Mitsuharu Fujita

Optically active sulfur-bridged Co(III)–M(II) (M=Pd, Pt) dinuclear complexes with square-planar [M(μ-S)2(bpy)] (bpy=2,2′-bipyridine) frameworks derived from octahedral bidentate sulfur-donating Co(III) metalloligands

Abstract The reactions of the optically active octahedral mononuclear complex, trans(N)-[Co( d -pen)2]− ( d -pen= d -penicillaminate), with [PdCl2(bpy)] (bpy=2,2′-bipyridine) and [PtCl2(bpy)] stereoselectively gave the S-bridged dinuclear complexes, [Pd(bpy){Co( d -pen)2}]+ (1a) and [Pt(bpy){Co( d -pen)2}]+ (1b), respectively. A similar optically active S-bridged dinuclear complex, Δ-[Pt(bpy){Co(aet)2(R-pn)}]3+ (2b; aet=2-aminoethanethiolate, pn=1,2-propanediamine), was also obtained by the substitution reaction of ΔΔ-[Ni{Co(aet)2(R-pn)}2]4+ with [PtCl2(bpy)]. The crystal structures of 1a, 1b, and 2b were determined by X-ray crystallography, and compared with that of the previously reported Δ-[Pd(bpy){Co(aet)2(R-pn)}]3+ (2a). The Co(III) equatorial planes and the PdN2S2 or PtN2S2 square planes in the 1a and 1b are almost coplanar, while those in 2a and 2b are somewhat bent from each other. In addition, the distortions from the square planes to tetrahedrons in 2a and 2b are more pronounced than those in 1a and 1b. Furthermore, all of the bridging S atoms in 1a and 1b are stereoselectively unified to the S configuration, in contrast to those in 2a and 2b with the R configuration. These reflect the differences of the optically active Co(III) units in these complexes. The electronic absorption, CD, and 13C NMR spectral behaviors of these complexes are also discussed in relation to their crystal structures.

Localized π electronic edge state in nanographite

Graphite fragments on a nanometer scale can present a distinctive edge state depending on the edge shape. By examining the electronic band structure of graphite ribbons within the Pariser-Parr-Popl...

Electronic Structure and Surface-Localized State of Hyper-Graphite Network

Abstract We study electronic structures of an extended three-dimensional graphite network and its slab performing of the tight binding model. The one of networks we study is bipartite and three-coordinated, and also found in some materials like α-ThSi 2 . The electronic structures of this networks have characters which are peculiar to 2D graphite. One of these characters is that these networks are a semi metal and the other is that these networks which are cut in proper direction have a surface localized states (Edge State), which originate from the topological feature of the network as well as the zigzag edge in 2D graphite. We call these networks which are made by concept extending graphite network for higher dimensions ‘the Hyper Graphite’.

Electron-Phonon and Electron-Electron Interactions in Nanographite Ribbons

Abstract Graphite fragments of nanometer size, called nanographite, have a different electronic structure than both bulk graphite and aromatic molecules. In particular, if they have zigzag edges, a sharp peak in the density of states at the Fermi level is generated, suggesting to cause Fermi instability. We have studied the lattice distortion and the possible magnetization based on the model of graphite ribbons with a nanometer width, by taking into account the electron-phonon and electron-electron interactions in the form of a tight binding model.

Linear-Type S-Bridged Trinuclear Complexes with RuIII Ion and Octahedral fac(S)-[M(aet)3] Units (M = RhIII, IrIII; aet = 2-Aminoethethiolate)

ABSTRACT The reactions of fac(S)-[M(aet)3] (M = RhIII, IrIII; aet = 2-aminoethanethiolate) with RuCl3 · 3H2 O in water gave trinuclear complexes, ΔΛ-, ΔΔ/ΛΛ-[Ru{Rh(aet)3}2]3+ ( 1a, 1b ) and ΔΛ-, ΔΔ/ΛΛ-[Ru{Ir(aet)3}2]3+ ( 2a, 2b ). The crystal structure of 2a (NO3)3 · 3H2 O revealed that the central RuIII ion is coordinated by six S atoms from two fac(S)-[Ir(aet)3] units in an octahedral geometry, forming a linear-type S-bridged trinuclear structure. It was found that the UV-Visible (UV-Vis) spectral patterns of all complexes depend upon the terminal fac(S)-[M(aet)3] units. In the electro- and spectroelectrochemistry of these complexes, the Ir trinuclear complex showed a reversible [Ru{Ir(aet)3}2]3+/4+ redox process.

Electronic states and phason lines on higher fullerenes

Summary form only given. For the geometrical understanding of general fullerenes, we propose the use of a projection method based on a honeycomb lattice. The formation of general fullerenes like C)/sub 60/, C)/sub 70/, C)/sub 76/, C)/sub 78/ ... is completely specified by the distribution of twelve pentagonal defects on a honeycomb lattice. Based on this method, we study the texture of the bond alternations on higher fullerenes, utilizing on the extended Su-Shrieffer-Heeger model to the honeycomb network where the the electron-phonon interaction are taken into account. We demonstrate that the lattice distortion and the charge distribution caused by the bond alternations are well understandable by introducing a concept of phason line on the geometries of higher fullerenes. The phason line is defined as the boundary between the domains where the Kekule patterns of bond alternations with different phase stand. Therefore the bond alternations give rise to be frustrated along the phason line and the lattice distortions axe enfeebled. The stability, reactivity, effect of electrons and holes doping and photo-excited states of higher fullerenes are discussed.

Bis(μ‐cyst­amine‐κ4N,S:S′,N′)­bis­[(2‐amino­ethane­thiol­ato‐κ2N,S)­iridium(III)] tetrabromide dihydrate

In the complex cation of the title compound, [Ir2(C2H6NS)2(C4H12N2S2)2]Br4.2H2O, which was obtained by rearrangement of [Re[Ir(aet)3]2]3+ (aet is 2-aminoethanethiolate) in an aqueous solution, two approximately octahedral fac(S)-[Ir(NH2CH2CH2S)3] units are linked by two coordinated disulfide bonds. The complex cation has a twofold axis, and the two non-bridging thiolate S atoms in the complex are located on opposite sides of the two disulfide bonds. Considering the absolute configurations of the two octahedral units (Delta and Lambda) and the four asymmetric disulfide S atoms (R and S), the complex consists of the Delta(RR)Delta(RR) and Lambda(SS)Lambda(SS) isomers, which combine to form the racemic compound.