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The Raman spectra of alpha form 5-nitro-2,4-dihydro-1,2,4-triazole-3-one (alpha-NTO, space group P) were measured in a high-pressure vessel diamond anvil cell (DAC). The pressure was increased to 27.6 GPa. In general, Raman bands show a blue shift because of the nature of the molecule packing as a high-pressure effect, but some particular bands exhibited a red shift, disappearance, split, or slight shifting in our experiments. Those red-shifting bands concerning hydrogen bonds, i.e., carbonyl and amino groups, are likely to work as a stabilizer against stimuli to the molecule or crystal. This stabilizing nature might characterize the insensitivity of NTO. Molecular dynamic (MD) calculations were performed to reveal the high-pressure effect of the alpha-NTO crystal. The coordinates of individual atoms in the crystal structure were obtained using X-ray diffraction analysis. The pressure dependence of the power spectra of the correlation functions of the C=O bond length in NTO was calculated. A unique high-pressure effect of the alpha-NTO crystal was found on the power spectra. The peak frequency in the power spectrum of the C=O stretching vibration exhibited a red shift with an increase in pressure to 10.0 GPa, while the peak intensity considerably decreased under the same pressure process, because this bond length increased with an increase in pressure to 10.0 GPa. At a pressure of >20.0 GPa, a blue shift appeared. These results of the MD calculations are in good agreement with our experimental data.

In the title compounds, [Co(C 2 O 4 )(CH 5 N)) 4 ]ClO 4 (1), and [Co(C 2 O 4 )(C 2 H 7 N) 4 ]ClO 4 .H 2 O, (2), the Co atom has a distorted octahedral coordination composed of four amine ligands and one oxalato ligand. The coordination and oxalato bond distances in (1) and (2) are similar to the corresponding distances in [Co(C 2 O 4 )(NH 3 ) 4 ] + . The Co-N-C angles are in the range 117.1 (4)-123.2 (2)°.

The title compounds, [N,N'-bis (2-pyridylcarbonyl)-propane-1,3-diaminato-κ 4 N]paliadium(II) monohydrate, [Pd(C 15 H 14 N 4 O 2 )].H 2 O, and [N,N'-bis(2-pyridylcarbonyl)propane-1,3-diaminato-κ 4 N]nickel(II) monohydrate. [Ni(C 15 H 14 N 4 O 2 )].H 2 O, were investigated by means of X-ray diffraction and high-resolution NMR. The Pd II and Ni II ions have regular and distorted square-planar coordination geometries, respectively. Libration of the propanediyl chains in these complexes was observed in both the crystalline and solution states.

The self-assembly between hexakis(4-carboxyphenoxy)cyclotriphosphazene (1) and hexakis(4-pyridylcarbinoxy)cyclotriphosphazene (2) was investigated. FT-IR spectra and elemental analysis of crystals (3) obtained from a solution containing 1 and 2 in equimolar ratio in DMF suggested that all the carboxyl groups in 1 interact with pyridyl groups in 2 to form a 1:1 complex. The X-ray analysis of 3 showed that the crystals, defined by R=0.054 based on 4212 data, I>3.0 σ(I) , are monoclinic, space group P21/n with a=13.636(6), b=24.71(1), c=23.56(1) A, β=102.36(3)°, V=7754(6) A3, and Z=4. The hydrogen bonded NHO distance ranges from 2.61 to 2.82 A with an average distance 2.69 A and the phenoxy group in the crystals stacked with pyridyl group in the neighboring molecules, leading to the construction of 1:1 1–2 cylindrical structure 3. The characterizations of self-assembly 3 based on cyclophosphazene derivatives are described.

Sedimentary calcium carbonate was grown at a physiological pH6.8 from a mixture of equivolume of 70 mM Ca(NO 3 ) 2 and 70 mM NaHCO 3 aqueous solution. The kinetics of the crystal growth was monitored by means of turbidity measurement. The apparent absorption is gradually increased with the elapsed time after the mixing and reaches its maximum at t max . The average t max is significantly decreased from 〈 t max 〉=467 s (for n =13 runs) to 408 s ( n =13) by application of the static magnetic field (SMF) of H =400 mT to the precipitating solution. The application of SMF at 120 s later the mixing shows the same 〈 t max 〉=396 s ( n =9) as that of 408 s. It has been thus detected that the application of SMF is ineffective in the stage of the nucleation or the earlier stage of the crystal growth but effective in the Ostwald ripening stage of the growth nucleus or the later stage of the crystal growth where large numbers of the growing crystalline particles seem greater than a few hundred nanometers. A possible mechanism for the SMF effect is as follows. An ion escaping from the growing crystal surface with a certain ‘migration velocity' due to a random walk process has significant probability to drift onto the identical surface or at least the identical crystal by means of Lorentz force, because the translational displacement of the crystal during a cycle of the cyclotron motion of the ion is smaller than the size of the growing crystal. This type of drift results in the suppression of re-dissolution of the ions on the growing surface and in the acceleration of the growth in the later stage of the crystal growth. The undetected SMF effect in the earlier stage of the crystal growth can be partly attributed to the re-dissolution due to the thermodynamic instability of the small nuclei which predominates over the presumable SMF effect. This can be partly ascribed to the large translational displacement of the small particle. The application of this mechanism to an oscillating magnetic field will predict the presence of a window for the frequency of the oscillating magnetic field.

An idea for a relation between the frequency and intensity of the optimal oscillating magnetic field for the magnetic effects has been presented. An estimated optimal frequency is about 150 Hz for a system containing ions of effective molecular weight of M ≈100 under a square pulsing magnetic field of intensity H =1 mT.

The crystal structure of 1,3,5-triphenyl-6-methylverdazyl has been determined by X-ray diffraction. The crystals are orthorhombic, with the space group of Pnma and with a=18.25(1), b=16.65(1), c=5.776(2) A, and Z=4. The structure was deduced from the sharpened Patterson synthesis and was refined by the block-diagonal least-squares method to the final R value of 0.055 for 960 non-zero reflections collected on an automated four-circle diffractometer. The sym-tetrazinyl ring has an asymmetrical boat form, as has been observed in both 1,3,5-triphenylverdazyl and 1,3,5-tri-p-tolylverdazyl. The complete intermolecular overlap was observed in a tilted face-to-face array along the c-axis; this accounts for a fairly strong antiferromagnetic exchange interaction between the unpaired electrons.

Single-crystal ESR studies have been carried out on symmetrical triphenylverdazyl (TPV) doped in a diamagnetic 1,3,5-triphenylbenzene (TPB) crystal at room temperature. There have appeared seven pairs of fine-structure absorptions in addition to the hyperfine splittings. Three out of the seven pairs have been assigned as zero-field splittings due to radical pairs, while the other three pairs have been identified as from radical triads. The six fine structure tensors have been determined through the angular variation of the resonance-field separations. The structures of the pairs and triads of TPV were discussed on the basis of the fine structure tensors, the crystal structures of TPB and TPV, and the spin distribution in the radical molecule, assuming that the unit cell of the mixed crystal with the radical concentration of less than 11.1% is identical with that of the host crystal, TPB. Within the limits of the X-ray examination, this assumption was found to be reliable. It was found that the molecular p...

The crystal structure of 1,3,5-tri-p-tolylverdazyl has been determined by X-ray diffraction. The crystals are monoclinic, with the space group of P21/m and with a=8.173(3), b=20.23(1), c=6.075(2) A, β=105.4(1)°, and Z=2. The structure was deduced from the sharpened Patterson synthesis and refined by the block-diagonal least-squares method to the final R value of 0.048 for the 1212 non-zero reflections collected by the counter-method. The sym-tetrazinyl ring has an asymmetrical boat form. The molecules are arranged approximately parallel to the (20\bar1) plane. The maximum intermolecular overlap is observed between the sym-tetrazinyl and C-tolyl groups, suggesting a weak exchange interaction between unpaired electrons.

A binuclear complex of bis(μ-N,N′-dipicolinoyl-1,3-propanediamine)-bis(sulfato)dicopper(II) has been isolated as a blue single crystal tridecahydrate, [{Cu(SO4)(ppda)}2]·13H2O, from an aqueous solution. The crystals are orthorhombic, C2221, with a=15.42(1), b=24.92(2), c=25.73(2) A, and Z=8. Each copper(II) ion is in a square-pyramidal coordination with two pyridine nitrogen atoms, two carbonyl oxygen atoms, and a sulfate oxygen atom at the apex. The two equivalent copper(II) ions, about 3.9 A apart from each other, are aligned coaxially. The eight Cu–Cu vectors are approximately parallel to one another along the c axis. The most important feature of the crystal structure is the presence of the bulky ligands and of many water molecules, which magnetically isolate the Cu–Cu coupled pair from one another. This facilitates the ESR study of the molecular anisotropies by using the single crystal, even at room temperature. The ESR parameters determined are as follows: g⁄⁄=2.280(2), g⊥=2.067(1), |D|=422.4(8), |A...

The magnetic susceptibility of 1,5-diphenyl-3-(4-chlorophenyl)verdazyl (Cl-TPV) has been measured on a powder sample in the temperature region between 1.8 and 80 K. It exhibited a round maximum at 21.0 K; this temperature is the highest among those observed for verdazyl monoradicals. The susceptibility can be well described by the Heisenberg linear chain model; the estimated exchange interaction parameter is J⁄k=−16.4 K. The crystal structure of Cl-TPV has been determined by means of X-ray diffraction. The crystal is orthorhombic, with the space group of Pbca and with a=22.041(5), b=7.166(4), c=21.379(5) A, and Z=8. The molecules are arranged in a column along the b axis. The exchange interaction has been discussed based on the crystal structure and the spin density distribution.

Angular-dependent ESR measurements were carried out at 77 K for 65Cu(II) ions doped in a single crystal of benzo-15-crown-5 (B15C5) magnesium complex. Not only the allowed resonance lines of copper(II) ions, but also the forbidden lines arising from a nuclear quadrupole interaction were observed. Based on an analysis of the single crystal ESR spectra, the spin Hamiltonian containing the quadrupole term was determined for a B15C5–65Cu(II) complex having a 3dz2 ground state in a B15C5–Mg(II) solid matrix.

The exchange interactions in four kinds of verdazyl crystals, 2,4,6-triphenylverdazyl (TPV), 2,4,6-triphenyl-3-methylverdazyl (MeTPV), 2,4,6-tri-p-tolylverdazyl (TTV), and 2,6-di-p-tolyl-4-phenylverdazyl (DTPV), have been studied by means of McConnell’s spin density Hamiltonian. The calculated exchange parameters, J, have been compared with the experimental values derived from the magnetic susceptibilities. The observed order of J’s J⁄k=−5.4 (TPV), −9.1 (MeTPV), −11.1 (DTPV), and 0–−0.3 K (TTV), can be qualitatively explained by the following equation:J∝\undersetijΣ (−1⁄rij)ρilρjl+1,where ρil and ρjl+1 are π-spin densities on atoms i and j of the l-th and (l+1)-th molecules in the crystallographic column and rij is the interatomic distance between atoms i and j. The magnetic susceptibility data of MeTPV and TTV between 1.6 and 300 K are presented and interpreted with the Heisenberg linear chain model. The susceptibility of DTPV is re-interpreted in the same framework as above.

X-band and Q-band ESR measurements of Mn(II) ions contained in Japanese cultured marine pearls and pearl oyster (Pinctada fucata) were carried out at room temperature. The ESR spectra observed for the powdered samples of nacreous and prismatic layers revealed the ESR hyperfine structures typical to Mn(II) in an aragonite lattice and a calcite lattice, respectively. The ESR spectra were interpreted with the following spin Hamiltonian.\mathscrH=gβH·S+aS·I–gnβnH·I+D[Sz2–S(S+1)⁄3]+E(Sx2–Sy2)The resonance fields for all the M=+1⁄2↔M=−1⁄2 ESR transitions were derived, with the third-order corrections all taken into account. The zero-field splitting parameters D and E for Mn(II) ions in these biominerals were estimated by computer simulations of the ESR line shapes. The estimated parameters for the nacreous Mn(II) ion (D=20.8 mT, E=6.9 mT) are apparently different from those for the prismatic Mn(II) ion (D=8.5 mT, E=1.4 mT).

In the presence of the optimum amount of water, the copper(II) ion and 15-crown-5 (15C5) derivatives gave the dihydrated complex in boron trifluoride–diethyl ether (BF3–ether). Based on optical and ESR spectrometric titrations, we found that the crown ether captures the copper(II) ion in the equivalent metal/ligand molar ratio. The d–d band absorptions of the complexes were detected in the near-infrared region. The complexes revealed the characteristic ESR g-anisotropies (gz

The static magnetic susceptibility and the ESR spectra from 1.6 to 300 K have been measured on a powder sample of the titled free radical. The broad maximum in the susceptibility which indicates an antiferromagnetic interaction has been observed at 6.9 K. The broadening of the ESR absorption line and the shift of the g-value have been found in the temperature region below Tmax, in which the susceptibility reached its round maximum. There appeared anomalies in the slope of the susceptibility, the linewidth, and the g-value versus temperature curves in the vicinity of 1.7 K. These anomalies may imply a magnetic-phase transition from the short-range ordered state to the long-range ordered state at about 1.7 K. The existence of a ferromagnetic interaction between the magnetic chains in the triphenylverdazyl radical solid is discussed on the basis of the susceptibility, the spin distribution, and the crystal structure. It is understood qualitatively that the radical with a negative spin density has a latent fe...

The ENDOR spectra of 1,3,5-triphenylverdazyl radical and its methyl derivatives were observed in toluene, and the effects of methyl substitution on the proton hyperfine coupling constants were investigated.