Setsuko Kinoshita

The behavior of organic counterions in the micelle of alkylammonium decylsulfonates

Abstract The behavior of organic counterions in the micellar state was studied for alkylammonium decylsulfonate systems by 13 C NMR and conductivity measurements. The chemical shifts of C 2 ′C 5 ′ carbon atoms in n -butylammonium and n -pentylammonium ions showed a downfield shift of 0.2–0.6 ppm in comparison with those of the corresponding chlorides. Moreover, the spin—lattice relaxation time T 1 of the decylsulfonate ions had irregularities caused by collision between the decyl chains and the terminal methyl group of the counterions when the counterions were n -butylammonium and n -pentylammonium ions. The conductivity measurements indicated that the degree of dissociation of the counterions decreases with increasing counterion chain length. These facts can be explained by the long-chain counterions forming a mixed micelle with decylsulfonate ions while the short ones do not.

NMR investigation of bis(2,3-alkanedione dioximato)-bis(pyridine)cobalt(III) iodide complexes: 1H and 13C NMR spectra and 13C spin-lattice relaxation time measurements

Abstract The complexes of trans-[Co(III)(R,CH3-dioxH)2(py)2]I† (R = CH3, C2H5, n-C3H7 and n-C4H9) were investigated in solution by 1H and 13C NMR spectra and 13C spin-lattice relaxation time measurements. The 1H and 13C-resonances of the R = C2H5, n-C3H7 and n-C4H9) groups were shifted to higher field than those of the free ligands by the complexation; it was attributable to the ring current shielding due to the axial pyridine ligands of the complexes. 13C spin-lattice relaxation times were interpreted as due to movement of the axial pyridine ligands as if they twist around the CoN (pyridine nitrogen) bond axis and the above R groups were moving segmentally. These segmental movements allowed the R groups to approach closely toward the axial pyridine ring plane to experience the ring current shielding.

A spectrophotometric method for the determination of nitric oxide

In dimethylsulfoxide, nitric oxide reduces copper(II) to copper(I) in the presence of p-chloroaniline. The resulting copper(I) is determined spectrophotometrically with 2,2′-biquinoline. The reactions are reproducible and the absorbance is proportional to the concentration of nitric oxide over the range 1.8–108 ppm (mg dm−3. Most other atmospheric contaminants are without effect.

Kinetics of thermal decomposition of substituted pyridine adducts of N,N'-ethylenebis(salicylideneaminato)cobalt(II) in the solid state

Abstract Kinetic and thermodynamic aspects of the axial base dissociation of solid Co(salen) (X-py) complexes, X = H ( 1 ), 3-Me ( 2 ), 4-Me ( 3 ), 3,4-Me 2 ( 4 ), 3,5-Me 2 ( 5 ), 3-NH 2 ( 6 ), 3-Cl ( 7 ), 3-CN ( 8 ), 4-CN ( 9 ), have been investigated by means of TG-DSC and isothermal weight-loss measurements. These adducts endothermically dissociate the axial base giving rise to the oxygen-active Co(salen) complex. The axial base dissociation reactions fit the contracting disc equation and the kinetic compensation effect is observed for all the adducts excepting Adducts 4–6 . For the remaining adducts the kinetic and thermodynamic stabilities of the Co-(X-py) bond are found to increase linearly with increasing Hammetts substitution constants of X except for Adducts 3 and 9 . These results are discussed in terms of the σ and π interactions between cobalt(II) and substituted pyridine. Factors dominating the kinetic bond stability are briefly discussed.

Nmr investigation of nickel(II) scriff base complexes with benzoyl substituents

Abstract The nickel(II) Schiff base complexes with isobutyl chains and benzoyl substituents have been prepared and characterized by 1H and 13C NMR spectroscopies. In the complex, the donor set of N2O2 has a square planar coordination, the benzoyl substituents are perpendicular to the chelate plane and the isobutyl groups move segmentally so that they may approach the benzoyl substituents.

Thermal intramolecular electron transfer reactions of [N,N′-ethylene-bis(salicylideneaminato)](2,4-pentanedionato)cobalt(III) complexes in the solid state

Abstract The title complexes with the formula Co(salen)L where L is a series of 2,4-pentanedionates underwent thermally induced one-electron transfer reactions from L to Co(III). The reaction left behind a stoichiometric amount of the crystalline Co II (salen) complex which took up oxygen in a molar ratio of Co:O 2 = 2:1. The kinetic analyses showed that the electron transfer reaction rate was apparently dominated by activation entropy rather than by activation enthalpy.

Solid-state high-resolution carbon-13 magnetic resonance spectra of dithioacetate complexes of platinum, palladium, and nickel

High-resolution 13C n.m.r. spectra were measured for platinum, palladium, and nickel dithioacetato complexes with various structures and oxidation states in the solid state. The [Pt2(S2CMe)4] complex showed one methyl signal, while [Ni2(S2CMe)4] and [Pd2(S2CMe)4] showed two and three methyl signals, respectively. These results are well explained in terms of the single-crystal X-ray structures of these complexes. Compared with the spectrum of [Pt2(S2CMe)4], the quaternary carbon signal of [Pt2(S2CMe)4I2] is shifted to lower-field, while the methyl signal appears at a similar position, indicating the greater effectiveness of Pt3+ over Pt2+ in removing electron density from the surrounding quaternary carbon atoms. The one-dimensional [M2(S2CMe)4I](M = Ni or Pt) complexes showed two broad methyl signals owing to the slight magnetism.