bluuebunny/crossref_metadata_2025_split huggingface dataset:
Convenient Syntheses of Vitamin K and Coenzyme Q by the Coupling of Grignard Reagents with Allylic Phosphate
Authors: Araki Shuki , Sato Takashi , Miyagawa Hiroyuki , Butsugan Yasuo 
Published: July 2006

Abstract
Convenient syntheses of vitamin K and coenzyme Q are described. Grignard coupling of polyprenyl diethyl phosphates with 1,4-dimethoxy-3-methyl-2-naphthylmagnesium bromide gave high yields of the polyprenylated hydroquinone dimethyl ethers regioselectively with the preservation of the stereochemistry. The precursors of coenzyme Q were similarly obtained by the coupling of 2,3,4,5-tetramethoxy-6-methylphenylmagnesium bromide and the polyprenyl phosphates. The synthesized (polyprenyl)hydroquinone dimethyl ethers are known to be oxidized to the biologically active quinones.
Preparation and Spectroscopic Studies of the Stereoisomers of [Co(acac)2(R1R2NCH2CH2NR3R4 or o-Phenylenediamine)]+ (R1–R4=H, CH3, or C6H5; acac=2,4-Pentanedionate ion) and Isomer Distribution at Equilibrium
Authors: Ouyang Yue , Kojima Masaaki , Fujita Junnosuke 
Published: July 2006

Abstract
A series of complexes of the type, [Co(acac)2L]+, where acac=2,4-pentanedionate ion and L denotes R1R2NCH2CH2NR3R4 (R1–R4=H or CH3), N-phenylethylenediamine, N,N′-diphenylethylenediamine, and o-phenylenediamine were prepared and the isomers separated. The absorption spectra and the distributions of the isomers at equilibrium were determined and the results are discussed.
Ab Initio Gradient Calculation of the Molecular Structures of Dimethyl Ether and Dimethyl Sulfide
Authors: Tsuboyama Akira , Takeshita Kouichi , Konaka Shigehiro , Kimura Masao 
Published: July 2006

Abstract
The molecular structures and torsional potentials of (CH3)2O and (CH3)2S have been calculated by the ab initio gradient method using a MIDI-4 basis set augumented with polarization functions. The calculations have confirmed that the molecules take the staggered-staggered conformation with C2v symmetry.
The Phosphorus-31 Nuclear Magnetic Resonance Spectra of Bis(acetylacetonato)cobalt(III) Complexes Containing Bidentate Diphosphines
Authors: Koike Yoshio , Takayama Toshio , Watabe Masatoshi 
Published: July 2006

Abstract
The phosphorus-31 nuclear magnetic resonance spectra of [Co(acac)2(P-P)]+(P-P=diphosphine ligand) of the Werner type were measured, and the coordination chemical shifts were compared with those of complexes studied before. The coordination chemical shifts of the five-membered chelate ring were twice as much as those of the six-membered ring.
A Facile Method for Activation of Carboxylic Acids
Authors: Murata Shizuaki 
Published: July 2006

Abstract
1,1′-Oxalyldiimidazole, -1,2,4-triazole, and -1,2,3,4-tetrazole were prepared in situ from oxalyl dichloride and corresponding 1H-azoles. The 1,1′-oxalyldiazoles converted carboxylic acids and their salts into 1-acylazoles.
Reactions of Trifluoromethanesulfonyl Azide with Aromatic Compounds
Authors: Kamigata Nobumasa , Yamamoto Kazutoshi , Kawakita Osamu , Hikita Kiyoyuki , Matsuyama Haruo , Yoshida Masato , Kobayashi Michio 
Published: July 2006

Abstract
Thermolysis of trifluoromethanesulfonyl azide in solvents composed of 1:1 mixtures of benzene and substituted benzenes gives trifluoromethanesulfonanilide and substituted trifluoromethanesulfonanilides. The isomer ratios, the total rate ratios, and the partial rate factors for the sulfonamidation have been determined. By the intramolecular and intermolecular selectivities, the reaction mechanism involving trifluoromethanesulfonyl nitrene intermediate is discussed.
A Simple Synthesis of Methyl 2,3,6- and 2,4,6-Tri-O-benzyl-α-d-mannosides
Authors: Koto Shinkiti , Takenaka Kazuhiro , Morishima Naohiko , Sugimoto Akiko , Zen Shonosuke 
Published: July 2006

Abstract
Cotrolled benzylation of methyl α-d-mannopyranoside with benzyl chloride and LiOH selectively gave the 2,3,6-tribenzyl ether in a 53% yield. Such a reaction using benzyl chloride and KOH afforded mainly the 2,4,6-tribenzyl ether in a 41% yield. The products were allylated and then hydrolyzed to give the corresponding 1-OH derivatives.
The Synthesis of Racemic Dihydroageratone. Efficient Demethylation by Magnesium Iodide Etherate
Authors: Yamaguchi Seiji , Sugiura Kyoichi , Fukuoka Reiko , Okazaki Kazumi , Takeuchi Mie , Kawase Yoshiyuki 
Published: July 2006

Abstract
2-Isopropenyl-6-methoxy-2,3-dihydrobenzofuran, prepared from m-methoxyphenol and 1,4-dibromo 2-methyl-2-butene, was converted to racemic dihydroageratone via oxidation with selenium dioxide, the acetylation with acetic acid–trifluoroacetic anhydride, and the demethylation with magnesium iodide etherate.
Potentiometric and Calorimetric Studies on the Formation of Ethylenediamine Complexes of Copper(II) Ion in Water and Aqueous Dioxane Solutions
Authors: Ishiguro Shin-ichi , Oka Yoshihiro , Ohtaki Hitoshi 
Published: July 2006

Abstract
Gibbs energies (or formation constants), enthalpies and entropies of formation of ethylenediamine complexes of copper(II) ions have been determined by means of potentiometric and calorimetric titrations at 25 °C in an aqueous solution and dioxane–water mixtures (dioxane contents are 0.1 and 0.2 mole fractions, which correspond to 35.2 and 55.0% w/w, respectively), all containing 3 mol dm−3 LiClO4 as a constant ionic medium. The thermodynamic quantities of the reactions CuLn−12++L=CuLn2+ (L=ethylenediamine and n=1 and 2) determined in the solutions were as follows: ΔG1°=−65.0 kJ mol−1 (dioxane content: 0.0 mole fraction), −66.8 kJ mol−1 (0.1 mole fraction), and −68.8 kJ mol−1 (0.2 mole fraction); ΔG2°=−56.9 kJ mol−1 (0.0), −58.8 kJ mol−1 (0.1), and −61.1 kJ mol−1 (0.2); ΔH1°=−67.7 kJ mol−1 (0.0), −68.6 kJ mol−1 (0.1), and −66.7 kJ mol−1 (0.2); ΔH2°=−71.0 kJ mol−1 (0.0), −70.2 kJ mol−1 (0.1), and −68.8 kJ mol−1 (0.2); TΔS1°=−2.7 kJ mol−1 (0.0), −1.8 kJ mol−1(0.1), and 2.1 kJ mol−1 (0.2); TΔS2°=−14.1 kJ mol−1 (0.0), −11.4 kJ mol−1(0.1), and −7.7 kJ mol−1 (0.2). In any solvent examined the enthalpies contribute predominantly to the Gibbs energies. On the other hand, for a given complex with varying solvent compositions, the entropies mainly contribute to the change in the Gibbs energies of the complex formation reactions. With an increase in the dioxane content of the solvent, the Gibbs energies of the complex formation reactions become more negative, while the enthalpies of the reactions remain practically unchanged or even become less negative. Consequently, the entropies of the reactions increase with increasing dioxane content of the solvent, which is explained in terms of weakening of the hydrogen-bonded structure of water in the bulk solvent by the addition of dioxane.
Preparation and Spectral Behavior of Polyoxadithia[n]ferrocenophanes and Their Silver(I) Nitrate Complexes
Authors: Sato Masaru , Kubo Masao , Ebine Seiji , Akabori Sadatoshi 
Published: July 2006

Abstract
Polyoxadithia[n]ferrocenophanes and polyoxatetrathia[n.n]ferrocenophanes were prepared by treatment of 1,1′-ferrocenedithiol with α,ω-dibromo polyethers. The ferrocenophanes formed efficiently a complex with a silver ion, but not with alkali and alkali-earth metal ions. The spectral data of the silver ion-complexed ferrocenophanes suggested the presence of a partial electron-transfer interaction between the iron atom and the complexed silver ion.
Mechanism of Formation of α,β-Unsaturated Esters in the Reaction of Ethyl Mercaptoacetate Dianion with Carbonyl Compounds
Authors: Matsui Syuichi 
Published: July 2006

Abstract
Dianion derived from ethyl mercaptoacetate undergoes aldol type reaction with a carbonyl compound to give an adduct, which exhibited low diastereoselectivity. However, the adducts obtained by the reaction with a variety of aldehydes were subsequently treated with ethyl chloroformate in the presence of trivalent phosphorus compound to give (E)-isomers of α,β-unsaturated esters in high yields with greater than 85% stereoselectivity regardless of the stereochemistry of the diastereomers of the adducts. The stereochemical mechanism and application of this reaction were studied in detail.
N-Hydroxy Amides. I. Synthesis of N-Benzyloxy and N-Hydroxy Peptides via Polymerization of N-Benzyloxy Dl-α-Amino Acid N-Carboxy Anhydrides
Authors: Shimizu Kazuyuki , Hasegawa Masayoshi , Akiyama Masayasu 
Published: July 2006

Abstract
Polymerization of N-benzyloxy Dl-α-amino acid N-carboxy anhydrides (N-benzyloxy-NCAs) has been carried out in benzene for 30 d with cyclohexylamine as initiator. The N-benzyloxy-NCAs of glycine, alanine, 2-aminobutyric acid, and leucine give the corresponding polymers in good yields, while the starting material is recovered from those of valine and phenylalanine. The different behavior in the polymerization is discussed in terms of steric crowding. Catalytic hydrogenation of the N-benzyloxy polymers produces poly(N-hydroxy peptide)s. Complex formation of these polymers with iron(III) has been examined. Among the polymers, poly(N-hydroxyalanine) is further converted into poly(N-acetoxyalanine), which acts as an acyl active polymer. Treatment of poly(N-benzyloxyalanine) with B(CF3CO2)3 gives 1,4-dihydroxy-3,6-dimethyl-2,5-piperazinedione.
The Carbon-13 NMR Spectra and Electronic Structure of 3H-Phenothiazin-3-one and Its Methyl Derivatives
Authors: Hasegawa Kan-ichi , Ueno Yoshio 
Published: July 2006

Abstract
The 13C NMR chemical shifts of 3H-phenothiazin-3-one (1) and eleven of its methyl derivatives are reported. The effect of including sulfur 3d orbitals is discussed in relation to the 13C chemical shifts. The chemical shifts of 1 can be explained in terms of both the successive polarization of the long π-conjugated framework promoted by the carbonyl group and the contribution of the sulfur d-orbitals. The 13C chemical shifts gave a better correlation with the CNDO/2 π- and total electron densities calculated by means of the sp-basis set than by means of the spd-basis set, but an improved correlation was obtained by reducing the extent of d-orbital participation on sulfur. From the correlation of the 13C chemical shifts with the CNDO/2 sp π- and the total electron densities of all the carbons of 1 and monomethyl derivatives, the proportionality constants of −300 and −180 ppm/e respectively were obtained.
Preparation of S,S-Diphenylsulfilimines, -sulfoximines, and -N-(p-tolylsulfonyl)sulfonediimines N-Substituted with Sulfur Groups of Different Oxidation States
Authors: Akutagawa Kunihiko , Furukawa Naomichi , Oae Shigeru 
Published: July 2006

Abstract
S,S-Diphenyl-N-(p-tolylthio)-, -N-(p-tolylsulfinyl)-, -N-(p-toluenesulfinimidoyl)-, -N-(p-tolylsulfonyl)-, and -N-(p-toluenesulfonimidoyl)sulfoximines have been synthesized either by sulfenylation, sulfinylation, sulfinimidoylation, sulfonylation, and sulfonimidoylation or by oxidation of the N-substituted sulfoximines with sulfur groups of lower oxidation states, i.e., the N-sulfenylated sulfoximine. Similar attempts have been made on similarly substituted sulfonediimines. Sulfenylation and sulfonylation of N-unsubstituted N-(p-tolylsulfonyl)sulfonediimine were unsuccessful but its sulfinylation underwent nicely. An attempt to disulfonylation of the N,N′-unsubstituted sulfonediimine ended up in the monosulfonylation. N,N′,-bis(p-Tolylsulfonyl)sulfonediimine was successfully prepared by oxidation of the N-(p-tolylsulfinyl)-N′-(p-tolylsulfonyl)sulfonediimine with m-chloroperbenzoic acid.
N-(Phenylsulfonyl)- and N-Methyl-N-(phenylsulfonyl)benzohydrazonoyl Azides. Thermally Induced Cyclization to Tetrazoles and Decomposition to Benzonitriles
Authors: Ito Suketaka , Tanaka Yumo , Kakehi Akikazu 
Published: July 2006

Abstract
N-(Phenylsulfonyl)- and N-methyl-N-(phenylsulfonyl)benzohydrazonoyl azides, prepared from the corresponding hydrazonoyl chlorides and sodium azide, undergo the cyclization to 5-phenyl-1-(phenylsulfonylamino)-1H-tetrazoles together with the competitive decomposition to benzonitriles and the Curtius-type rearrangement leading to semicarbazides when heated in benzene under reflux. The tetrazole formation of hydrazonoyl azides may be characteristic of such hydrazonoyl azides as those carrying an N-sulfonyl substituent, the strong electron-withdrawing nature of which probably promotes the cyclization.
Reactions of 2,3,5-Tri-O-benzoyl-d-ribofuranosyl Acetate with Enol Silyl Ethers Catalyzed by Tin(IV) Chloride. Regiochemical Features
Authors: Yokoyama Yayoi S , Inoue Tan , Kuwajima Isao 
Published: July 2006

Abstract
In condensation reactions of 2,3,5-tri-O-benzoyl-d-ribofuranosyl acetate with various kinds of enol silyl ethers in the presence of tin(IV) chloride, the acetate behaves as an ambident electrophile to give two types of products arising from nucleophilic attack of the enol ether on C-1 carbon of the ribose derivative and on carbonyl carbon of 2-benzoyloxyl group, depending remarkably on the enol silyl ethers.
Studies on Salt Hydrates for Latent Heat Storage. V. Preheating Effect on Crystallization of Sodium Acetate Trihydrate from Aqueous Solution with a Small Amount of Sodium Pyrophosphate Decahydrate
Authors: Wada Takahiro , Matsunaga Koji , Matsuo Yoshihiro 
Published: July 2006

Abstract
Influences of preheating temperature and time were studied on the crystallization of CH3CO2Na·3H2O from three kinds of CH3CO2Na aqueous solutions, whose concentrations were 58.0, 60.3, and 62.8 wt% and which contained a small amount of crystal nucleation catalyst, Na4P2O7·10H2O. In 60.3 wt% aqueous solution (CH3CO2Na·3H2O), the nucleation catalyst begins to get deactivated by preheating at about 81 °C, higher by 23 °C than the melting point of CH3CO2Na·3H2O. The temperature at which the catalyst begins to get deactivated is raised with increasing CH3CO2Na concentration of the solution; thus, in 62.8 wt% CH3CO2Na aqueous solution, the catalyst begins to get deactivated at 85 °C. One hundred samples, each consisting of 8 g of 60.3 wt% CH3CO2Na aqueous solution and 0.16 g of Na4P2O7·10H2O, all crystallized on cooling to 40 °C, even after they had been preheated at 80 °C for 39 h. These results are explained on the basis of the crystalline adsorption model proposed by Richards.
Studies on Salt Hydrates for Latent Heat Storge. VI. Preheating Effect on Crystallization of Sodium Acetate Trihydrate from Aqueous Solution with a Small Amount of Disodium Hydrogenphosphate
Authors: Wada Takahiro , Matsuo Yoshihiro 
Published: July 2006

Abstract
With particular reference to the use of Na2HPO4 as nucleation catalyst for crystallization of CH3CO2Na·3H2O, influences of preheating temperature and time were studied on the crystallization of CH3CO2Na·3H2O from three kinds of CH3CO2Na aqueous solutions, whose concentrations were 58.0, 60.3, and 62.8 wt%. In 60.3 wt% aqueous solution (CH3CO2Na·3H2O), the nucleation catalyst begins to get deactivated by preheating at 81 °C. The temperature at which the catalyst begins to get deactivated is slightly raised with increasing CH3CO2Na concentration of the solution. The results obtained are compared with those previously reported on the use of Na4P2O7·10H2O as nucleation catalyst, and are discussed on the basis of the crystalline adsorption model.
Kinetic Studies of the Polyiodide Complex Formation in the Iodine–Iodide Solutions
Authors: Sano Takayuki , Hori Hiroka , Yamamoto Masako , Yasunaga Tatsuya 
Published: July 2006

Abstract
A relaxation obviously different from that due to the triiodide complex formation was observed by the temperature-jump experiments in the iodine–iodide solution. On the basis of the dependences of the relaxation time on the concentration of iodine and iodide and on the temperature, the relaxation was assigned to the complex formation of I62−. The rate constants of the reaction were estimated to be 2.2×105 M−1 s−1 and 5.3×105 s−1 for forward and backward processes, respectively.
Determination of the Vapor Pressures of Cesium Fluoride and Cesium Chloride by Means of Surface Ionization
Authors: Kawano Hiroyuki , Kenp\={o} Tsutomu , Hidaka Yoshiaki 
Published: July 2006

Abstract
A molecular beam of CsF or CsCl effusing from a Knudsen cell was detected with a heated rhenium filament, and the vapor pressure P (in atm) of each halide at a temperature T (in K) was found to be expressed by log10P(CsF)=(7.239±0.072)–(9883±72)⁄T for 630–830 K, log10P(CsCl)=(7.269±0.064)–(10054±66)⁄T for 640–820 K.
The Reaction of 3,5-Diphenyl-1,2,4-dithiazol-1-ium Perchlorate with Active Methylene Compounds
Authors: Shibuya Isao 
Published: July 2006

Abstract
The reaction of 3,5-diphenyl-1,2,4-dithiazol-1-ium perchlorate with several kinds of active methylenes gives a number of heterocycles, such as 4-hydroxy and 4-mercaptopyrimidine, pyrimidinone, and thiazole derivatives. On treatment with hydroxylamine-O-sulfonic acid, the 4-mercaptopyrimidines lead to the aminothio compounds or the isothiazolo[5,4-d]pyrimidine.
Acylations of 2-Isopropenyl-2,3-dihydrobenzofurans
Authors: Yamaguchi Seiji , Miyata Aiko , Ueno Mariko , Hase Takayuki , Yamamoto Kenichi , Kawase Yoshiyuki 
Published: July 2006

Abstract
Methoxy-substituted 2-isopropenyl-2,3-dihydrobenzofurans were prepared from methoxy-substituted phenols and 1,4-dibromo-2-methyl-2-butene in one-step reactions. Their acylations with acetic acid–trifluoroacetic anhydride or N-methylformanilide–phosphoryl chloride were studied.
Plastic Phase of Formylferrocene Studied by X-Ray Diffraction and Mössbauer Spectroscopy
Authors: Sato Kumiko , Iwai Makoto , Sano Hirotoshi , Konno Michiko 
Published: July 2006

Abstract
The structures of both the crystal and the plastic phases of formylferrocene have been determined to be orthorhombic by single-crystal X-ray diffraction. The structural change proposes a mechanism of the transition that postulates the translational molecular motion along the a-axis. Mössbauer spectra observed in the plastic phase show little fluctuation of the electric field gradient ascribed to the orientational disorder between x, y, and z axes of the molecule.
Crystal Structure and NMR Spectral Studies of Alkali Thiocyanate Complexes with Polyoxa[n]ferrocenophanes
Authors: Akabori Sadatoshi , Habata Yoichi , Sato Masaru 
Published: July 2006

Abstract
1H- and 13C-NMR spectra of free ligands and their alkali metal complexes with a new type of crown ethers containing a ferrocene unit have been recorded. The change of chemical shifts in 1H- and 13C-NMR spectra was attributed to an electronic field effect and a conformational change on the metal complexation, respectively. The crystal structure of the complex of 1,4,7,10,13-pentaoxa[13]ferrocenophane with sodium thiocyanate was determined by the X-ray method. The crystals are orthorhombic, space group Cccn, with a=20.579(4), b=25.622(8) c=7.606(1) Å, U=4010(2) Å3, Z=8, Dc=1.48 g cm−3. The distances between the iron atom of a ferrocene nucleus and the incorporated sodium cation and between the sodium cation and the nitrogen atom of a counter anion are 4.129 and 2.541 Å, respectively. The results suggest that the iron atom of the ferrocene does not take part directly in complex formation and that the sodium cation forms a contact ion pair with the nitrogen atom of a counter anion.
The Sodium Isotopic Exchange Rate between High-temperature Phases of Disodium Zirconium(IV) Bis(orthophosphate) and Aqueous Solutions
Authors: Inoue Yasushi , Yamada Yoshimune 
Published: July 2006

Abstract
A monohydrate (Phase II) and three anhydrous phases prepared by the thermal treatment (at 250, 700, and 900 °C respectively for Phases III, IV, and V) of disodium zirconium(IV) bis(orthophosphate) trihydrate were studied from the sodium isotopic exchange rate between them and aqueous solutions. In Phases III and IV, which had been sufficiently adapted in water in advance, the rate was found to be controlled by the diffusion of sodium ions along the direction perpendicular to the layers consisting of zirconium atoms and the diffusion constants, and their activation energies (for Phases III and IV, 57 and 52 kJ/mol) were evaluated. When these phases were used as dried, the rate was governed by the irreversible dissociation of sodium in the solid phases. In Phase II, used as dried, and in Phase V, used as dried and wetted, the rate was controlled by neither particle diffusion, film diffusion, nor chemical reaction alone. This behavior was attributed to the complex behavior of phase transformation as the isotopic exchange proceeded.
Stability Constants of Scandium Complexes. I. Monocarboxylate Complexes Species
Authors: Itoh Hisako , Itoh Naomi , Suzuki Yasuo 
Published: July 2006

Abstract
The stability constants of scandium complexes with some carboxylate ligands were determined potentiometrically at 25.0 and 40.0 °C and at an ionic strength of 0.10 with potassium nitrate as supporting electrolyte. The constants of the scandium complexes were appreciably greater than those of the corresponding lanthanoid complexes, as expected. The changes in free energy, enthalpy, and entropy for the formation of the scandium complexes were calculated from the stability constants at two temperatures.
Asymmetric Hydrogenation with Rhodium(I)–Chiral Diphosphinites. The Effect of the Dimethylamino Group of the Ligand on the Asymmetric Induction
Authors: Yatagai Masanobu , Zama Masanobu , Yamagishi Takamichi , Hida Mitsuhiko 
Published: July 2006

Abstract
New chiral diphosphinites were prepared starting from (+)-diethyl tartrate. The asymmetric hydrogenation of dehydroamino acids, itaconic acid and dehydrodipeptides was studied using Rh(I)-diphosphinite catalysts. In the hydrogenation of dehydroamino acid derivatives, an introducion of ω-(dimethylamino)alkyl group in the ligands did not raise the optical yield. By the use of Rh(I)-diphosphinite having 3-(dimethylamino)propyl group, the inversion of the preferred product was observed. Itaconic acid can be hydrogenated in a good optical yield (76% e.e.) by use of the diphosphinite having 2-(dimethylamino)ethyl group. The diphosphinites having ω-dimethylamino group gave high optical yields in the case of dehydrodipeptides with a chiral center. Especially Rh(I)-catalysts coordinated by diphosphinites with 4-methyl or 4-methoxyl group on the phenyl ring of the ligand gave excellent stereoselectivities (more than 98% d.e.) in the case of Ac–ΔPhe–(S)-Phe–OH. The effect of these new chiral diphosphinites on the asymmetric hydrogenation of dehydroamino acids, itaconic acid and dehydrodipeptides was discussed in terms of the stereocontrol induced by electrostatic interaction between the dimethylamino group of the ligand and the substrate and by the steric interaction between the ligand and the substrate.
Initial Process of Photo-oxidation of Ethanol by Uranyl Ions in the Rigid Matrix at 77 K
Authors: Harazono Toshie , Sato Shin , Fukutomi Hiroshi 
Published: July 2006

Abstract
ESR spectra of radicals produced in the uranyl ion-photosensitized decomposition of ethanol have been measured in the rigid matrix at 77 K. At high concentrations of uranyl ions (&gt;1 mol dm−3), methyl radicals were observed. With decreasing concentrations of uranyl ions, CH3\dotCHOH radicals became important, as expected from the previous studies. This result suggests that the charge transfer mechanism is important in the ethanol rigid matrix, although the hydrogen atom abstraction mechanism is accepted as the main initial process.
Conformational Studies of Neopentyl- and Trimethylsilylmethyl-substituted Germyl Radicals by Electron Spin Resonance
Authors: Mochida Kunio 
Published: July 2006

Abstract
Conformational analyses of a series of neopentyl- and trimethylsilylmethyl-substituted germyl radicals by electron spin resonance (ESR) were investigated on the basis of the modified cos2θ rule. Dimethylneopentylgermyl radical has the conformations with the neopentyl group rotating freely. On the other hand, dimethyl(trimethylsilylmethyl)germyl radical has the preferred conformations with trimethylsilylmethyl group eclipsing with the singly occupied orbital on a germanium atom. The ESR spectra of dineopentylmethylgermyl and bis(trimethylsilylmethyl)methylgermyl radicals showed the existence of two kinds of methylene protons due to the nonplanar geometries and the slow inversion of these germyl radicals. Conformations of trineopentylgermyl and tris(trimethylsilylmethyl)germyl radicals are also discussed.