacking, hydrogen interactions and Coulomb interactions between the [Fe III (HATD)2 ] − anion and the [Fe II (phen)3 ] 2+ cation play a crucial role in the high temperature Fe(iii ) SCO behaviour of complex 2 .