Tatsuya Kawamoto

STRUCTURES AND PROPERTIES OF TERNARY COPPER(II) COMPLEXES WITH 4,5-DIHYDROXYPHENYLALANINE OR 2,4,5-TRIHYDROXYPHENYLALANINE AND AROMATIC DIAMINES

Abstract Structural and spectroscopic studies were carried out on ternary Cu(II) complexes, Cu(DA)(AA), with tyrosine derivatives having hydroxyl substituents (AA = 4,5-dihydroxyphenylalanine (dopa) or 2,4,5-trihydroxyphenylalanine (topa)) and aromatic diamines (DA = 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen)). The charge transfer (CT) absorption bands observed as difference absorption spectra in the near-UV region indicate an effective stacking interaction between DA and the side-chain aromatic ring of AA in the ternary Cu(II) complexes. Three complexes, [Cu( dl -topa)(bpy)(H 2 O)] + (complex 1 ), [Cu( l -dopa)(phen)] + [Cu( l -dopa)(CH 3 CH 2 CH 2 OH)(phen)] + (complex 2 ), and [Cu( dl -dopa)(bpy)] + (complex 3 ), were isolated as single crystals, and their structures were determined by X-ray analysis. The central Cu(II) ions in complexes 1 and 3 have square-pyramidal and square-planar geometries respectively. Complex 2 contains two independent molecules having each of the two geometries. All the molecular structures reveal intramolecular aromatic ring stacking between DA and AA in correspondence with the solution spectral observations. The stacking with the topa ring having three hydroxyl groups was found to be slightly stronger than that with the dopa ring having two hydroxyl groups, which is consistent with the more intense CT absorption bands of the topa complex compared with the dopa complex in aqueous solution. Moreover, the oxidative deamination of benzylamine with the ternary Cu(II) complex containing dopa or topa was investigated under aerobic conditions.

Synthesis and characterization of the platinum complexes with N,S or C,N,S ligands derived from 2-phenylbenzothiazoline

Abstract The preparation of the two platinum complexes, the thiolato-bridged tetranuclear [Pt4(phbt)4] and the neutral dithiolene-like-non-innocent mononuclear [Pt(ddbt)], is described. [Pt4(phbt)4] · 2CH2ClCH2Cl crystallizes in the monoclinic space group P21/n, with a = 19.893(5), b = 17.950(7), c = 14.844(4) A, β = 93.69(2)°, V = 5289(3) A3 and Z = 4. [Pt(ddbt)] crystallizes in the monoclinic space group P21/n, with a = 10.789(9), b = 24.56(2), c = 8.64(1) A, β = 102.69(8)°, V = 2232(4) A3 and Z = 4.

Kinetic studies on thiolato-ligand substitution reactions with halide ions of square-planar palladium(II) complex with bis(2-(diphenylphosphino)ethyl)phenylphosphine

Abstract The square-planar thiolato palladium(II) complex with a terdentate phosphine bound ligand, [Pd(pt)(p3)](BF4) (p3=bis(2-(diphenylphosphino)ethyl)phenylphosphine, pt=1-propanethiolate) has been synthesized and characterized by 31P NMR spectroscopy. The solid state structure of [PdI(p3)]I was determined by an X-ray crystal structure analysis. The kinetic parameters for the thiolato-ligand substitution reactions with halide ions, [Pd(pt)(p3)]++X−→[PdX(p3)]++pt− (X−=Cl−, Br−, I−), in chloroform were obtained as follows: k298=7.22, 1.68 and 10.1×10−4 s−1, ΔH‡=67±2, 56±2 and 63±3 kJ mol−1 and ΔS‡=−80±7, −128±6 and −92±11 J mol−1 K−1, respectively. These kinetic results are compared with those for the corresponding reactions of the trigonal-bipyramidal complex with an analogous phosphine bound ligand, [Pd(pt)(pp3)](BF4) (pp3=tris(2-(diphenylphosphino)ethyl)phosphine).

Synthesis and characterization of mononuclear and tetranuclear palladium(II) complexes with 2-(phenylmethyleneamino)benzenethiolate

Abstract Two palladium(II) complexes, [Pd(Hphbt-N,S)2] (1; Hphbt=2-(phenylmethyleneamino)benzenethiolate) and [Pd4(phbt-C,N,S)4] (2), were newly prepared. X-ray and 1H NMR studies indicated the presence of Pd⋯HC interaction in the mononuclear 1, which is assumed to play an important role in the cyclometalation reaction leading to the tetranuclear structure in 2.

Satellite-mill rolling of U-shaped and H-shaped wires

Abstract The satellite mill with closed pass has been successfully applied to production of U- and H-shaped profiled wires. In this study, the influence of rolling parameters such as the pass schedule, the preform dimensions and the surface roughness of the roll groove has been investigated. It is shown that the satellite-mill rolling can form much higher ribs in products than a conventional method and has an advantage in its ability to fill the metal into roll grooves. This effect is enhanced by rougher grooves and by thicker preforms.

The effect of aromatic-aromatic interactions on the crystallization of helical nickel(II) complexes

Abstract Five monometallic helical nickel(II) complexes, with various substituents on the pendant arms, were prepared. The crystal structures of three complexes consist of alternating right- and left-handed helical complexes, with intermolecular face-to-face interactions. On the other hand, the other two complexes crystallize in right-handed or left-handed molecules alone, with intermolecular edge-to-face interactions. This behaviour can be correlated with the electron-releasing properties of the substituents on the pendant arms.

CH/π interaction in nickel(II) complexes derived from 2-substituted benzothiazolines

By reaction of 2-(3,5-di-tert-butyl-4-hydoxyphenyl)benzothiazoline with nickel(II) acetate tetrahydrate, the complex bis[2-(3,5-di-tert-butyl-4-hydroxyphenylmethyleneamino)benzenethiolato]nickel(II) 1 has been prepared. Its crystal structure has been elucidated, showing an intramolecular approach of the tert-butyl group to the aromatic ring of the 2-aminobenzenethiol moiety. In addition, variable-temperature 1H NMR studies of 1 indicated the restriction of rotation of the pendant arm. Such behaviour is attributed to the existence of a CH/π interaction between the tert-butyl group and the aromatic ring of another ligand. To provide further evidence for the CH/π interaction in nickel(II) complexes derived from 2-substituted benzothiazolines, we have also prepared a pair of nickel(II) complexes (2 and 3) with meta-substituted phenyl groups as pendant arms. A comparison between 2 with a methyl group and 3 with a chlorine atom on the pendant arm provided insight into the CH/π interaction that controls the orientation of the pendant arm.

Sulfur-Bridged Co III Pt II Co III Trinuclear Complex Acting as an S-Donating Complex-Ligand

The reaction of fac(S) -[Co(aet) 3 ] (aet=H 2 NCH 2 CH 2 S m ) with [PtCl 2 {Co(aet) 2 (en)}] + gave an S-bridged Co III Pt II Co III trinuclear complex, [Pt{Co(aet) 3 }{Co(aet) 2 (en)}] 3+ ([ 1 ] 3+ ). The crystal structure of [ 1 ]Cl 3 was determined by X-ray crystallography. In [ 1 ] 3+ , the central Pt II atom is coordinated by four thiolato S atoms from octahedral C 2 - cis(S) -[Co(aet) 2 (en)] + and mer(S) -[Co(aet) 3 ] units in a square-planar geometry, giving a linear-type S-bridged trinuclear structure with a non-bridging thiolato group. Treatment of [ 1 ] 3+ with linear Au I produced an S-bridged Co III 4 Pt II 2 Au I heptanuclear complex, [Au{Pt[Co(aet) 3 ][Co(aet) 2 (en)]} 2 ] 7+ ([ 2 ] 7+ ), which indicated that [ 1 ] 3+ acts as a new class of S-donating trinuclear complex-ligand. polynuclear complexes cobalt platinum gold S ligands

2-Bromo-2,3-diphenylmethano-2,3-dihydronaphthoquinone

In the title compound, a diphenylhomonaphthoquinone, C 23 H 15 BrO 2 , the quinone frame adopts a slightly boat-shaped conformation, with folding angles of 11 (3) and 14 (3)°. The severe steric congestion between the endo-phenyl group and the quinone moiety results in considerable freezing of the aromatic ring.

2,3-Benzoquino[15]crown-5

The X-ray structure analysis of the title compound, 2,5,8,11,14-pentaoxabicyclo[13.4.0]]nonadeca-15(1),17-diene-16,19-dione, C 14 H 18 O 7 , reveals that the fused quinone causes a significant deformation of the crown ring from the expected rectangular form, because of the serious steric repulsion between the two carbonyl groups and the two adjacent OCH 2 CH 2 units. One of these units deviates significantly from the mean plane of the quinone, while the other bends inward, remaining coplanar with the quinone. Such a constrained and folded structure is reflected in the abnormal sp 2 bond angles (110 and 130°) of one of the bridgehead quinonoid C atoms.