Abstract
Mononuclear [Fe(H2LR)2]2+ and dinuclear [Fe2(H2LR)3]4+ (R = H, 2-Me, 5-Me) complexes containing the new imidazole-4-carbaldehyde azine ligand (H2LH) and its derivatives (H2L 2-Me and H2L5-Me) prepared from the condensation reaction of 4-formylimidazole or 2-methyl- or 5-methyl-4- formylimidazole with hydrazine (2:1) were prepared, and their magnetostructural relationships were studied. In the mononuclear complexes, H2L R acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H2LR acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate. At room temperature, [Fe2(H 2LH)3](CIO4)4 and [Fe2(H2L2-Me)3](ClO 4)4 were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H2L with electron-donating methyl groups being stronger than H 2LH, with the order of the ligand field strengths being H2L2-Me > H2LH. However, in the mononuclear [Fe(H2LH)2](ClO4) 2 and [Fe(H2L2-Me)2](ClO 4)2 complexes, a different order of ligand field strengths, H 2LH > H2L2-Me, was observed because [Fe(H2LH)2](ClO4) 2 was in the LS state while [Fe(H2L2-M) 2](ClO4)2 was in the HS state at room temperature. X-ray structural studies revealed that the interligand steric repulsion between a methyl group of an H2L2-Me ligand and the other ligand in [Fe(H2L2-Me)2](ClO 4)2 is responsible for the observed change in the spin state. Two kinds of crystals, needles and blocks, were isolated for [Fe 2(H2LH)3](BF4) 4, and both exhibited a sharp spin transition, [LS-HS] [HS-HS]. The spin transition of the block crystals is more abrupt with a hysteresis, T c↑ = 190 K and Tc↓ = 183 K withΔT= 7 K.
| Original language | English |
|---|---|
| Pages (from-to) | 8784-8795 |
| Number of pages | 12 |
| Journal | Inorganic Chemistry |
| Volume | 48 |
| Issue number | 18 |
| DOIs | |
| Publication status | Published - Sep 21 2009 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Physical and Theoretical Chemistry
Cite this
Structures and spin states of bist (tridentate)-type mononuclear and triple helicate dinuclear Iron(II) complexes of Lmidazole-4-carbaldehyde azine. / Sunatsuki, Yukinari; Kawamoto, Ryohei; Fujita, Kunihiro; Maruyama, Hisashi; Suzuki, Takayoshi; Ishida, Hiroyuki; Kojima, Masaaki; Iijima, Seiichiro; Matsumoto, Naohide.
In: Inorganic Chemistry, Vol. 48, No. 18, 21.09.2009, p. 8784-8795.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structures and spin states of bist (tridentate)-type mononuclear and triple helicate dinuclear Iron(II) complexes of Lmidazole-4-carbaldehyde azine
AU - Sunatsuki, Yukinari
AU - Kawamoto, Ryohei
AU - Fujita, Kunihiro
AU - Maruyama, Hisashi
AU - Suzuki, Takayoshi
AU - Ishida, Hiroyuki
AU - Kojima, Masaaki
AU - Iijima, Seiichiro
AU - Matsumoto, Naohide
PY - 2009/9/21
Y1 - 2009/9/21
N2 - Mononuclear [Fe(H2LR)2]2+ and dinuclear [Fe2(H2LR)3]4+ (R = H, 2-Me, 5-Me) complexes containing the new imidazole-4-carbaldehyde azine ligand (H2LH) and its derivatives (H2L 2-Me and H2L5-Me) prepared from the condensation reaction of 4-formylimidazole or 2-methyl- or 5-methyl-4- formylimidazole with hydrazine (2:1) were prepared, and their magnetostructural relationships were studied. In the mononuclear complexes, H2L R acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H2LR acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate. At room temperature, [Fe2(H 2LH)3](CIO4)4 and [Fe2(H2L2-Me)3](ClO 4)4 were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H2L with electron-donating methyl groups being stronger than H 2LH, with the order of the ligand field strengths being H2L2-Me > H2LH. However, in the mononuclear [Fe(H2LH)2](ClO4) 2 and [Fe(H2L2-Me)2](ClO 4)2 complexes, a different order of ligand field strengths, H 2LH > H2L2-Me, was observed because [Fe(H2LH)2](ClO4) 2 was in the LS state while [Fe(H2L2-M) 2](ClO4)2 was in the HS state at room temperature. X-ray structural studies revealed that the interligand steric repulsion between a methyl group of an H2L2-Me ligand and the other ligand in [Fe(H2L2-Me)2](ClO 4)2 is responsible for the observed change in the spin state. Two kinds of crystals, needles and blocks, were isolated for [Fe 2(H2LH)3](BF4) 4, and both exhibited a sharp spin transition, [LS-HS] [HS-HS]. The spin transition of the block crystals is more abrupt with a hysteresis, T c↑ = 190 K and Tc↓ = 183 K withΔT= 7 K.
AB - Mononuclear [Fe(H2LR)2]2+ and dinuclear [Fe2(H2LR)3]4+ (R = H, 2-Me, 5-Me) complexes containing the new imidazole-4-carbaldehyde azine ligand (H2LH) and its derivatives (H2L 2-Me and H2L5-Me) prepared from the condensation reaction of 4-formylimidazole or 2-methyl- or 5-methyl-4- formylimidazole with hydrazine (2:1) were prepared, and their magnetostructural relationships were studied. In the mononuclear complexes, H2L R acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H2LR acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate. At room temperature, [Fe2(H 2LH)3](CIO4)4 and [Fe2(H2L2-Me)3](ClO 4)4 were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H2L with electron-donating methyl groups being stronger than H 2LH, with the order of the ligand field strengths being H2L2-Me > H2LH. However, in the mononuclear [Fe(H2LH)2](ClO4) 2 and [Fe(H2L2-Me)2](ClO 4)2 complexes, a different order of ligand field strengths, H 2LH > H2L2-Me, was observed because [Fe(H2LH)2](ClO4) 2 was in the LS state while [Fe(H2L2-M) 2](ClO4)2 was in the HS state at room temperature. X-ray structural studies revealed that the interligand steric repulsion between a methyl group of an H2L2-Me ligand and the other ligand in [Fe(H2L2-Me)2](ClO 4)2 is responsible for the observed change in the spin state. Two kinds of crystals, needles and blocks, were isolated for [Fe 2(H2LH)3](BF4) 4, and both exhibited a sharp spin transition, [LS-HS] [HS-HS]. The spin transition of the block crystals is more abrupt with a hysteresis, T c↑ = 190 K and Tc↓ = 183 K withΔT= 7 K.
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U2 - 10.1021/ic900977m
DO - 10.1021/ic900977m
M3 - Article
VL - 48
SP - 8784
EP - 8795
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 18
ER -