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Measurement of the quenching rate constant (kQ) of singlet oxygen (1O2) by α-tocopherol was performed in ethanol solution including four kinds of alkali and alkaline earth metal salts (NaClO4, Mg(C...

Recently, a new assay method for the quantification of the singlet oxygen absorption capacity (SOAC) of antioxidants (AOs) and food extracts in homogeneous organic solvents was proposed. In this study, second-order rate constants (kQ) for the reaction of singlet oxygen (1O2) with eight different carotenoids (Cars) and α-tocopherol (α-Toc) were measured in an aqueous Triton X-100 (5.0 wt %) micellar solution (pH 7.4, 35 °C), which was used as a simple model of biomembranes. The kQ and relative SOAC values were measured using ultraviolet–visible (UV–vis) spectroscopy. The UV–vis absorption spectra of Cars and α-Toc were measured in both a micellar solution and chloroform, to investigate the effect of solvent on the kQ and SOAC values. Furthermore, decay rates (kd) of 1O2 were measured in 0.0, 1.0, 3.0, and 5.0 wt % micellar solutions (pH 7.4), using time-resolved near-infrared fluorescence spectroscopy, to determine the absolute kQ values of the AOs. The results obtained demonstrate that the kQ values of AO...

(1,3-Dihalo-2-azulenyl)diphenylphosphines 2 [halogen = Cl (a), Br (b)] and homologous bis(1,3-dihalo-2-azulenyl)phenylphosphines 4 have been synthesized, and the effect of the nonalternant azulenyl...

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.

Four kinds of 1:1 salts of 3-(4- and 3-alkyl-pyridinium)-1,5-diphenylverdazyl (alkyl = ethyl and methyl) radical cations with the Ni(dmit)2 anion ([p-EtPyDV]+[Ni(dmit)2]− (1), [m-EtPyDV]+[Ni(dmit)2...

Five kinds of (1:1) and (1:3) salts of 3-(4- and 3-alkyl-pyridinium)-1,5-diphenylverdazyl (alkyl = ethyl and methyl) radical cations with Ni(dmit)2 anion ([p-EtPyDV]+[Ni(dmit)2]− (1), [m-EtPyDV]+[Ni(dmit)2]− (2), [p-MePyDV]+[Ni(dmit)2]− (3), [m-MePyDV]+[Ni(dmit)2]− (4), and [ p - MePyDV ] + [ Ni ( dmit ) 2 ] 3 - ( 5 ) ) (dmit = 1,3-dithiol-2-thione-4,5-dithiolate) have been prepared, and the magnetic susceptibilities (χM’s) have been measured between 1.8 and 300 K. The χM of salt 1 can be well explained by a four-spin linear tetramer model ([p-EtPyDV]+–[Ni(dmit)2]−–[Ni(dmit)2]−–[p-EtPyDV]+) with an end exchange interaction 2J1/kB = −780 K and a central interaction 2J2/kB = −200 K. The formation of magnetic tetramer in salt 1 has been ascertained by the crystal structure analysis of 1. The χM of salt 2 was explained by the sum of the contributions from: (i) a dimer system (2J/kB = −320 K) due to Ni(dmit)2 anions and (ii) the one-dimensional (1D) Heisenberg ferromagnetic linear-chain system (2J kB = +2.5 K) due to verdazyl cations. The χM of salt 3 is similar to that of salt 1, suggesting a formation of magnetic tetramer in salt 3. The χM of salt 4 shows a broad maximum at Tmax = 100 ± 2 K, and can be explained by a 1D Heisenberg antiferromagnetic alternating-chain model with 2J1/kB = −165 K (alternation parameter α = J2/J1 = 0.6). The conductivity (σ) of salts 1, 2, 3 and 4 at 293 K was σ = 2.3 × 10−5, 1.1 × 10−3, 1.4 × 10−5 and 5.4 × 10−6 S cm−1 with an activation energy of EA = 0.28, 0.52, 0.21 and 0.33 eV, respectively. The (1:3) salt 5 (σ = 1.0 S cm−1, EA = 0.048 eV) showed three to five orders of magnitude higher conductivity than those of the (1:1) salts 1–4 at room temperature. All the (1:1) and (1:3) salts 1–5 are new molecular paramagnetic semiconductors.

A nonalternant organyl ligand derived from azulene, a 1,3-dichloro-2-azulenyl group, is introduced for the first time into the bismuth and antimony center. Conversion of the azulenylbismuthanes into the pentacoordinated difluorides by xenon difluoride promotes the π-polarization of the azulene nucleus, which is detected as a color change in solution as well as changes in the chemical shifts of the 13C NMR spectra. A similar tendency is observed in the antimony congeners. The X-ray crystallographic study of (1,3-dichloro-2-azulenyl)diphenylbismuth difluoride (20b) reveals that intermolecular π−π stacking takes place between the azulenyl groups through the interaction of the five-membered ring with the seven-membered ring. This may reflect the more polarized azulenyl group of the difluorides, which strengthens the stacking interaction.

Two kinds of iodide salts of 3-(4- and 3-methylpyridinium)-1,5-diphenylverdazyl radical cations ([p-MePyDV]+I− (1) and [m-MePyDV]+I− (2)) and four kinds of 1 ∶ 1 and 1 ∶ 2 salts of the same verdazyl radical cations with tetracyanoquinodimethanide (TCNQ) anion ([p-MePyDV]+[TCNQ]− (3), [m-MePyDV]+[TCNQ]− (4), [p-MePyDV]+[TCNQ]2− (5), and [m-MePyDV]+[TCNQ]2− (6)) have been prepared, and the magnetic susceptibilities (χM’s) have been measured between 1.8 and 300 K. Salts (1) and (2) behave as one-dimensional (1D) alternating and nonalternating Heisenberg antiferromagnets with exchange interactions of 2JI-II/kB = −171 ± 4 K (alternation parameters α = JI-III/JI-II = 0.5) and 2J/kB = −15.4 ± 0.9 K (α = 1), respectively. The χM of (3) follows the Curie–Weiss law with a Curie constant of 0.365 K emu mol−1 and a positive Weiss constant of +2.1 ± 0.2 K, indicating disappearance of a net magnetic moment due to the formation of strong spin pairs in TCNQ anion molecules. The χM of (4) shows a broad maximum at Tmax = 24 ± 1 K. The χM can be well reproduced by the sum of the contributions from i) a 1D Heisenberg antiferromagnetic alternating-chain system with 2J1/kB = −47 ± 2 K (α = J2/J1 = 0.9) and ii) a dimer system with 2J/kB = −636 ± 30 K. The susceptibilities of (5) and (6) showed anomalous magnetic behavior that cannot be explained by a simple model. The separate contributions of the verdazyl cation and TCNQ anion subsystems to the total magnetic susceptibility of the salts were evaluated from measurements of the temperature dependence of the g-value. The 1 ∶ 1 salts (3) and (4) are insulators. On the other hand, the pressed pellet conductivity (σ) of the 1 : 2 salts (5) and (6) at 20 °C was σ = 8.1 × 10−3 and 2.9 × 10−2 S cm−1 with activation energy of EA = 0.092 ± 0.005 and 0.091 ± 0.005 eV, respectively. The two 1 ∶ 2 salts (5) and (6) are new genuine organic magnetic semiconductors.

2,2,4,4,6,6-Hexakis(4-pyridylmethoxy)-2λ5,4λ5,6λ5,-cyclotriphosphazene (PyPN) and 1,4-anthracenedicarboxylic acid (DCA) formed polymeric supramolecules through hydrogen bonding between carboxyl and pyridyl groups. Two supramolecular self-assemblies were obtained: crystals 1 composed of PyPN/DCA = 1 : 2 from DMSO solution, and crystals 2 composed of PyPN/DCA = 1 : 3 from DMF solution. The former is monoclinic, space group P21/n with a = 12.419 A, b = 24.10 A, c = 20.794 A, β = 93.53°, V = 6212 A3, Z = 4. The X-ray analysis showed that the complementary hydrogen bonding occurs with two DCA molecules, one on each side of the phosphazene ring of PyPN, to give a novel assembly with polymeric structure. The self-assembly obtained from DMF solution seems to take a cylindrical structure composed of an alternating sequence of one PyPN and three DCA molecules and to be packed into a hexagonal arrangement, as suggested by X-ray diffraction data. These results and the inclusion behaviors of the solvent molecules into...

Acid-catalysed hydrolysis kinetics were studied for 14 cobalt(III) carbonato complexes involving the title five at oxonium ion concentration of 0.01-1.0 M, ionic strength of 2.0 (NaClO 4 ) and 15-45°C (M=mol dm m 3 ). Preprotonation constant, about 1 M m 1 , was estimated from a non-linear acidity dependence of an experimental rate constant for the ring-opening of the didentate hydrogencarbonato intermediate. Acidity constant, 0.003-0.7 M, and basicity constant, 0.1-0.9 M m 1 , of the ring-opened aquahydrogencarbonato intermediate were estimated from an acidity dependence of an experimental rate constant for the decarboxylation. Concerning the widely ranging ring-opening rate constants (0.05-126 s m 1 at 25°C), we demonstrate labilizing effects of a reduced charge and of small tetrakis(amine) ligand, correlating with a high activation entropy, as well as of the trans five-membered chelate correlating with a low activation energy. The charge effect may be understood by the solvational change during the dis...

Three kinds of (1:1) salts of TCNQF 4 anion with 3-(4-trimethylaminophenyl)-1,5-diphenyl-6-oxo-verdazyl radical cation [1 + ] and its mono-methyl [2 + ] and di-methyl [3 + ] derivatives have been p...

Four kinds of (1:1) and (1:2) salts of 3-(4- and 3-ethyl-pyridinium)-1,5-diphenylverdazyl radical cations with tetracyanoquinodimethanide (TCNQ) anion ([p-EtPyDV]+[TCNQ]− (1), [m-EtPyDV]+[TCNQ]− (2), [p-EtPyDV]+[TCNQ]2− (3), and [m-EtPyDV]+[TCNQ]2− (4)) have been prepared, and the magnetic susceptibilities (χM) measured between 1.8 and 300 K. The values of χMT at 300 K are 0.437, 0.383, 0.620, and 0.482 K emu mol−1 for the salts (1), (2), (3), and (4), respectively, and decrease by lowering the temperature. The χM of the salt (2) follows the Curie–Weiss law with a Curie constant of 0.374 K emu mol−1 and a negative Weiss constant of −2.4±0.2 K in the temperature region 1.8–300 K, indicating disappearance of a net magnetic moment due to the formation of strong spin pairs in TCNQ anion molecules. The χM of the salt (3) shows a broad maximum at T max = 118 ± 2 K and can be well explained by a singlet–triplet equilibrium model with 2 J / k B = - 190 K The χM of the salt (4) shows a broad maximum at T max = 9.3 ± 0.5 K The χM can be well reproduced by the sum of the contributions from: (i) a one-dimensional (1D) Heisenberg antiferromagnetic alternating-chain system with 2 J / k B = - 15.2 K (alternation parameter α=J2/J1=0.4); and (ii) the dimer system with 2 J / k B = - 741 K The magnetic property of (4) was discussed based on the results obtained by crystal structure analysis of (4). On the other hand, the susceptibility of the salt (1) showed anomalous magnetic behavior that cannot be explained by a simple model. The (1:1) salts (1) and (2) are insulators. On the other hand, the pressed pellet conductivity (σ) of the (1:2) salts (3) and (4) at 20°C was σ=6.9×10−2 and 1.5×10−3 S cm−1 with activation energy EA=0.072 and 0.25 eV, respectively, showing the property as semiconductor. The two (1:2) salts (3) and (4) are new, genuine organic magnetic semiconductors.

10-Phenoxyphenothiabismine 5,5-dioxide (2a) and related compounds 2b,c, the first example of an air-stable aryloxybismuthane whose bismuth−oxygen bond is not incorporated into a ring system, were synthesized and fully characterized. Substitution of the OAr group in 2 by phenols in solution revealed two substitution tendencies. The substitution with 2-methoxyphenol proceeded preferentially due to intramolecular coordination of the 2-methoxy oxygen atom with the bismuth atom in 10-(2-methoxyphenoxy)phenothiabismine 5,5-dioxide (2b). Furthermore, the substitution is more favorable with more acidic phenols, which is in accord with the apicophilicity observed at an apical position in hypervalent compounds. 10-(4-Methoxyphenoxy)phenothiabismine 5,5-dioxide (2c) was found to form 10-(4-methoxyphenoxy)phenothiabismine 5,5-dioxide·4-methoxyphenol 1:1 complex (3) through hydrogen bonding between the OH group of 4-methoxyphenol and the aryloxide oxygen atom of 2c. Such complex formation may be the initial step of th...

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.

Copper(II) binuclear chromophores [{Cu(H 2 qpda)} 2 ] 4+ ( A ) and [{Cu(H 2 i qpda)} 2 ] 4+ ( B ) were isolated from an acidic aqueous solution of an equimolar H 2 L–CuSO 4 mixture, while H 2 iso-1-qpda gave no copper(II) binuclear complex [H 2 qpda=1,3-bis(quinoline-2-carboxamido)propane, H 2 i qpda=1,3-bis(isoquinoline-3-carboxamido)propane, H 2 iso-1-qpda=1,3-bis(isoquinoline-1-carboxamido)propane]. The crystal structures of A , B and the free ligand H 2 qpda were determined. The coordination structures in both A and B are trans -N 2 O 2 . The copper ions of both complexes are coaxially aligned and hence the heteroaromatic rings are highly stacked. ESR and optical absorption spectroscopies were employed to study their coordination and electronic structures. In the solution, A coexists with aquacopper(II) complex at any [H 2 qpda]/[Cu 2+ ] ratio, and with only a little [Cu(H 2 qpda) 2 ] 2+ mononuclear complex even at [H 2 qpda]/[Cu 2+ ]≥3.0. B coexists with [Cu(H 2 i qpda) 2 ] 2+ but without the aquacopper(II) complex at [H 2 i qpda]/[Cu 2+ ]>1.0. A and [Cu(H 2 O) 5 ] 2+ crystallize in an identical crystal isolated from the equimolar H 2 qpda–CuSO 4 aqueous solution. The trans -N 2 O 2 coordination structure also appears in [Cu(H 2 L) 2 ] 2+ chromophores. The instability of [Cu(H 2 qpda) 2 ] 2+ is ascribed to the trans -N 2 O 2 structure, having serious steric repulsion between the carbonyl oxygen and aromatic hydrogen atoms. Stable [Cu(H 2 i qpda) 2 ] 2+ is free from the steric repulsion. The existence of A possessing two such unstable trans -N 2 O 2 coordination units illustrates the important role of the π–π and hydrophobic interactions in forming the binuclear complex. The formation of B is always greater than that of the homologue [{Cu(H 2 ppda)} 2 ] 4+ [ C ; H 2 ppda=1,3-bis(pyridine - 2-carboxamido)propane]. Both Cu⋯Cu distance and interplanar separation between the stacking aromatic rings in B are significantly shorter than those in C . These results endorse the more effective π–π and hydrophobic interactions in B than C .

Using electron spin resonance (ESR) and visible spectroscopies, coaxially stacked binuclear copper(II) complexes of ω,ω′-bis(pyridine-2-carboxamido)alkanes in acidic aqueous solution (pH 3.8–5.0), H2peda (alkane = ethane), H2ppda (alkane = propane), and H2pbda (alkane = butane), were characterized. trans-1,2-Bis(pyridine-2-carboxamido)cyclohexane or trans-H2pcyhda (alkane = trans-1,2-cyclohexane) did not provide coaxially stacked binuclear complex, because of the lower conformational freedom at the HNCH-CHNH bond. The coaxially stacked structure causes π—π stacking between the pyridyl rings. The conformation of the propanediyl chain is gauche—gauche, while the ethanediyl and butanediyl chains contain an eclipsed conformation. The driving force for the formation of these binuclear complexes in acidic solution is intramolecular π—π stacking interaction between the pyridyl rings in concert with hydrophobic interaction. Although H2ppda gave crystals of a binuclear complex with many lattice water molecules, H2peda and H2pbda ligands provided crystals of copper(II) polymer complexes from the respective acidic solution. The trans-H2pcyhda ligand forms a copper(II) binuclear complex with open-chain structure in acidic solution. Crystal structures of the polymer complexes are also presented.

The crystal structure of the nitridochromium(V) complex [CrN(salophen)]·MeCN [H2salophen=N,N′-bis(salicylidene)-o-phenylenediamine] has been determined. The coordination geometry of this complex, similar to those of all the nitridochromium(V) complexes investigated so far, is square pyramidal with the nitride ion occupying the apex. The ESR parameters of the nitridochromium(V) complexes isolated so far were compared with one another to show an enormous expansion of the 3d electron cloud due to the strong CrN triple bonding. Moderate covalency in the in-plane bonds was also concluded. The nephelauxetic series of three types of the basal ligands is deduced to be salen≈salophen>bpb≈mebpb≈dmebpb>oep≈ttp (in nephlauxetic ratio) for the high-oxidation nitridochromium(V), H2salen=N,N′-bis(salicylidene)ethane-1,2-diamine, H2bpb=1,2-bis(pyridine-2-carboxamido)benzene, H2mebpb=1,2-bis(pyridine-2-carboxamido)-4-methylbenzene, H2dmbpb=1,2-bis(pyridine-2-carboxamido-4,5-dimethylbenzene, H2oep=2,3,7,8,12,13,17,18-octaethylporphyrin and H2ttp=5,10,15,20-tetra-p-tolylporphyrin.

A series of meta- and para-phenylene-bridged Bi(III)n and Bi(V)n compounds (n ≥ 2) have been synthesized. Reaction of Ph2BiX (X = Cl, OSO2CF3) with p-Li2C6H4, p-(BrMg)2C6H4, or p- and m-(Me2S·Cu)2C6H4 generated in situ from dibromobenzenes gave the corresponding para- and meta-phenylene-bridged Bin−bismuthanes, Ph2BiC6H4BiPh2 (2), Ph2BiC6H4Bi(Ph)C6H4BiPh2 (3), and Ph2BiC6H4Bi(Ph)C6H4Bi(Ph)C6H4BiPh2 (4), in 2−30% yields. Bin-bismuthanes 2−4 were oxidatively chlorinated by SO2Cl2 to yield the Bin-bismuth polychlorides 5−7, in which all pentavalent bismuth atoms bore three aryl groups and two chlorine atoms. Compounds 2−7 showed λmax at around 244−249 and 285−290 nm in the UV−vis spectra, suggesting that the phenylene bridges did not perturb significantly the σ- and π-transitions of the aromatic systems in these bismuth oligomers. Ortho-lithiation directed by the sulfonyl group was employed for the one-pot preparation of highly branched Bin-bismuthanes; successive treatment of Ar3Bi 9a with 3 equiv of t-BuLi...

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.

Hexakis(4-pyridylcarbinoxy)cyclotriphosphazene (PyPN) and terephthalic acid (TPA) self-assembled into polymeric supermolecules through hydrogen bonding between carboxyl and pyridyl groups. Two supe...

(4-Chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}iodobismuthane (3b), the first example of an optically pure bismuthane, was synthesized with exclusive stereoselectivity using Bi−N intramolecular coordination and the planar chirality of ferrocene. The variable-temperature 1H NMR spectra measured in the range from −50 to +50 °C in CDCl3 revealed that no epimerization takes place at the bismuth center. An X-ray crystallographic study demonstrated that the bismuth atom is diastereoselectively introduced into the substituted cyclopentadienyl ring and that the 4-chlorophenyl group occupies the exo position toward the iron atom. The absolute configuration around the bismuth atom was determined to be R. The longer intramolecular Bi−N distance of 3b [2.71(1) A] compared with those of chloro{2-[(R)-1-(dimethylamino)ethyl]phenyl}phenylbismuthane (1a,b) [2.55(2), 2.57(2) A, respectively] indicates a weaker Bi−N coordination in the ferrocene system. The specific rotation of 3b, [α]D23 −546 (c 1.0, CHCl3)...

The crystal structure of the nitridochromium(V) complex [CrN(salen)] (H2salen = N,N′-bis(salicylidene)ethylenediamine) has been determined. This complex crystallizes in the monoclinic system, space group P21/c, a = 9.575(1), b = 12.322(3), c = 12.999(2) A, β = 103.57(1)°, V = 1490.8(5) A 3 , Z = 4; final R2 = 0.059 (R = 0.054), wR2 = 0.082 (wR = 0.044) for 1935 observed reflections (I⩾1.5σ(l)). The coordination geometry is square pyramidal with an N2O2 donor set (LN202) in the basal plane and the nitride ion at the apex. The UV-Vis spectra of the complex have been re-measured in several solvents and exhibited a d-d band maximum around 540 nm (ϵ ≈200 M−1cm−1). This is the first example of an observed d-d band among the nitridochromium(V) complexes isolated so far. The ESR spectra have been also re-measured in more detail. The ESR parameters have been compared with those of the [CrN(LN4)] complexes and a remarkable nephelauxetic effect of the 3d sub-shell in comparison with the 3s sub-shell is indicated for the nitridochromium(V) complexes.

Obvious differences in 3dz 2 ground-state ESR spectra observed at 77K were detected between a powder sample of Cu(II) doped in [Mg(B15C5)(H2O)2](ClO4)2 single crystal and a Cu(B15C5) complex in 60% HClO4. An X-ray diffraction analysis of [Mg(B15C5)(H2O)2](ClO4)2 demonstrated that the complex takes on a seven-coordinate pentagonal bipyramidal geometry and the axial ligands are also H2O molecules, which is similar to [Cu(B15C5)(H2O)2](ClO4)2. Differences in ESR spectra are qualitatively explained as being due to changes in coordination bond distances and angles for both cases, based on vibronic interaction theory. The ground-state Kramers doublet wavefunctions were calculated and reveal an increase of admixture of 3dx 2_y 2 and 3dxy orbitals into a 3dz 2 ground-state for the Cu(II) ion doped in the crystal.

3,4-Bis(methylthio)-and 3,4-dichalcogeno-8,9-dihydro-7,10-dithiafluoroanthene and 3,4-bis(methylthio)- and 3,4-dithio-7,10-dithiafluoroanthene were synthesized as novel donor components for organic conductors. These donors showed low oxidation potentials, and intermolecular van der Waals interaction between the sulfur atoms was observed by X-ray crystallographic analysis. The radical cation salts and charge transfer complexes of the donors with various inorganic and organic acceptors were prepared either by electrocrystallization in the presence of tetraalkylammonium salts or by recrystallization of the mixture of donors and acceptors. Some of these radical cation salts showed good electrical conductivities.

ESR and optical absorption measurements were performed for six-coordinate Fe(III)TPP-butyl peroxide complexes formed in the reaction system composed of Fe(III)TPPCl, NaOCH 3 and t- or n-butyl hydroperoxide. The presence of four paramagnetic iron complexes was detected in the reaction system. Based on the spectroscopic parameters, the spin state and the axial ligand of these species were deduced as follows: Fe(III)TPP-(HOCH 3 )( − OCH 3 ) ( A ), -( − OCH 3 ) 2 ( B ), ( − OCH 3 )( − OO-butyl) ( C ), -( − OO-butyl) 2 ( D ) coordination reactions of t- and n-butyl hydroperoxide and complexes A and B were monitored on changing the molar ratio of [t- or n-butylperoxide]/ [Fe(III)TPPCl]. The observed spectral changes justified that complexes A and B were successively changed to complex D through complex C . The concentration of these four paramagnetic complexes was estimated by means of the duplicate integration of the observed ESR spectra at 4.2 K. The molar distribution of complexes A, B, C and D was simulated by taking into account the formation constants relating to the generation of the peroxide complexes C and D . By comparison of the formation constants, the possible mechanisms for Fe(III)TPP-peroxide complex formation were discussed.

A new example of a racemate showing unusual enantiomeric resolution phenomenon, in which simple recrystallization of the racemate leads to remarkable enantiomeric enrichment of either enantiomer up to 100% ee in the mother liquor, has been found. This compound is (±)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenylcarbamoyl]-ethyl]dimethylsulfonium p-nitrobenzenesulfonate [EtOCH2CH(OH)CH2OC6H4NHCOCH2CH2SMe2+O2NC6H4SO3−] [(±)-SN]. By repeating recrystallization of (±)-SN and the resulting deposited crystals successively and collecting the resulting enantiomerically enriched mother liquors with the same chirality sense, highly efficient enantiomeric resolution of the racemate into its separate enantiomers has been accomplished. The relationship between the occurrence of this enantiomeric resolution phenomenon and the crystal properties has been investigated with respect to SN and its aryl- and alkylsulfonate derivatives. The mode of enantiomeric resolution of (±)-SN was similar to that of para-substituted benzenesulfonate derivatives (±)-ST (4-MeC6H4SO3−) and (±)-SC (4-ClC6H4SO3−) previously reported, whereas the unsubstituted derivative (±)-SB (C6H5SO3−) and alkysulfonate derivatives (±)-SO (n-C8H17SO3−) and (±)-SM (CH3SO3−) did not show such an enantiomeric resolution phenomenon. The crystalline form of the former racemates that underwent the enantiomeric resolution was racemic compounds, while the latter were mixed crystals (solid solutions) composed of the respective optical antipodes. Chirality 9:220–224, 1997. © 1997 Wiley-Liss, Inc.

Treatment of tris-(2-alkoxyphenyl)bismuthanes 1 with iodosylbenzene in methylene dichloride at 40 °C led to none of the expected bismuthane oxides 2 but, quite unexpectedly, gave tetrakis-(2-alkoxyphenyl)bismuthonium chlorides 3 in moderate to good yields. In some cases, bismuthonium formates 4 accompanied the main reaction products. Similar treatment in benzene in the presence of benzyl bromide, ethyl bromide, or 2,2,2-trifluoroethyl iodide led to the corresponding bismuthonium bromides 7 and iodides 8. Through anion exchange, a variety of bismuthonium salts including formate 4, tetrafluoroborate 11, toluene-p-sulfonate 12, bromide 7, iodide 8 and perchlorate 13 were prepared from the salt 3 in good yields. In contrast to the known tetraphenylbismuthonium salts, all of these new bismuthonium salts exhibited high thermal stability. The molecular structure of compound 7a was elucidated by X-ray analysis, where the four neighbouring oxygen atoms are found to surround the bismuth atom tetrahedrally via a weak through-space interaction with the metal, making the bismuth centre less susceptible to nucleophilic attack of the halide anion.

p-Terphenoquinone analogues containing a quinonoid type of tellurophene skeleton in the central position have been prepared with a view to developing a new type of organic pnotoconductive materials having amphoteric redox properties. X-ray structure analysis showed that each molecule exhibited an asymmetric boat conformation owing to the bent structure of the whole ring system and the opposite twisting of two terminal rings. The molecular packing manner in the crystals depends on the substituents on the terminal quinonoid rings. These compounds were electrically amphoteric and afforded radical cation salts and CT complexes by electrochemical or chemical oxidation or by the reaction with an appropriate electron acceptor, respectively. Preliminary experimental results on the photoconductive properties of the neutral compound along with the electrical and magnetic properties of the radical cation salts and CT complexes are described.

The cation radical (CR) and charge transfer (CT) salts of 7,10-dithiafluoroanthene with various inorganic and organic acceptors were prepared either by electrocrystallization in the presence of tetraalkylammonium salts or recrystallization of the mixture of donor and acceptors. The structures of these CR and CT salts were determined by X-ray crystallographic analysis and the conductivities of those salts were measured by a four probe method using compaction pellets.

By recrystallization of certain racemic compound (ST), racemic compound crystals, mixed crystals of two enantiomers, or a mixture of these two types of crystals were obtained, depending on the recrystallization conditions employed. Their crystal forms were determined by X-ray diffraction of the single crystals and powdered materials. The space group and lattice parameters of the mixed crystals were identical with those of the enantiomeric crystals. This polymorphism of ST crystals would be ascribed to the small difference in the thermodynamic stability between the enantiomeric and racemic crystals. The physicochemical properties of ST are described, too.

A new type of α-asymmetric bicyclic nitroxides were synthesized by three electron reduction of certain homoallylic nitroenones followed by the reaction with nitro-substituted benzoyl chlorides. Some nitroxides thus obtained turned out to exist as a conglomerate (racemic mixture), an equimolecular mixture of two crystalline enantiomers, and hence induced spontaneous optical resolution upon recrystallization. The relationship between the formation of conglomerates and their molecular and crystral structures is described, together with the preliminary results of their paramagnetic susceptibility mesurements.

The crystal structure of dichloro(5,10,15,20-tetraphenylporphinato)phosphorus(V) chloride dichloromethane solvate has been determined by X-ray diffraction at ambient temperature. A saddle shape of the meso-tetraphenylporphinate disc is attributed to marked S4 deviation from planarity. The mode of the torsion of four phenyl rings around the CC bonds connecting these rings to the respective meso carbon atoms are also of S4 character. The phosphorus atom lies just in the mean plane of the porphinate nitrogen atoms. The PN bond distances range from 1.804(3) to 1.821(3) A, which are shorter than those observed in [P(OH)2(tpp)]+ (1.870–1.916 A), while the axial PCl bond distances [2.149(1) and 2.153(1) A] are significantly longer than the distance expected for the normal covalent PCl bond (2.10 A). This phosphorus porphyrin reveals characteristic features peculiar to the structure of metalloporphyrins with the smallest-sized central cations.

The crystal structure for one of crystal modifications of the title compound (taa) has been determined by X-ray diffraction at room temperature. The crystal system is monoclinic with a space group of P21/a : a=14.926(2), b= 5.2342(8), c=19.570(2)A, β=112.195(7)°, Z= 4. The final R factor is 0.033 for 1 443 observed reflections to 270 variables. The crystals recrystallized from xylene have been proven to be a different crystal modification from those obtained by vacuum sublimation at 250 °C. In the present crystal, two independent molecules are located on the crystallographic centres of symmetry. Each of them shows positional disorder at the amino hydrogen atoms. This modification does not exhibit the alternation of the bond lengths in the 1,3-propanediiminato linkage beyond the limit of ΔI < 3σ(I), which is the case for a previously reported crystal modification. These findings lend support to dynamic imine-enamine tautomerization rather than static disorder. The difference Fourier map suggests a double-minimum potential for the proton tautomer ism. Rapid tautomerization in [2H8]toluene solution can be observed by 1H NMR spectroscopy down to –90 °C, just above the melting point of the solvent.

An electron paramagnetic resonance (EPR) study has been carried out on a single crystal of trans-[VOCl2(H2O)2](18- crown-6)·2H2O or adduct of trans-diaquadichlorooxovanadium(IV) with 1,4,7,10,13,16-hexaoxacyclooctadecane (abbr. 18C6) at ambient temperature. This crystal belongs to a centric triclinic space group, and the chromophore and crown ether alternate to form a magnetically diluted vanadyl system. The EPR study has revealed the rhombic spin Hamiltonian parameters gz = 1.952(1), gx = 1.985(2), gy = 1.990(3), ∣Az∣ = 18.8(3), ∣Ax∣ = 7.6(3) and ∣Ay∣ > 5.5 mT, where the z, x and y principal axes are along the VO and nearly along the VOH2 and VCl bonds, respectively. Errors of these parameters are large, especially in Ay, owing to many broad hyperfine linewidths resulting in overlapping. A negative sign is suggested for all the principal A values. Three d-d* transitions, dxy→dyz (12.9 kcm−1), dxy→dyz (15.2) and dxy→dx2−y2 (17.0), and a charge-transfer transition, a1(related to dx2−y2)→a2(dxy) (27–28 kcm−1) from the acetone solution, were assigned. The trans-[VOCl2(H2O)2] species is not dissociated in acetone and 2-propanol solution, but the chloro ligands are substituted with aqua ligands when there is a lot of water in the solution.

The first 7,10-Dithiafluoroanthene has been prepared from acenaphthenone in three steps, via ring expansion reaction of acenaphthenone ethylenedithioacetal. It was shown to be good π-donor and form highly conducting cation radical salts with PF 6 − . X-ray crystallographic analysis of the salt showed columnar stack structure of donors and the salt showed high electrical conductivity at room temperature.

The title complexes trans (O)-(Co(aeida)Cl(H 2 O)] ( A ) and mer (N)-[CoCl (i-dtma)(H 2 O)] ClO 4 ( B ) crystallize as a conglomerate (H 2 aeida = N-(2-aminoethyl)-N-(carboxymethyl)glycine, Hi-dtma = N,N-bis(2-aminoethyl)glycine). The X-ray crystallographic analysis shows that single crystals of A and B are chiral. Although the conglomerate formation of either A and B was not observed in the crystal morphology under a microscope, it was confirmed by the Weissenberg photography method. In A , the chirality originates from the δ or λ conformation of the ethylenediamine chelate ring. In B it originates from the fact that chiralities due to the δ and λ conformation of the two ethylenediamine chelate rings in the complex do not cancel out, owing to the asymmetry derived from the rotational configuration of the aqua ligand. These chiral molecular configurations are closely related with intermolecular hydrogen bonds in the crystal.

The crystal structures of molecular adducts of vanadyl complex of trans-[VOCl2(H2O)2] with 15-crown-5 (15C5), benzo-15-crown-5 (B15C5) have been studied by X-ray diffraction at ambient temperature. The adduct of the same complex with 18-crown-6 (18C6) recrystallized from a solvent different from that previously reported, has been also re-refined and the unresolved chloro position has been resolved into two disordered positions. The ClVCl bond angles in the 15C5 and B15C5 adduct are 143° and 145°, respectively, which are smaller than the OVO bond angles of 153° and 154°. There appear eclipsed type H2O-VCl2 conformations in all the adducts. These observations can be ascribed to the steric repulsion between the chloro ligands and aqua hydrogen atoms as well as to the coulombic repulsion between the chloro and oxido ligand. The crystals are composed of adduct polymers with 1 : 1 stoichiometry in which the chromophore and crown ether alternate along the polymer axis. The polymers are formed by hydrogen bonding between the aqua ligand and the oxygen atoms on the crown ring. The crown ethers adopt invariably all-gauche CC conformation. The OC bonds are of trans conformation except for a gauche OC bond in 15C5. ESR parameters of trans-[VOCl2(H2O)2] observed for the 15C5 adduct powder are also presented.

A novel π-donor, 1,2:5,6-bis(ethylenedithio)pyracylene (2), was prepared by dithioacetalization of 1,5-pyracenedione with 1,2-ethanedithiol followed by ring expansion on treatment with tellurium tetrachloride. 2 showed two reversible low oxidation potentials by cyclic voltammetry. Single crystal X-ray analysis of 2 revealed unique three dimensional donor networks.

A series of five copper(II) complexes with four geometrically isomeric ligands of 1,4,7,10-tetrabenzyl-2,5,8,11-tetraethyl-1,4,7,10-tetraazacyclododecane and with (2R,5R,8R,11R)-2,5,8,11-tetraethyl-1,4,7,10-tetraazacyclododecane has been investigated by means of ESR, CD and MCD in solution. X-ray studies reported separately had shown that the [CuN4Cl] chromophores were distorted to varying extents from square pyramidal to trigonal bipyramidal geometry. The stability and rigidity of the molecular structure have enabled us to carry out a complementary study of the crystalline state and solution chemistry. The ground state Kramers doublets varied from 3dx2−y2 to 3dz2 type with increasing distortion around the copper ion. The orbital sequence of the 3d1 positive hole, dx2−y2

The crystal structure of the title radical has been determined by X-ray diffraction at ambient temperature. The crystal system is monoclinic with a space group of Cc: a= 33.204(4), b= 9.391(1), c= 15.290(1)A, β= 101.223(7)°, Z= 8. The final R factor is 0.035 for 2623 observed reflections. There are two crystallographically independent molecules constituting a pair of atropisomers. Two fluoren-9-yl groups and a chlorophenyl moiety are arranged in a propeller shape. The range of the torsion angles of the fluorenyl blades is 25°∼ 33°, and that of the chlorophenyl blades is 55°∼ 59°. The electron-spin exchange pathways are discussed based on the McConnell's spin-density Hamiltonian. The exchange-coupled neighbours are estimated to be z= 6, to which the highest TN among organic radicals can be attributed.

The crystal structures of two complexes of the 9-(9H-fluoren-9-ylidenephenylmethyl)-9H-fluoren-9-yl stable radical with benzene (BDPA–Bz) and acetone (BDPA–Ac) have been determined by X-ray diffraction at room temperature. They are an isostructure of a monoclinic system with a space group of P21/n. For BDPA–Bz, a = 9.502(2), b = 14.632(2), c = 19.452(2) A, β = 93.64(1)°, V = 2699(1) A3, Z = 4, Dx = 1.220 g cm−3. For BDPA-Ac, a = 9.657 (1), b = 14.675(2), c = 18.812(2) A, β = 95.388(9)°, V = 2654.4(6) A3, Z = 4, Dx = 1.190 g cm−3. The final R values are 0.043 and 0.062 for 5.47 and 3.93 ratio of the observed reflections versus the parameters for BDPA–Bz and BDPA–Ac, respectively. The BDPA molecules in both crystals have the same propeller shape with an approximated C2 symmetry. The molecular packing of these crystals does not show a one-dimensional stacking, in spite of the magnetic one-dimensionality elucidated by the magnetic susceptibilites. The exchange pathways are discussed based on the McConnell’s s...

The crystal structures of [Co(hfac)(en) 2 ](ClO 4 ) 2 ( I ) and β-[Co(hfac) (trien)](ClO 4 ) 2 ( II ) have been determined by X-ray diffraction at ambient temperature, where Hfac = hexafluoro-2,4-pentanedione, en = ethylenediamine and trien = 1,8-diamino-3,6-diazaoctane. The relative configuration of the cation in II is rel -Δ- RR . Their molecular structures are compared with those previously reported for [Co(hfacOH)(en) 2 ] + , [Co(hfacOH 3 )(en) 2 ] + and β-[Co(hfacOCH 3 )(trien)] + , in which an OH − or OCH 3 − anion is covalently combined with one of the carbonyl carbon atoms on the hfac ligand. The quasiaromaticity of the coordinating hfac ligand in I and II was structurally characterized.

A novel 2,3,8,9-tetrahydro-1,4,7,10-tetrathiachrysene (7) was conveniently prepared by dithioacetalization of 1,5-decalinedione with 1,2-ethanedithiol followed by ring expansion and aromatization on treatment with tellurium tetrachloride. Electrocrystallization by anodic oxidation of 7 in the presence of suitable electrolytes gave the radical cation salts, (7)2ClO4 or (7)2BF4 with a considerable high electrical conductivity (0.4–12 Scm−1) and good thermal stability. Single crystal X-ray analyses revealed a segregated stack structure for 7 and anions in these salts.

Treatment of triarylbismuth difluorides 1 with silyl enol ethers 2 in the presence of BF3·OEt2 gives (2-oxoalkyl)triarylbismuthonium tetrafluoroborates 3 as a stable crystalline solid, the bismuth centre of which has been found by X-ray analysis to possess a tetragonal geometry. The 2-oxoalkyl moiety of compound 3 couples with enolates and thiolates to afford the corresponding triketones 4 and α-thioketones 6, respectively.