Study on physical properties of cyano-bridged copper-tungsten bimetallic assemblies

学位の種別:課程博士University of Tokyo(東京大学

Tetra­potassium hepta­cyanido­molybdate(III) dihydrate

The asymmetric unit of the title compound, KI 4[MoIII(CN)7]·2H2O, consists of one [Mo(CN)7]4− anion, four K+ cations, and two water mol­ecules. The [MoIII(CN)7]4− anion has a seven-coordinated capped-trigonal-prismatic coordination geometry. The site-occupancy factors of the disordered water mol­ecules were set at 0.90, 0.60 and 0.50. The H-atom positions could not be determined for two of the water mol­ecules. The H atoms of the water with a site-occupancy factor of 0.90 were refined using O—H and H⋯H distance restraints

Poly[[diaqua­deca-μ-cyanido-hexa­cyanidobis­(4-cyano­pyridine)di-μ-pyrimidine-tricopper(II)ditungsten(V)] dihydrate]

In the polymeric title compound, {[Cu3W2(CN)16(C4H4N2)2(C6H4N2)2(H2O)2]·2H2O}n, the coordination geometry of W is an eight-coordinated bicapped trigonal prism. Five of the CN groups of [W(CN)8] are bridged to Cu ions. The coordination geometries of the Cu atoms are each pseudo-octa­hedral; one Cu atom is located on a centre of inversion. The cyano-bridged W–Cu layers are linked by Cu-containing pillars, to form a three-dimensional network with cavities occupied by noncoordinated water and 4-cyano­pyridine mol­ecules

Poly[[diaquadeca-μ2-cyanido-κ20C:N-hexacyanido-κ6C-bis(μ2-5-methylpyrimidine-κ2N:N′)bis(5-methylpyrimidine-κN)tricopper(II)ditungstate(V)] dihydrate]

In the title complex, {[Cu3[W(CN)8]2(C5H6N2)4(H2O)2]·2H2O}n, the coordination polyhedron of the eight-coordinated WV atom is a bicapped trigonal prism, in which five CN groups are bridged to CuII ions, and the other three CN groups are terminally bound. Two of the CuII ions lie on a centre of inversion and each of the three independent CuII cations is pseudo-octahedrally coordinated. In the crystal structure, cyanido-bridged-Cu—W—Cu layers are linked by pillars involving the third independent CuII ion, generating a three-dimensional network with non-coordinating water molecules and 5-methylpyrimidine molecules. O—H...O and O—H...N hydrogen bonds involve the coordinating and non-coordinating water molecules, the CN groups and the 5-methylpyrimidine molecules

High Thermal Durability of Water-Free Copper-Octacyanotungsten-Based Magnets Containing Halogen Bonds

Two-dimensional (2-D) cyano-bridged Cu–W bimetallic assemblies that include halogen-substituted pyridine molecules, [Cu^II(3-iodopyridine)₄][Cu^II(3-iodopyridine)₂]₂[W^V(CN)₈]₂ (<b>1</b>) (triclinic crystal structure, <i>P</i>1̅ space group), [Cu^II(3-bromopyridine)₄][Cu^II(3-bromopyridine)₂]₂[W^V(CN)₈]₂ (<b>2</b>) (triclinic, <i>P</i>1̅), and [Cu^II(3-chloropyridine)₂(H₂O)₂][Cu^II(3-chloropyridine)₂]₂[W^V(CN)₈]₂·4H₂O (<b>3</b>) (monoclinic, <i>P</i>2₁/<i>c</i>), were synthesized. Thermogravimetric measurements demonstrate that <b>1</b> and <b>2</b> have high thermal durability up to ca. 150 °C (423 K) due to the lack of water molecules in the crystal and the stacked Cu–W 2-D layers with halogen bonding between halogen-substituted pyridine and the cyano nitrogen of octacyanotungstate. In contrast, <b>3</b> exhibits weight loss above ca. 50 °C (323 K) as the water molecules between the 2-D layers are removed upon heating. Magnetic measurements show that <b>1</b>–<b>3</b> are ferromagnets due to parallel ordering of the magnetic spins on Cu^II (<i>S</i> = 1/2) and W^V (<i>S</i> = 1/2) with Curie temperatures (<i>T</i>_C) of 4.7 K (<b>1</b>), 5.2 K (<b>2</b>), and 7.2 K (<b>3</b>)

Spectroscopic and Magnetic Properties of the Metastable States in the Coordination Network [{Co(prm)(2)}(2){Co(H(2)O)(2)}{W(CN)(8)}(2)]*4H(2)O (prm = pyrimidine).

The study of the metastable states, obtained by thermal quenching or by light irradiation in the [{Co(prm)(2)}(2){Co(H(2)O)(2)}{W(CN)(8)}(2)]*4H(2)O complex, is reported using powder X-ray diffraction, Raman spectroscopy, optical reflectivity, and magnetic measurements. This compound is characterized by a electron-transfer (ET) phase transition occurring between a high-temperature phase (HT phase) formed by paramagnetic Co(II)-W(V) units and a low-temperature phase (LT phase) formed by diamagnetic Co(III)-W(IV) units. Metastable phases can be induced at low temperature either by thermal quenching rapidly cooling phase named RC or by irradiation photo-induced phase named PI similar to the well-known Light-Induced Excited Spin State Trapping effect. The relaxation dynamics of the metastable phases have been studied and revealed some differences between the RC and PI phases. The sigmoidal shape of the relaxation curves in the RC phase is in agreement with the cooperative nature of the process. Thermodynamic parameters that govern the relaxation have been determined and used to reproduce the experimental Thermal-Induced Excited Spin State Trapping curve