Bis(µ(2)-4,7-dimethyl-4,7-diazadecane-1,10-dithiolato)trinickel(II) bis(perchlorate).

In the title compound, [Ni(3)(C(10)H(22)N(2)S(2))(2)](ClO(4))(2), the complex cation consists of a nickel(II) ion and two [Ni(C(10)H(22)N(2)S(2))] units with an N(2)S(2) tetra-dentate ligand, 3,3'-[1,2-ethane-diylbis(methyl-imino)]bis-(1-propane-thiol-ate). The central Ni(II) ion is located on a crystallographic inversion centre and is bound to the four S atoms of the two [Ni(C(10)H(22)N(2)S(2))] units to form a linear sulfur-bridged trimetallic moiety. The dihedral angle between the central NiS(4) plane and the terminal NiN(2)S(2) plane is 145.71 (5)°. In the [Ni(C(10)H(22)N(2)S(2))] unit, the two methyl groups on the chelating N atoms are cis to each other, and the two six-membered N,S-chelate rings adopt a chair conformation. The Ni-S bond lengths and the S-Ni-S bite angles in the central NiS(4) group are similar to those in the [Ni(C(10)H(22)N(2)S(2))] unit.

Steric, geometrical and solvent effects on redox potentials in salen-type copper(II) complexes.

Two diastereomers of the Schiff base ligand [N,N'-bis(2'-hydroxyphenyl)phenylmethylidene]-1,2-diamino-1,2-diphenylethane (H(2)L) were used for the analyses of the redox behaviour of the copper(ii) complexes [Cu(L(R,R/S,S))] (rac-) and [Cu(L(R,S))] (meso-). Both complexes were structurally characterised by X-ray crystallographic studies and showed square planar geometries. The reduction potential of Cu(II) to Cu(I) for meso- was higher than that for rac-. This is due to the steric effect of the phenyl substituents and the geometrical change in the copper(i) state, which is supported by DFT calculations. A red shift of the absorption spectrum was observed for meso- in the visible region by the change of solvent from dichloromethane to pyridine, while rac- did not show a significant change. The effect of solvent on the reduction potential was found to be relatively small. The geometrical effect is more important for understanding the electrochemical behaviour in this system.

(1)H-NMR study of ternary platinum(II) complexes with N-(1-Naphtyl)methyl-1,2-ethanediamine or N-(9-anthrylmethyl)-1,2-ethanediamine and bipyridine or phenanthroline and restricted single bond rotation due to aromatic-aromatic ring interaction.

(1)H-NMR spectra of square-planar complexes with the formula [Pt(L(1))(L(2))]X(2) where L(1) is 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and L(2) is N-(1-naphthyl)methyl-1,2-ethanediamine (Npen) or N-(9-anthryl)methyl-1,2-ethanediamine (Aten) indicate that the N-naphthylmethyl and N-anthrylmethyl groups are forced to adopt a pseudo axial disposition due to intramolecular repulsion of hydrogen atoms of the aromatic diimines. The aromatic-aromatic interactions in the N-arylmethyl-1,2-ethanediamine complexes and aromatic diimines caused them to undergo intramolecular stacking. (1)H-NMR spectra of these complexes showed a significant concentration and temperature dependence. The monomer-dimer equilibrium was estimated, based on the concentration dependency. Restricted single bond rotation was estimated from temperature dependency data. The rotation of the anthracene ring of the [Pt(bpy)(Aten)](2+) complex showed an activation energy of ca. 38 kJ mol(-1), which is in good agreement with a mechanism involving successive rotations about single bonds with restriction by intramolecular aromatic-aromatic ring interactions.

An unexpected chelate conformation in trans-[(R)-N,N'-bis(alpha-phenylsalicylidene)propane-1,2-diaminato(2-)]bis(1-methyl-1H-imidazole-kappaN3)cobalt(III) perchlorate.

The title compound, [Co(C29H24N2O2)(C4H6N2)2]ClO4, contains an optically active tetradentate Schiff base ligand in an equatorial plane and two 1-methylimidazole ligands at apical positions. The central N-C-C-N chelate ring of the Schiff base ligand has an envelope structure with a lambda conformation, which is different from the solution structure predicted from circular dichroism and 1H NMR spectra.

Microwave-assisted simple ion-exchange of ZSM-5-type zeolites with copper ions and their specific adsorption properties for N2 molecules at room temperature.

Copper ion-exchanged ZSM-5 samples, prepared using an easy method that takes advantage of microwaves, exhibit a quite peculiar adsorption feature for dinitrogen molecules, in that a large volume of chemisorbed N2 was detected, even at room temperature, and the specificity of the adsorption properties was clarified by comparing with the properties of samples prepared by an ordinary ion-exchange method.

Syntheses, Characterization, and Molecular Mechanics Calculations of Optically Active Silatrane Derivatives.

A series of optically active silatrane derivatives, [Si{N(CHRCH(2)O)(CH(2)CH(2)O)(2)}X] (R = Me, i-Pr; X = Ph, OMe) has been synthesized by the reaction of optically active triethanolamine derivatives with XSi(OMe)(3), and characterized by (1)H NMR, (13)C NMR, (29)Si NMR, and mass spectroscopy, and the structures of six compounds have been determined by X-ray analysis. Molecular mechanics methods have also been employed to obtain the energy-minimized structures. The (29)Si NMR chemical shifts and the lengths of Si-N determined by X-ray analysis are sensitive to the bulkiness of the substituent (R). The Si-X bond lengths (X: trans position to nitrogen) do not appreciably differ from one another. The MM2 calculations indicated that the substituent exists in the equatorial position, and the results are in agreement with those of X-ray analysis and (1)H NMR spectroscopy. Crystallographic data: [R = H; X = OMe], C(7)H(15)NO(4)Si, orthorhombic, Pna2(1), a = 13.407(1) Å, b = 8.761(2) Å, c = 8.191(1) Å, Z = 4; [R = Me; X = OMe], C(8)H(17)NO(4)Si, orthorhombic, P2(1)2(1)2(1), a = 10.110(3) Å, b = 11.083(2) Å, c = 9.474(2) Å, Z = 4; [R = i-Pr; X = OMe], C(10)H(21)NO(4)Si, monoclinic, P2(1), a = 8.481(1) Å, b = 7.805(1) Å, c = 10.218(2) Å, beta = 111.31(1) degrees, Z = 2; [R = Me; X = Ph], C(13)H(19)NO(3)Si, orthorhombic, P2(1)2(1)2(1), a = 8.813(1) Å, b = 11.137(2) Å, c = 13.757(1) Å, Z = 4; [R = i-Pr; X = Ph], C(15)H(23)NO(3)Si, orthorhombic, P2(1)2(1)2(1), a = 8.365(1) Å, b = 13.538(2) Å, c = 13.841(2) Å, Z = 4.