Photoinduced Magnetization in Copper Octacyanomolybdate

Abstract

This article describes the studies of a photomagnetic cyanide-bridged Cu-Mo bimetallic assembly, Cu(II)(2)[Mo(IV)(CN)(8)].8H(2)O (Cu(II), S = (1)/(2); Mo(IV), S = 0) (1), which has an intervalence transfer (IT) band from Mo(IV)-CN-Cu(II) to Mo(V)-CN-Cu(I) around 480 nm. Wide-angle X-ray scattering and X-ray spectroscopic studies provide precise information about the 3D connectivity and the local environment of the transition metal ions. Irradiating with blue light causes solid 1 to exhibit a spontaneous magnetization (Curie temperature = 25 K). The thermal reversibility is carefully studied and shows the long-time stability of the photoinduced state up to 100 K. Photoreversibility is also observed; i.e., the magnetization is induced by irradiation with light below 520 nm, while the magnetization is reduced by irradiation with light above 520 nm. The UV-vis absorption spectrum after irradiation shows a decrease of the IT band and the appearance of the reverse-IT band in the region of 600-900 nm (lambda(max) = 710 nm). This UV-vis absorption spectrum is recovered to the original spectrum by irradiation with 658-, 785-, and 840-nm light. In this photomagnetic effect, the excitation of the IT band causes an electron transfer from Mo(IV) to Cu(II), producing a ferromagnetic mixed-valence isomer of Cu(I)Cu(II)[Mo(V)(CN)(8)].8H(2)O (Cu(I), S = 0; Cu(II), S = (1)/(2); Mo(V), S = (1)/(2)) (1'). 1' returns to 1 by irradiation of the reverse-IT band, which obeys the scheme for the potential energy surface in mixed-valence class II compounds.

Long‐Range Magnetic Ordering in a TbIII–MoV Cyanido‐Bridged Quasi‐One‐Dimensional Complex

“…[4][5][6][7][8] More recently, [M(CN) 8 ] 3À/4À (M = Mo, W) anions have become attractive building blocks for the synthesis of new cyanido-bridged networks with remarkable magnetic and photomagnetic properties. [9][10][11] Octacyanidometallates profit from the enhanced p backbonding and superexchange efficiency resulting from the greater diffuseness and radial distribution of 4d/5d orbitals as compared with 3d orbitals. Therefore, the combination of the anionic octacyanidometallate building blocks with rare earth metal ions that have strong spin-orbit coupling is a challenging route towards new supramolecular magnetic materials with intrinsic anisotropy.…”

“…The development of such materials has been somewhat hampered by the tendency of the rare earth metal ions to adopt high coordination numbers and their ability to easily adapt to a given environment. [7,[12][13][14][15] (10) .…”

“…A systematic study of this system varying the type of rare earth metal ion and also replacing Mo V by W V is in progress. (10), c = 14.252(2) , V = 3140.9 (7) 3 , 1 calcd = 1.8365(4) g cm À3 , Z = 4, m-(Mo Ka ) = 2.696 mm À1 , T = 150 K, 65 176 reflections, 7189 of which were unique (R int = 0.0816). The structure was solved by Patterson methods using DIRDIF and was refined on F 2 by least-squares procedures using SHELXL-97.…”

Thermally-Accessible Lattice Strain and Local Pseudo Jahn-Teller Distortion in Various Dimensional CuII-MIII Bimetallic Cyanide-Bridged Assemblies

“…Two-dimensional zigzag networks of interchain cyanide-bridges of -Fe1-CN-Cu1-NC-Fe2-running in the ac plane and long cyanide-bridging chains of -Fe2-CN-Cu2-NC-Fe2-along the crystallographic a axis are formed in the crystals. Irrespective of bridging cyanides or terminal ones, no remarkable deviation is observed in structural features about cyanides [35][36][37][38][39][40][41], and cis-C-M-C and trans-C-M-C bond angles are close to 90˚ and 180˚, respectively. Indeed, the structures of coordinating cyanides are in agreement with that of being involved bybackdonation from the filled d orbitals of metals to the empty * orbitals of cyanides.…”

Metal Substitution Effect on a Three-Dimensional Cyanido-Bridged Fe Spin-Crossover Network

“…In the field of molecule-based magnets [26][27][28][29][30], cyanido-bridged metal assemblies have drawn attention because they exhibit various magnetic functionalities such as a high Curie temperature (T c ) [31][32][33][34], a charge transfer transition [35][36][37][38][39][40][41][42], and an externally stimulated phase transition phenomena [43][44][45][46][47]. In the recent years, we have synthesized several kinds of magnetic cyanido-bridged bimetal assemblies possessing Fe spin-crossover sites.…”