Yoshihiko Kushi

Important role of CH–π interaction in linkage isomers of bis(2,2′-bipyridine)ruthenium(II) complexes with pyrimidine-2-thione and related ligands

Nine ruthenium(II) complexes containing pyrimidine-2-thione and related ligands were prepared and characterized by elemental analysis, UV/VIS and 1H and 13C NMR spectra: [Ru(L-N,S)(bipy)2]ClO4[HnL = Hpymt (pyrimidine-2-thione), Hmpymt (4-methylpyrimidine-2-thione), Hdmpymt (4,6-dimethylpyrimidine-2-thione), Hapymt (4-aminopyrimidine-2-thione), Hdapymt (4,6-diaminopyrimidine-2-thione), H2tuc(2,3-dihydro-2-thioxo-1H-pyrimidin-4-one, 2-thiouracil), 5-H2mtuc (5-methyl-2-thiouracil), 6-H2mtuc (6-methyl-2-thiouracil) or 6-H2ptuc (6-propyl-2-thiouracil); bipy = 2,2′-bipyridine]. Two linkage isomers, adjacent and remote, exist for all the complexes with unsymmetrical ligands except for apymt. The crystal structure of [Ru(mpymt)(bipy)2]ClO4 was determined. The mpymt ligand co-ordinates through the S2/N3 donors and the complex adopts an adjacent linkage form where the 4-methyl group lies just over one of the bipy chelate rings irrespective of steric hindrance. The CH–π attractive interaction between the 4- or 6-alkyl group of the thione ligand and the π system of bipy affects the isomer ratios in a striking manner.

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.

Preparation and crystal structures of trans-bis(imidato)bis(1,2-diphenylethylamine)copper(II) complexes (imidato=5,5-diphenylhydantoinato and succinimidato). Particular boundary cases of coordination geometry and monodentate ligand conformation.

Abstract Two new copper(II) complexes, trans- [Cu(phent) 2 ( R -diphenea)( S -diphenea)]·2CHCl 3 ( 1 ) and trans- [Cu(succim) 2 ( R -diphenea)( S -diphenea)] ( 2 ) (phent=5,5-diphenylhydantoinate, succim=succinimidate, and diphenea=1,2-diphenylethylamine) were prepared and crystal structures were determined. Nevertheless both complexes have the same diphenea ligands, 1 affords a distorted square planar [CuN 4 ] coordination with imidate and amine trans -NCuN bond angles 156.6(2) and 161.4(2)°, while 2 affords a square planar [CuN 4 ] coordination with both trans -NCuN bond angle 180.0°. Complex 2 was the first example of square planar [CuN 4 ] complexes with 1-phenyl substituted ethylamine derivatives. Structural features are compared among 1 , 2 , and previously reported distorted square planar trans- [Cu(phent) 2 ( R -phenea)( S -phenea)] ( 3 ) and trans- [Cu(succim) 2 ( R -phenea)( S -phenea)] ( 4 ) (phenea=1-phenylethylamine) complexes. The structural features suggest that the [CuN 4 ] coordination environment of 1 is distorted by particular edge-to-face arrangement of phenyl groups of amines and imidates which reasonably corresponds to the most and the second stable conformation of diphenea ligands with respect to rotation of two phenyl groups.

Structures of Fe(III) complexes with EDTA and EDDDA in aqueous solution by EXAFS and XANES

Abstract The Fe K-edge X-ray absorption spectra of Fe(III) complexes with EDTA (ethylenediaminetetraacetic acid) and EDDDA (ethylenediamine- N , N -diacetic- N , N ′-dipropionic acid) in weakly acidic or neutral aqueous solutions are measured. The spectra of powdered crystalline samples of these complexes are also measured as the reference materials. The comparisons of the XANES spectra, including their pre-edge peak, and the EXAFS Fourier transforms conclude that in aqueous solution a seven-coordinate structure is predominant for the Fe(III)-EDTA complex and a six-coordinate one for the Fe(III)-EDDDA complex.

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.

Rotamers of the 1-phenylethylamine ligand in trans- bis(imidato)bis(1-phenylethylamine)copper(II) complexes, where imidato = 3,3-dimethylglutarimidato, hydantoinato and succinimidato ligands

Abstract Three [CuN4] complexes, red trans-[Cu(3,3-dmgluim)2(R-phenea)2] (1), blue-violet trans-[Cu(hyd)2(R-phenea)2] (2) and blue trans-[Cu(succim)2(S-phenea) (R-phenea)] (3) (3,3-dmgluim=3,3-dimethylglutarimidato, hyd=hydantoinato, succim = succinimidato, phenea = 1-phenylethylamine), were prepared and their crystal structures were determined. Crystal data are as follows: 1 is monoclinic, space group P21, a = 14.854(1), b = 17.105(3), c-5.988(2) A, β=91.65(1)°, U=1520.8(5) A3, Z=2, R=0.033, and 2318 reflections; 2 is monoclinic, space group P21, a = 19.946(2), b = 6.035(1), c = 10.025(1) A,β= 104.383(7)°, U= 1168.9(3) A3, Z=2, R =0.035, and 1864 reflections; 3 is triclinic, space group P 1 , a = 12.434(4), b = 12.670(3), c = 8.765(2) A, α=94.83(2), β= 112.87(2) γ=73.15(2)°, U= 1219.9(6) A3, Z=2, R=0.054, and 3678 reflections. In 1 the coordination geometry is planar, and the specific intermolecular hydrogen bonds are formed along the c axis between H(NH2) of phenea and O(CO) of the six- membered cyclic imidate. In 2 and 3 the coordination geometries are tetrahedrally distorted. The intramolecular hydrogen bonds are formed between H(NH2) of phenea and O(CO) of the five-membered cyclic imidate. Three different staggered forms of and one eclipsed form of rotamers in the phenea ligands have been found.

The structure and absolute configuration of (–)-2β,9α-dihydroxyverrucosane isolated from the liverwort Mylia verrucosa : X-ray analysis of the mono-p-bromobenzoate

The structure of dihydroxyverrucosane (I), a novel diterpene-diol isolated from the liverwort Mylia verrucosa has been determined from single-crystal X-ray analysis of the mono-p-bromobenzoate (II) by the heavy-atom method. The crystals were monoclinic, a= 6.670(1), b= 19.269(1), c= 10.379(1)A, β= 112.6(4)°, space group P21, Z= 2. Block-diagonal least-squares refinement based on 1 929 independent reflections converged to R 0.078. The absolute configuration was established by the anomalous dispersion effect. The molecule contains a 3,6,6,5-tetracyclic ring system in which ring B is considerably distorted by fusion with the cyclopropane ring A. Ring C adopts a chair conformation and ring D is a conformation somewhere between a half-chair and β-envelope.

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.

Formation of a nickel(II) complex with a new N2S2 macrocyclic ligand by C–Cl bond cleavage and C–S bond formation

Heating a monohelical square-planar nickel(II) complex containing chlorine atoms in the side arms gives a distorted octahedral nickel(II) complex containing the trans-N2S2 macrocyclic ligand by carbon–chlorine bond cleavage and carbon–sulfur bond formation.

Rhenium complexes containing an η2-thiocarbamoyl group: synthesis, electrochemistry, and crystal structure of [Re(S2CNEt2)2(SCNEt2)(PPh3)]ClO4

A new redox couple of rhenium complexes, [ReIII(S2CNEt2)2(SCNEt2)(PPh3)] and [ReIV(S2CNEt2)2(SCNEt2)(PPh3)]ClO4, has been isolated and electrochemically characterized; the η2-co-ordination of the N,N-diethylthiocarbamoyl group in the latter has been confirmed by X-ray analysis.