Haruhiko Yokoyama

Synthesis of novel copper (II) benzoate pyrazine and its phase transition induced by CO 2 adsorption

Abstract A novel crystalline solid, [Cu(II)2(O2CPh)4(pyz)]n, was synthesized and characterized by single-crystal X-ray diffraction analysis; the compound demonstrates thermal phase transition that is correlated with CO2 adsorption.

On the anomalous concentration dependence of the inner-sphere hydration number change of aqua lanthanide ions

Contrary to the expectation from the simple equilibrium reaction: where Ln3+ is a lanthanide ion, nona-aqua Ln3+ species anomalously increase in population with a decrease in water content in aqueous europium and gadolinium chloride solutions. From the enormous data reported by Spedding et al. (Chem. Eng. Data 1975, 20, 72), the anomalous behaviour is shown to be a general phenomenon in aqueous lanthanide chloride and perchlorate solutions at all concentration ranges. It is concluded from the Raman experiment that the involvement of the outer-sphere complex formations in the equilibrium reaction for hydration number change is the main cause for the anomalous behaviour.

Structure of solvated metal ions in nitrate and chloride solutions of erbium(III) and yttrium(III) in dimethyl sulfoxide

X-ray diffraction measurements on 1M yttrium(III) and erbium(III) nitrate and chloride solutions in dimethyl sulfoxide (DMSO) have shown that Er(III) and Y(III) solutions of equal compositions are isostructural. The intensity difference functions can then be used to derive the detailed structure of the coordination sphere around the metal ions. The DMSO molecules are coordinated over oxygen with average M-O-S bond angles of about 130°. Two different conformations, corresponding to different relative orientations of the M-O and O-S bonds, seem to be prevalent. In the nitrate solutions an average of about 1.5 nitrate ions are coordinated as bidentate ligands to each metal ion. In the chloride solutions about 1.3 chloride ions belong to the inner-coordination sphere.

Hydrophobic Hydration Structures of Tris(1, 10-phenanthroline)metal and Tris(2, 2'-bipyridine)metal Complex Ions and Effect of the Ionic Charge. X-Ray Diffraction Study with Isomorphous Substitution

X-Ray diffraction measurements have been made for aqueous solutions of sulfates or chlorides of [Ru(phen)3]2+, [Ni(phen)3]2+, [Ru(bpy)3]2+, [Ni(bpy)3]2+, [Rh(bpy)3]3+, and [Cr(bpy)3]3+ (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine). Radial distribution functions for the metal interactions were obtained by the isomorphous substitution between ruthenium(II) and nickel(II) complexes or between rhodium(III) and chromium(III) complexes. Metal–nitrogen and metal–carbon distances within the complex ions in solution were essentially in agreement with those in the crystals. Regarding the divalent metal complexes, about two water molecules seemed to exist at a distance of 3.5—3.6 A (1 A = 10−10 m) from the central metal atom and 10—11 water molecules existed in the region of 5.3 to 6.3 A, probably in the vicinity of peripheral hollows along the C3 axis of the complex. Further, large broad peaks with high electron density were observed around 7.7 and 11.2 A for the [Ru(bpy)3]2+ ion and around 8.0 and 11.5 A for...

X-ray diffraction study on the aggregate structure of 5,10,15,20-tetra(4-sulfophenyl)porphinatopalladium(II)(4-) in aqueous solution

The aggregate structure of 5,10,15,20-tetra(4-sulfophenyl)porphinatopalladium(II) ion (PdTPPS4–) in aqueous solution has been investigated in terms of the distance between the porphyrin monomers, by use of absorption spectroscopy, paramagnetic relaxation of NMR signals, and an isomorphic substitution method for X-ray diffraction of the solution. From absorption spectroscopy results it was concluded that the aggregate was regarded as a dimer arising from hydrophobic attraction between the porphyrin rings. Paramagnetic effects on the longitudinal relaxation time (T1) for 13C NMR of PdTPPS4– by the addition of 5,10,15,20-tetra(4-sulfophenyl)porphinatocopper(II)(CuTPPS4–) suggested that the paramagnetic centre was located along a C4-axis of PdTPPS4– in a PdTPPS4––CuTPPS4– dimer. The dimer of PdTPPS4– was determined to have a twisted face-to-face stacked structure (D4d) at a distance of 4.1 A by the isomorphic substituted X-ray diffraction study on PdTPPS4– and CuTPPS4– solutions.

Conformational Structures of Solvated Co(II) Ions in Amides and Trimethyl Phosphate Studied by X-Ray Diffraction and Isomorphous Substitution

Conformational structures of solvated cobalt(II) ions in several amides and trimethyl phosphate (TMP) have been studied by the X-ray diffraction method using the isomorphous substitution technique. The amides used are formamide (FA), N-methylformamide (NMF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), and N,N-dimethylpropioamide (DMPA). From the analysis of radial distribution functions around Co2+, the distances from Co2+ to each atom of coordinated solvent molecules were obtained and the coordination numbers were determined to be six, except for DMPA where four-coordinate species coexist. The Co—O bond distances are 2.09(1)–2.11(1) Å for six-coordinate species but is 1.96(2) Å for the four-coordinate species. In the amide solutions the Co—O—C bond angles are 126(3)° (FA), 123(2)° (NMF), 123(2)° (DMF), 134(3)° (DMA), and 137(4)–138(4)° (DMPA). The Co—O—C—N dihedral angles were also estimated to discuss the conformational distortion on the Co2+-amide interactions. For TMP solutions the Co—O—P angle was determined to be 150(4)°, and the conformational structure on the Co2+–TMP interaction is discussed.

X-Ray Diffraction Study of the Solvation Structure of the Cobalt(II) Ion in N,N-Dimethylformamide Solution

Abstract The solvation structure of Co2+ in N,N-dimethylformamide (DMF) has been studied by X-ray diffraction measurements on cobalt (II) and magnesium (II) Perchlorate solutions of the same concen tration, using an isostructural substitution method. The radial distribution function revealed three distinct peaks assigned to the oxygen, amido carbon (C1, and nitrogen atoms of six planar DMF molecules in the first coordination sphere around the metal atom. The distance from the cobalt atom to each atom (O, C1, N) is 213,299, and 423 pm, respectively. This indicates that the Co-O-C1 bond angle is 122-123° and the metal atom is close to the O-C1-N plane of the DMF molecule.