TY - JOUR
T1 - Photo-induced spin transition of iron(III) compounds with π-π intermolecular interactions
AU - Hayami, Shinya
AU - Hiki, Kenji
AU - Kawahara, Takayoshi
AU - Maeda, Yonezo
AU - Urakami, Daisuke
AU - Inoue, Katsuya
AU - Ohama, Mitsuo
AU - Kawata, Satoshi
AU - Sato, Osamu
PY - 2009/3/23
Y1 - 2009/3/23
N2 - Iron(III) spin-crossover compounds [Fe(pap)2]ClO4 (1), [Fe-(pap)2]BF4 (2), [Fe(pap)2]PF 6 (3), [Fe-(qsal)2]NCS (4), and [Fe(qsal)2]NCSe (5) (Hpap = 2-(2-pyridylmethyleneamino)phenol and Hqsal = 2-[(8- quinolinylimino)methyl]phenol) were prepared and their spin-transition properties investigated by magnetic susceptibility and Mössbauer spectroscopy measurements. The iron(III) compounds exhibited spin transition with thermal hysteresis. Single crystals of the iron(III) compounds were obtained as suitable solvent adducts for X-ray analysis, and structures in high-spin (HS) and low-spin (LS) states were revealed. Light-induced excited-spin-state trapping (LIESST) effects of the iron(III) compounds were induced by light irradiation at 532 nm for 1-3 and at 800 nm for 4 and 5. The activation energy Ea and the low-temperature tunneling rate k HL(T→0) of iron(III) LIESST compound 1 were estimated to be 1079 cm-1 and 2.4×10-8 S-1, respectively, by HS→LS relaxation experiments. The Huang-Rhys factor S of 1 was also estimated to be 50, which was similar to that expected for iron(II) complexes. It is thought that the slow relaxation in iron(III) systems is achieved by the large structural distortion between HS and LS states. Introduction of strong intermolecular interactions, such as π-π stacking, can also play an important role in the relaxation behavior, because it can enhance the structural distortion of the LIESST complex.
AB - Iron(III) spin-crossover compounds [Fe(pap)2]ClO4 (1), [Fe-(pap)2]BF4 (2), [Fe(pap)2]PF 6 (3), [Fe-(qsal)2]NCS (4), and [Fe(qsal)2]NCSe (5) (Hpap = 2-(2-pyridylmethyleneamino)phenol and Hqsal = 2-[(8- quinolinylimino)methyl]phenol) were prepared and their spin-transition properties investigated by magnetic susceptibility and Mössbauer spectroscopy measurements. The iron(III) compounds exhibited spin transition with thermal hysteresis. Single crystals of the iron(III) compounds were obtained as suitable solvent adducts for X-ray analysis, and structures in high-spin (HS) and low-spin (LS) states were revealed. Light-induced excited-spin-state trapping (LIESST) effects of the iron(III) compounds were induced by light irradiation at 532 nm for 1-3 and at 800 nm for 4 and 5. The activation energy Ea and the low-temperature tunneling rate k HL(T→0) of iron(III) LIESST compound 1 were estimated to be 1079 cm-1 and 2.4×10-8 S-1, respectively, by HS→LS relaxation experiments. The Huang-Rhys factor S of 1 was also estimated to be 50, which was similar to that expected for iron(II) complexes. It is thought that the slow relaxation in iron(III) systems is achieved by the large structural distortion between HS and LS states. Introduction of strong intermolecular interactions, such as π-π stacking, can also play an important role in the relaxation behavior, because it can enhance the structural distortion of the LIESST complex.
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U2 - 10.1002/chem.200802395
DO - 10.1002/chem.200802395
M3 - Article
C2 - 19191246
AN - SCOPUS:63749117276
SN - 0947-6539
VL - 15
SP - 3497
EP - 3508
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 14
ER -