bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study of the Inosine–Sodium Hydroxide–Water and Inosine–Potassium Hydroxide–Water Systems
Authors: Suzuki Yoshihisa , Toki Tadao 
Published: July 2006

Abstract
Solubility data have been obtained for the inosine–NaOH–H2O and inosine–KOH–H2O systems at 30 °C. Two different solid phases of the potassium salt of inosine (C10H11N4O5·K·H2O and C10H11.5N4O5·0.5 K·0.5 H2O) were found in the latter system, while only one solid phase of the sodium salt of inosine (C10H11N4O5·Na·2.5 H2O) was found in the former system. The hemi-potassium salt of inosine is incongruent and is decomposed by pure water, whereas the mono-alkaline-metal salts are stable. The solubilities of the two mono-alkaline-metal salts of inosine in water were determined at 0–50 °C and formulated as follows:
Na-salt, logS & = 0.01359·t+0.3997
K-salt, logS & = 0.00733·t+1.6513
where S represents the gram weight of the anhydrous salt per 100 g of water. The X-ray powder diffraction data of the above three salts are given.
Photoelectron Spectra of Substituted Benzenes
Authors: Kobayashi Tsunetoshi , Nagakura Saburo 
Published: July 2006

Abstract
Photoelectron spectra were measured in the region between 6 and 21 eV for aniline, N,N-dimethylaniline, phenol, anisole, benzonitrile, acetophenone, nitrobenzene, and their methyl derivatives. The observed spectra were interpreted in terms of their MO’s obtained by the CNDO/2 and EHMO methods, the methyl-substituent effect and the steric hindrance effect being considered. Both effects are essential for the reliable assignment of the observed photoelectron spectra. We found a general tendency that the interaction of the doubly degenerate highest occupied orbitals (e1g) of the benzene ring with the highest occupied orbital of a substituent group is important for the interpretation of the observed lower energy (7∼12 eV) bands. The only exceptional case is the nitrobenzenes in which the lowest vacant orbital of the substituent group is rather close to the highest occupied orbitals of the benzene ring and the interaction between them is important. The effects of the substituent groups upon the observed photoelectron spectra are classified into four types.
Formation of Long-Lived Highly-Excited States of H, C, and N Atoms by Low-Energy Electron Impact on CH3CN
Authors: Shibata Takemasa , Fukuyama Tsutomu , Kuchitsu Kozo 
Published: July 2006

Abstract
Long-lived excited states of hydrogen, carbon and nitrogen atoms (H**, C** and N**) produced by the electron bombardment of CH3CN in the energy range from 20 to 100 eV were detected as H+, C+ and N+ ions as a result of collisions with H2O. The appearance potential of H+ was observed to be about 3 eV lower than the threshold energy for He+ formed from He** with H2O (about 24.6eV). The C+ threshold energy was about the same as that for He+, while that for N+ appeared to be a few eV higher. This suggests that the H** species is mainly responsible for the formation of CH3CN− due to the electron bombardment of CH3CN observed by Sugiura and Arakawa, at least in the energy region below the He** threshold energy.
The Basic Compound Produced in the γ-Radiolysis of Liquid Nitrogen Containing Hydrocarbons
Authors: Ishizaki Kaname , Sato Shin 
Published: July 2006

Abstract
The G-values of the basic compounds produced in the γ-radilysis of liquid nitrogen containing hydrocarbons have been measured by Conway’s method. The concentration dependence of the G-values suggests that the basic compounds observed are the products of the reaction between nitrogen atoms and the hydrocarbon radicals eventually formed in the system.
ESR Spectra of Radicals during Photolysis of Chloranil in Solutions
Authors: Yoshida Hiroshi , Kambara Yoshihiko , Rånby Bengt 
Published: July 2006

Abstract
ESR spectra were recorded during photolysis of chloranil in 2-propanol, ethanol, methanol and benzene at room temperature. The spectra observed from solution in alcohols are identified as due to neutral seqmiuinone radical. It is also suggested that excited chloranil abstracts a hydrogen from benzene.
Phase Diagrams of the Binary Systems of Some Metal β-Diketonates
Authors: Yoshida Isao , Kobayashi Hiroshi , Ueno Keihei 
Published: July 2006

Abstract
Phase diagrams of the binary systems consisting of some unchanged β-diketone chelates were determined. A combination of the chelate compounds which had the same coordination structures gave a mixed crystal system, and that of different coordination structures gave a eutectic system.
Electron Pairing Interaction and Electronic Spectra of Linear Polyene
Authors: Basu Sadhan 
Published: July 2006

Abstract
Assuming the pairing interaction which arises in Hartree-Fock-Bogolyubov formulation in manyelectron system, to be due to attraction between two electrons of opposite spin it has been shown that the longest wavelength singlet transition in linear polyenes will show convergence limit while the corresponding triplet transition will not.
Photochemistry of Acetophenone and Acetaldehyde in Ether Solvent —Formation of Diastereoisomeric Alcohols
Authors: Tokuda Masao , Hasegawa Miki , Suzuki Akira , Itoh Mitsuomi 
Published: July 2006

Abstract
Irradiation of acetophenone and acetaldehyde in tetrahydrofuran or diethyl ether gave the following diastereoisomeric alcohols, 1-phenyl-1-(2-tetrahydrofuryl)ethanol, 1-(2-tetrahydrofuryl)ethanol, 2-phenyl-3-ethoxy-2-butanol and 3-ethoxy-2-butanol.
ESR Study of γ-Irradiated Silk : Effect of Oxygen
Authors: Yoshioka Hisashi , Koide Naoto , Higashide Fukuji 
Published: July 2006

Abstract
The ESR spectra of silk γ-irradiated in a vacuum showed a doublet at room temperature and at −196 °C. The doublet turns to a singlet at g=2.006 by admission of O2. This is explained in terms of the formation of peroxide radicals.
The Circular Dichroism and Magnetic Circular Dichroism Spectra of Bis(stilbenediamine) nickel(II) Complexes
Authors: Arakawa Sumio , Nozawa Tsunenori , Hatano Masahiro 
Published: July 2006

Abstract
The temperature dependence of the absorption and circular dichroism spectra for [Ni((+)-stien)2](ClO4)2 is indicative of the equilibrium between the square planar (yellow) and tetragonal (violet) species in acetone solutions. On the other hand, the square planar species is predominant in a methanol solution, even at room temperature, in the case of [Ni(meso-stien)2](ClO4)2. The Cl− as a counter anion favored an equilibrium slightly displaced to the tetragonal species. The analysis of the CD and MCD bands suggests an ordering of the d-orbital energy levels of dx2–y2&gt;&gt;dz2&gt;dxz,dyz&gt;dxy.
The Photochemical Reaction of Benzofuran Derivatives with Benzophenone or Benzaldehyde
Authors: Kawase Yoshiyuki , Yamaguchi Seiji , Ochiai Hirokazu , Horita Hisanori 
Published: July 2006

Abstract
The photochemical reaction of 2-methyl-, 2,3-dimethyl-, 2,3-butano-, and 2-hydroxymethyl-benzofuran with benzophenone gave the corresponding oxetanes in yields higher than, or comparable to, those in the case of unsubstituted benzofuran, but in lower yields than in the cases of 3-methyl- and 2-isopropyl-benzofuran. The oxetanes were also produced by the reaction of 2-methyl-, 2,3-dimethyl-, and 2,3-butano-benzofuran with benzaldehyde, but these yields were not so high because of their instability. The reaction of 2-methoxycarbonyl-and 2-cyano-benzofuran with benzophenone or benzaldehyde gave dimers of the benzofurans, as in the case of 2-phenylbenzofuran.
Superacids and Their Derivatives. VI. Kinetics of the Cationic Ring-Opening Polymerization of Tetrahydrofuran Initiated by Ethyl 2,4,6-Trinitrobenzenesulfonate
Authors: Kobayashi Shiro , Nakagawa Tamotsu , Danda Hidenori , Saegusa Takeo 
Published: July 2006

Abstract
Ethyl 2,4,6-trinitrobenzenesulfonate (“trinitate”, EtOTn) was found to induce the ring-opening polymerization of tetrahydrofuran (THF). Kinetic studies of the THF polymerization by EtOTn initiator were carried out in CH2Cl2 solution by NMR spectroscopy. The instantaneous concentrations of the counteranion of the propagating oxonium species (1) and monomer were directly determined at the same time by the NMR measurement. The rate constants of initiation (ki) and propagation (kp(i)) due to 1 were obtained. Upon the view of kp(i) values with various initiators, it was concluded that the kp(i) values are changed significantly depending on the nature of the counteranion.
Hetera-p-carbophanes. IV. The Effect of Rigidity on the Chemical Shifts of Protons in Ansa Chains and Barriers to Rotation of Dioxadioxo[n]paracyclophanes
Authors: Sakamoto Kazuhiko , Oki Michinori 
Published: July 2006

Abstract
A series of dioxadioxo[n]paracyclophanes with or without methyl groups at the benzene ring were prepared and their PMR spectra compared with those of open-chain analogs as well as with those of paracyclophanes. Rigidity of the ansa chain was found to be an important factor in determining the chemical shifts of the ansa chain protons in addition to the ring current effect. Measurement of the PMR spectra at various temperatures revealed that the chemical shifts of the benzylic protons drifted to a small extent according to temperatures and the phenomenon was attributed to the change of solvation. Barriers to rotation of the aromatic rings in 615 and 616 were obtained as 23.3 and 11.0 kcal/mol, respectively. The barrier was discussed from the stand point of rigidity of the ansa chain.
The Crystal and Molecular Strucure of Arabinofuranosyladenine Hydrochloride
Authors: Hata Tadashi , Sato Sadao , Kaneko Masakatsu , Shimizu Bunji , Tamura Chihiro 
Published: July 2006

Abstract
Crystals of arabinofuranosyladenine hydrochloride are monoclinic, space group P21 with a=6.47, b=15.56, c=6.87 Å, and β=111.6°. Intensity data were collected on a four-circle diffractometer with Mo-Kα radiation. The structure was solved by means of Patterson and Fourier methods and refined using block-diagonal least-squares technique. The final R-factor for 1681 observed reflections is 4.5%. The sugar conformation is C3′-endo and the C(5′)–O(5′) bond is gauche to both C(4′)–O(1′) and C(4′)–C(3′). The torsional angle about the glycosidic C–N bond is anti, with χCN=29.3°. The hydrogen-bond scheme is similar to those found in several salts of nucleosides and deoxynucleosides.
Quenching of Excited Mercury Atoms(63P1 and 63P0) in Molecular Collisions
Authors: Horiguchi Hiroyuki , Tsuchiya Soji 
Published: July 2006

Abstract
The lifetime of Hg(63P0) in a gaseous mixture of Ar and N2 with quenching molecules (Q) was measured by monitoring the decay of the Hg(63P0) concentration following the excitation of Hg by pulsed 253.7 nm radiation. The lifetime in the absence of Q was reduced with the increase in the N2 pressure, being inversely proportional to the total pressure. This can be attributed to the deactivation by impurities involved in the gas and that by collision on the wall of the reaction cell. Deactivation due to impurities is dominant at a total pressure higher than 50 Torr. With quenchers in the mixture, the lifetime measurement gave the quenching cross-section of Hg(63P0). In addition, the measurement of the stationary concentration of Hg(63P0) made it possible to determine the rate for each of the processes 63P1→63P0 and 63P1→61S0. Based on the observed ratio, α=σ2(63P1→61S0)/σ2(63P1→61S0), quenching molecules are classified into three groups. The first group consists of N2O, O2, C2H4, C3H6, and C2H2 with α1.2 These molecules deactivate Hg(63P) to form their triplet states. The second group (CO, NO, H2, C3H8, i-,n-C4H10, and C(CH3)4) in which α≈4 makes the quenching via a short-lived complex (Hg–Q)*. The last group (CH4 and C2H6) has a value of α larger than 100. This is caused by a weak interaction between potential surfaces of Hg(63P)+Q and Hg(61S)+Q.
Metal Complexes of Amino Acids. V. μ-Aminocarboxylato Bi- and Tri-nuclear Complexes of Cobalt(III)
Authors: Yasui Takaji , Ama Tomoharu , Morio Hideki , Okabayashi Minahiro , Shimura Yoichi 
Published: July 2006

Abstract
Some new binuclear and trinuclear complexes containing μ-aminocarboxylato ligands, [(NH3)5Co(OCORNH2)Co NO2(acac)2](ClO4)2 (R=CH2, (CH2)2, and CH(CH3) for glycinato, β- and Dl-alaninato ligands) and [en2Co{(OCORNH2)Co NO2(acac)2}2]ClO4 (R=CH2 and (CH2)2), have been prepared and characterized on the basis of their elemental analyses, visible and ultraviolet absorption, infrared, and PMR spectra. It was concluded that the NH2 end of the μ-aminocarboxylato bridge occupies a coordination position trans to the NO2ligand, and the COO ends of two μ-aminocarboxylato bridges in the trinuclear complex occupy positions trans to each other.
Synthesis of Chelating Agents. XI. Synthesis and Chelating Behavior of Diaxial trans-Decahydronaphthylene-trans-2,3-dinitrilotetraacetic Acid
Authors: Yano Tairoku , Kobayashi Hiroshi , Ueno Keihei 
Published: July 2006

Abstract
Diaxial trans-decahydronaphthylene-trans-2,3-dinitrilotetraacetic acid (D[A.A]TA) was synthesized by carboxymethylation of diaxial trans-decalin-trans-2,3-diamine. The acid dissociation constants as well as chelate stability constants for alkaline earth metal ions were determined by potentiometric titration. The probable structure and chelating behavior of D[A.A]TA in aqueous solutions were discussed in reference to some related complexane ligands.
Heat of Evaporation of Polyoxyethylene Dodecyl Ethers
Authors: Nakamura Masao , Eda Kazuo , Kosiyama Kiiti 
Published: July 2006

Abstract
The heat of evaporation has been measured by the vapor pressure method for polyoxyethylene dodecyl ethers, C12H25(OC2H4)nOH (n=0, 1, 2, 3, and 4). It has been deduced that the polyoxyethylene chain is in a cyclic state in the vapor phase due to the intramolecular hydrogen bonding of the terminal OH group with an oxygen atom in the chain.
Field Ionization of Highly-excited Helium and Hydrogen Atoms Produced by Electron Impact
Authors: Shibata Takemasa , Fukuyama Tsutomu , Kuchitsu Kozo 
Published: July 2006

Abstract
The ionization of long-lived highly-excited helium atoms produced by electron impact was observed using an electrostatic field up to 8.3 kV/cm; the decrease of the He+ intensity produced by collisions of He** with H2O was measured as a function of the field strength using a mass filter. By use of the theory of Bailey et al., the principal quantum numbers of the highly excited He were estimated to range from 16 to 40. A similar but slower decrease of H+ due to H** atoms produced by electron impact on H2O was also observed.
The Properties of the Liquid Nitron Nitrate Membrane Electrode
Authors: Tateda Akira , Murakami Hiroko 
Published: July 2006

Abstract
The preparation and properties of the nitron nitrate nitrobenzene liquid membrane electrode, which is responsive to nitrate ions, are described. Special attention is given to the selectivity characteristics. High selectivities for NO3− over NO2−, C2H3O2−, Cl−, CrO42−, and SO42− were observed.
The Solid-State Spectra of Several Rhodizonates
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
The charge-transfer transitions between the anions were observed in the absorption spectra of alkalimetal rhodizonates in the solid state. Ammonium ions enhanced the electronic transition of this kind, whereas the solid-state spectrum of the barium salt was similar to the solution spectrum of the rhodizonate ion.
The Tautomerism of 2-Amino-5-nitrosotropone
Authors: Imafuku Kimiaki , Takata Yasuyoshi , Matsumura Hisashi 
Published: July 2006

Abstract
It was confirmed that 2-amino-5-nitrosotropone (II) exists in its tautomeric form (lIb) by the measurement of its dissociation constant and UV spectra.
Kinetic Studies on Olefin Epoxidation by Peroxo Molybdenum Complex (MoO(O2)2HMPT)
Authors: Arakawa Hironori , Morooka Yoshihiko , Ozaki Atsumu 
Published: July 2006

Abstract
Oxidation of olefin by peroxo molybdenum complex selectively yields epoxide at room temperature. The nature of the interaction of olefin with molybdenum and that of the peroxo molybdenum complex has been investigated in terms of coordination constant K of olefin and rate constant k2 of decomposition of the peroxo molybdenum-olefin complex, attention being paid to the substituent effect of olefin. The coordination constant increases with the extent of alkyl substitution on double bonded carbon, a tendency opposite to that on Pd(II), or Rh(I). The coordination state of olefin on molybdenum seems to differ from that on Pd(II) or Rh(I), for which π-back donation of metal d-electron is accepted to play an important role. The coordination complex on molybdenum is accordingly assigned to a π-complex with some electron donated to molybdenum. A remarkable steric effect of alkyl substituent is observed, disclosing a difference from the oxidation of uncoordinated olefin. Since k2 increases with K, revealing a similar substituent effect of olefin, the peroxo oxygen seems to be electrophilic, and the peroxo oxygen-molybdenum bond seems to be rather covalent than ionic, thus giving rise to epoxidation.
A Study of the Inosine–Hydrochloric Acid–Water and Inosine–Sulfuric Acid–Water Systems
Authors: Suzuki Yoshihisa , Toki Tadao 
Published: July 2006

Abstract
Solubility data have been obtained for the inosine–HCl–H2O and inosine–H2SO4–H2O systems at 5°C. The acid hydrolysis of inosine was satisfactorily prevented under the present conditions. Three new acid salts of inosine have been obtained: (1) C10H12N4O5·HCl·(l/2)H2O in the A-form, (2) C10H12N4O5·HCl·(1/2)H2O in the B-form, and (3) C10H12N4O5·H2SO4·2H2O. Their X-ray powder diffraction data are given. All of them are incongruent and decomposed by pure water; however, they are stable in air during storage at room temperature.
The Singlet-Triplet Absorption Spectra of Heterocyclic Amine iV-Oxides. II. Pyridine N-Oxide Derivatives
Authors: Yamakawa Masumi , Ezumi Kiyoshi , Mizuno Yoshiko , Kubota Tanekazu 
Published: July 2006

Abstract
The singlet-triplet absorption spectra of various pyridine N-oxide derivatives with an electron-donating substituent have been observed by applying the oxygen-intensification technique. The nature of the lowest triplet (T1 states of these N-oxides and the substituent effect on the T1 state of pyridine N-oxide have been discussed experimentally and theoretically. The T1 states of the above substituted pyridine N-oxides were assigned to a π-π* transition of a 3La (CT) nature; 3A1 for the p-substituted pyridine N-oxides. All the singlet-triplet absorption bands as well as the singlet π-π* bands recorded here show a blue shift in polar solvents; this phenomenon is also discussed. Last, the mutual relation between the contact charge-transfer bands and the singlet-triplet absorption bands, both enhanced by compressed oxygen, has been discussed, since, for pyridine N-oxides with p-N(CH3)2, p-OCH3, and m-NH2, we could not record the singlet-triplet absorption band clearly.
Synthesis of Chelating Agents. X. Chelating Behavior of 1,2-Diamines with Specific Configurations: cis- and Diequatorial trans-Diamino-trans-decalins, cis- and trans-Diaminotetralins and 3,3-Dimethyl-1,2-diaminobutane
Authors: Yano Tairoku , Kobayashi Hiroshi , Ueno Keihei 
Published: July 2006

Abstract
Stability constants were determined at 25 °C for the metal chelates of racemic cis- and diequatorial trans-2,3-diamino-trans-decalins, cis- and trans-2,3-diaminotetralins and 3,3-dimethyl-1,2-diaminobutane (BEDA), where Cu(II), Ni(II) and Zn(II) are metal ions. Alicyclic trans-diamines afforded 1 :1 complexes more stable than those with cis-isomers, regardless of the metal ions. Stability of the metal chelates with BEDA is comparable to that of the trans-diamines. The difference in stability of the trans- and cis-diamine complexes increased in the order Cu-, Zn- and Ni ions. Upon formation of 1 : 2 complexes, it became greater with Ni ion, but practically no difference was observed with the others. An explanation was given on the basis of stereochemistry of the diamines and coordination structures of the divalent metal ions.
Binuclear Metal Complexes. XIII. Syntheses and Magnetic Properties of Thiocyanato-Bridged Binuclear Copper(II) Complexes
Authors: Ichinose Tomoko , Nishida Yuzo , Okawa Hisashi , Kida Sigeo 
Published: July 2006

Abstract
Three binuclear copper(II) complexes, Cu2(fsal-NMe2)(NCS)3, Cu2(fsal-NEt2)(NCS)3 and Cu2(fsal-pa)(NCS)3, have been synthesized and characterized, where Hfsal-NMe2, Hfsal-ENt2 and Hfsal-pa denote the Schiff bases prepared by the condensation reaction of 2,6-diformyl-4-methylphenol with N,N-dimethylethylenediamine, N,N-diethylethylenediamine and 2-pyridylmethylamine, respectively. It was demonstrated that the complexes essentially consist of a binuclear unit of the thiocyanato-bridged skeleton, (Remark: Graphics omitted.). The cryomagnetic properties could be explained on the basis of the equation for the tetranuclear cluster formed with two binuclear units linked by the out-of-plane bonding. The magnetisms and structures of the complexes were discussed in comparison with those of the Cu2(fsal–NR2)X3 (X=Cl, Br).
Six-coordinate Copper(II) Complexes Derived from the Reactions of Bis(acetylacetonato)- and Bis(ethyl acetoacetato)-copper(II) with Some Bidentate Nitrogen Bases
Authors: Kurauchi Takeo , Matsui Masanori , Nakamura Yukio , Ooi Shun’ichiro , Kawaguchi Shinichi , Kuroya Hisao 
Published: July 2006

Abstract
Green-to-blue six-coordinate mixed complexes, Cu(acac)2(en) and Cu(etac)2(diamine)(acac=acetylacetonate anion; etac=ethyl acetoacetate anion; diamine=ethylenediamine, trimethylenediamine, 2,2′-bipyridine or 1,10-phenanthroline) have been isolated by the reactions of the respective parent β-diketonate with the corresponding diamine in dry dichloromethane. On the other hand, the reaction of Cu(acac)2 with en in the mole ratio of one-to-two in dichloromethane saturated with water has resulted in purple crystals of Cu(acac)2(en)2·2H2O. This compound has been shown by X-ray analysis to consist of a square-planar copper(II) cation, coordinated by two ethylenediamine molecules, and two planar acetylacetonate anions, the plane of which is not perpendicular to, but slanted against, the CuN4 plane. One oxygen atom of the anion participates in the N–H···O hydrogen bonding with an NH2 group of the ethylenediamine molecule, while the other occupies the axial position of Cu(en)22+ (Cu···O: 2.79(1) Å). Therefore, the compound can be designated by the formula [Cu(en)2]·(acac)2·2H2O. The water hydrogen atoms seem to take part in the hydrogen bonding with the anion oxygen atoms.
Circular Dichroism Spectra of Cobalt(III) Complexes Containing Amino-Alcohols
Authors: Nishide Toshikazu , Ogino Kazuko , Fujita Junnosuke , Saito Kazuo 
Published: July 2006

Abstract
Several cobalt(III) complexes containing amino-alcohol (amOH) chelate rings, [Co(amOH)(NH3)4]X3, [Co(amOH)(en)2]X3 and [Co(amOH)(R-chxn)2]X3 (en=ethylenediamine, chxn=trans-1,2-diaminocyclohexane, X−=Cl−, Br− or ClO4−, amOH=2-aminoethanol, 2-amino-1-propanol, 1-amino-2-propanol, etc.) were synthesized and separated into optical isomers. Their circular dichroism (CD) spectra change remarkably by the change in pH of the solution. The changes were ascribed to the dissociation of the alcoholic proton of coordinated amOH. The complexes containing a deprotonated chiral amO− chelate ring exhibit strong vicinal CD bands in the first and second absorption band region. The signs and the magnitudes of these CD bands seem to depend mainly on the conformation of the amO− chelate ring.
Abnormal Benzo Substituent Effect on Free Radical Formation Process. A Local Symmetry Effect
Authors: Tabushi Iwao , Yoshida Zen-ichi , Aoyama Yasuhiro 
Published: July 2006

Abstract
Relative stabilities of 1-bicyclo[2.2.2]octyl (9), 1-benzobicyclo[2.2.2]-octenyl (10), 1-dibenzobicyclo[2.2.2]octadienyl (11), and 1-tribenzobicyclo[2.2.2]octatrienyl(12) radicals were obtained by means of the relative rates of the free radical bromine abstraction from the corresponding bridgehead bromides by a silyl radical. It was found that 9 and 12 were more stable than expected. The observed order of stability 9&gt;10&gt;12&gt;11 can not be explained by the usual concepts alone. The extra stabilization of 9 or 12 (or destabilization of 10 or 11) was interpreted in terms of the local symmetry (or local asymmetry) of these radicals.