6 Molecular Magnetism of Metal Complexes and Light-Induced …
313
observed, which are assignable as the HS Fe
II and LS Fe
III species. These paramagnetic signals turn into broadening before splitting into two magnetic sextet with
a partially residual paramagnetic components below 7 K. The hyperfine fields were
estimated at 19.2 T for Fe
II and 33.5 T for Fe
III .
6.5 Conclusion
In this chapter, we have focused on the molecular magnetism and its related lightinduced phase transitions from the viewpoint of Mössbauer spectroscopy. In the
Sect. 6.2, we have described mainly the dynamic spin equilibrium phenomena for
[M
II Fe
III (mto) 3 ] (M = Zn, Mn) complexes. In the case of (C 6 H 5 ) 4 P[Mn
II Fe
III (mto) 3 ]
consisting of Fe
III O 3 S 3 and Mn
II O 6 octahedra, there exists a rapid spin equilibrium (τ < 10
−7 s) between the HS and LS states at the Fe
III O 3 S 3 site, which
induces the fluctuation of internal magnetic field on the Mn
II site. Owing to
the fluctuation of internal magnetic field caused by the rapid spin equilibrium,
(C 6 H 5 ) 4 P[Mn
II Fe
III (mto) 3 ] undergoes the successive magnetic phase transitions at
30 and 23 K. In the Sect. 6.3, we have described the CTPT and the ferromagnetism of
(n-C n H 2n+1 ) 4 N[Fe
II Fe
III (dto) 3 ]. At the CTPT, the electrons of Avogadro’s constant
transfer between the Fe
II and Fe
III sites, and the Fe valence state is dynamically
fluctuated with a frequency of about 0.1 MHz, which was confirmed by means of
μSR. In order to control the ferromagnetism and the CTPT by means of photoirradiation, we have synthesized a photo-responsive organic-inorganic hybrid system,
(SP-Me)[Fe
II Fe
III (dto) 3 ], and discovered that the photo-isomerization of intercalated
SP-Me by UV light irradiation induces the CTPT and the enhancement of the Curie
temperature from 7 to 22 K. In the Sect. 6.4, we have described the spin dynamics
of various kinds of molecular magnets such as SMMs with transition-metal clusters,
SIMs with linear coordination, and SCMs with easy-plane anisotropy.
Acknowledgements In this chapter, our contributed original research has been created in collaboration with Profs. M. Enomoto (Tokyo University of Science), M. Itoi (Nihon University), M. Okubo
(The University of Tokyo), K. Kagesawa (Tohoku University), T. Matsuo (Kinki University), Y.
Kobayashi (University of Electro-Communications), T. Kajiwara (Nara Women’s University), K.
Tamao (Toyota Riken), M. Yamashita (Tohoku University), M. Seto (Kyoto University), H. Sawa
(Nagoya University), E. Nishibori (Tsukuba University), Drs. N. Kida (Mitsubishi Chemical Co.),
Y. Ono (Mitsubishi Chemical Co.), I. Watanabe (RIKEN). We wish to thank all the collaborators.
This work has partly been supported by Toyota Physical and Chemical Research Institute, and a
Grant-in-Aid for Science Research from the Ministry of Education, Science, Sports and culture.
313
observed, which are assignable as the HS Fe
II and LS Fe
III species. These paramagnetic signals turn into broadening before splitting into two magnetic sextet with
a partially residual paramagnetic components below 7 K. The hyperfine fields were
estimated at 19.2 T for Fe
II and 33.5 T for Fe
III .
6.5 Conclusion
In this chapter, we have focused on the molecular magnetism and its related lightinduced phase transitions from the viewpoint of Mössbauer spectroscopy. In the
Sect. 6.2, we have described mainly the dynamic spin equilibrium phenomena for
[M
II Fe
III (mto) 3 ] (M = Zn, Mn) complexes. In the case of (C 6 H 5 ) 4 P[Mn
II Fe
III (mto) 3 ]
consisting of Fe
III O 3 S 3 and Mn
II O 6 octahedra, there exists a rapid spin equilibrium (τ < 10
−7 s) between the HS and LS states at the Fe
III O 3 S 3 site, which
induces the fluctuation of internal magnetic field on the Mn
II site. Owing to
the fluctuation of internal magnetic field caused by the rapid spin equilibrium,
(C 6 H 5 ) 4 P[Mn
II Fe
III (mto) 3 ] undergoes the successive magnetic phase transitions at
30 and 23 K. In the Sect. 6.3, we have described the CTPT and the ferromagnetism of
(n-C n H 2n+1 ) 4 N[Fe
II Fe
III (dto) 3 ]. At the CTPT, the electrons of Avogadro’s constant
transfer between the Fe
II and Fe
III sites, and the Fe valence state is dynamically
fluctuated with a frequency of about 0.1 MHz, which was confirmed by means of
μSR. In order to control the ferromagnetism and the CTPT by means of photoirradiation, we have synthesized a photo-responsive organic-inorganic hybrid system,
(SP-Me)[Fe
II Fe
III (dto) 3 ], and discovered that the photo-isomerization of intercalated
SP-Me by UV light irradiation induces the CTPT and the enhancement of the Curie
temperature from 7 to 22 K. In the Sect. 6.4, we have described the spin dynamics
of various kinds of molecular magnets such as SMMs with transition-metal clusters,
SIMs with linear coordination, and SCMs with easy-plane anisotropy.
Acknowledgements In this chapter, our contributed original research has been created in collaboration with Profs. M. Enomoto (Tokyo University of Science), M. Itoi (Nihon University), M. Okubo
(The University of Tokyo), K. Kagesawa (Tohoku University), T. Matsuo (Kinki University), Y.
Kobayashi (University of Electro-Communications), T. Kajiwara (Nara Women’s University), K.
Tamao (Toyota Riken), M. Yamashita (Tohoku University), M. Seto (Kyoto University), H. Sawa
(Nagoya University), E. Nishibori (Tsukuba University), Drs. N. Kida (Mitsubishi Chemical Co.),
Y. Ono (Mitsubishi Chemical Co.), I. Watanabe (RIKEN). We wish to thank all the collaborators.
This work has partly been supported by Toyota Physical and Chemical Research Institute, and a
Grant-in-Aid for Science Research from the Ministry of Education, Science, Sports and culture.