bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of Diphenyl(tricyclohexylphosphine)manganese(II) and Its Reactions with Carbon Dioxide and Organic Carbonyl Compounds
Authors: Maruyama Kazunori , Ito Takashi , Yamamoto Akio 
Published: July 2006

Abstract
Treatment of Mn(acac)3 (acac=acetylacetonato ligand) with AlPh3·Et2O in the presence of PCy3 (Cy=cyclo-C6H11) gave a new diphenylmanganese(II) complex, Ph2MnPCy3 (1). Complex 1 reacted with allylic compounds, CH2=CHCH2X (X=Br, OPh, OCH2CH=CH2, and OCOCH3), to give allylbenzene. Carbon dioxide was found to be inserted into the phenyl-manganese σ-bond of 1 to give bis(benzoato)manganese complex, (PhCOO)2MnPCy3, 2, which on successive treatment with HCl and diazomethane produced methyl benzoate. Complex 1 reacted with aldehydes, ketones, and esters having no active α-hydrogen atom to give alkoxomanganese species in solution, indicating that the insertion of C=O double bond into the phenyl-manganese σ-bond occurred. On the other hand, acetone and acetophenone reacted with Ph2MnPCy3 to give benzene and 2-oxoalkyl complexes, (RCOCH2)2Mn(PCy3)m (R=Me, Ph), 3. Reaction of alcohols with 1 afforded alkoxomanganese compounds which catalyze the Tishchenko type and Meerwein-Pondorf type reactions as well as transesterification reactions at room temperature.
Functionalization of trans-Decalin. II. A Synthesis of dl-Isopetasol from trans-5-Oxodecalin-8a,2-carbolactone
Authors: Torii Sigeru , Inokuchi Tsutomu , Kawai Kiyoto 
Published: July 2006

Abstract
A stereocontrollcd synthesis of dl-isopetasol (1a) from trans-5-oxodecalin-8a,2-carbolactone (2a) is described. The key intermediate, trans-5,5-ethylenedioxy-1β,8aβ-dimethyldecalin-2-one (7b) was prepared by reductive methylation of trans-5,5-ethylenedioxydecahydrocyclopropa[d]naphthalen-2-one (5) for introducing the vicinal two methyl groups at C-1 and C-8a carbon atoms. The cyclopropyl ketone 5 was obtained by reduction of the acetal of 2a followed by (1) tosylation of the primary alcohol, (2) oxidation of the secondary alcohol with Corey’s NCS–DMS reagent, and (3) cyclization with t-BuOK. Reduction of 5 with lithium in liquid ammonia provides initially the corresponding enolate anion, which can be trapped with methyl iodide to give trans-5,5-ethylenedioxy-1α,8aβ-dimethyldecalin-2-one (7a), smoothly. Epimerization of 7a with MeONa in MeOH gave the desired intermediate 7b. Reduction of 7b with lithium in liquid ammonia gives the 2α-alcohol 8b, stereoselectively. The conversion of 8b into 1a was carried out as follows: (1) deacetalization of 8b followed with acetylation, giving trans-6α-acetoxy-4aβ,5β-dimethyldecalin-1-one (9b); (2) reduction of 9b with NaBH4 and subsequent dehydration affording the olefinic acetate 11; (3) oxidation of 11 with CrO3–pyridine complex, giving the enone 12; (4) aldol condensation of 12 with acetone followed by dehydration, isomerization of double bond, and hydrolysis, providing the desired 1a.
Stereochemistry of Elimination Reactions of Halohydrin Derivatives and Related Compounds with Butyllithium
Authors: Sugita Toshio , Nakagawa Junichi , Nishimoto Kazuhito , Kasai Yasuhiro , Ichikawa Katsuhiko 
Published: July 2006

Abstract
The erythro and threo isomers of 1-bromo-2-methoxy-1,2-diphenylethane (1), 1-bromo-2-acetoxy-1,2-diphenylethane (2), 1-bromo-2-methylsulfonyloxy-1,2-diphenylethane (3), 1-bromo-2-methylthio-1,2-diphenylethane (4), stilbene dibromide (6), and stilbene dichloride have been prepared. These compounds were allowed to react with butyllithium in various solvents to give cis- and trans-stilbenes. Depending on the solvent, the stereochemistry of the elimination of 1 changed from a complete syn-type (in nonpolar solvents) to a less-selective type. The same tendency was observed in the cases of 2 and 3. In contrast, anti-elimination was favored for 4 and 6, and a different type of solvent effect was observed. Elimination reactions with lithium metal and pentylmagnesium bromide were also carried out. Possible mechanisms for eliminations are discussed.
Molecular Dynamics in Lyotropic Mesophases Studied by 23Na NMR and ESR
Authors: Kanazawa Yoko , Kamei Hirotake 
Published: July 2006

Abstract
The hexagonal phases of sodium octadecanoate–water system NaS and sodium hexadecanoate–sodium tetradecanoate–water system Na(P+M) were studied by sodium-23 NMR and spin label ESR in the temperature range 40–100 °C, covering the transition temperature of isotropic-liquid crystal TI-L and that of liquid crystal-gel TL-G. The ESR spectrum of liquid crystal systems aligned by the magnetic field and the center line of 23Na NMR spectrum were analyzed. The motions of the alkyl chain and sodium ion are reflected on the ESR and NMR spectral shape and width. The NMR line width is predominantly determined by the local motion of the cation attached on the hydrocarbon rod. During the phase separation region its correlation time τc\simeq10−10 s is constant, comparable to that of chain motion. The change in the local motions of these two species is similar, being continuous across TI-L but drastic across TL-G.
Electrochemical Behavior of the Oxygen Radical. IV. The Reaction Mechanism of the Electrogenerated Hyperoxide Ion with Bis(acetylacetonato)cobalt(II) in Dimethyl Sulfoxide and Acetone
Authors: Kudo Setsuko , Iwase Akio 
Published: July 2006

Abstract
The reaction mechanism of the electrogenerated hyperoxide ion with bis(acetylacetonato)cobalt(II) in dimethyl sulfoxide and acetone has been investigated. The reaction was conducted in a 0.05 mol dm−3 TBAP solution at 20 °C in an open system. Co(acac)2 reacted with the hyperoxide ion which was generated by the controlled potential electrolysis of dissolved oxygen to afford the following product, [(acac)2 Co–O2–Co(acac)2]2−. The complex was separated in solution by column chromatography using alumina as the adsorbent. The electronic spectrum and oxidation state are discussed.
Gas-Chromatographic Studies of the Thermal Decomposition of Nitropentaammine-, Dinitrotetraammine-, Trinitrotriammine-, Tetranitrodiammine-, and Pentanitroamminecobalt(III) Complexes in the Solid State
Authors: Onodera Sukeo 
Published: July 2006

Abstract
The gas-chromatographic study of the thermal decompositions of the complexes, [Co(NO2)(NH3)5]Cl2 (I), cis- (II) and trans-[Co(NO2)2(NH3)4]Cl (III), [Co(NO2)3(NH3)3] (IV), K[Co(NO2)4(NH3)2] (V), and K2[Co(NO2)5NH3] (VI) are reported. The EGA curves for these complexes show that the compounds decompose in two or three stages. In the first stage (ca. 140–240 °C), all complexes evolve nitrogen with the evolution of ammonia and/or nitrogen monoxide. The second stage (ca. 210–300 °C) has been ascribed to the evolution of ammonia from the intermediate dissociation products of compound I, II, and III. The third stage (ca. 275–350 °C) has been ascribed to the evolution of nitrogen monoxide from the solid residue with the exception of IV.
The X-Ray Structure of Bis((S,S)-2,4-pentanediamine)platinum(II) Ion, [Pt(SS-ptn)2]2+
Authors: Nakayama Yasuji , Ooi Shun’ichiro , Kuroya Hisao 
Published: July 2006

Abstract
The bis((S,S)-2,4-pentanediamine)platinum(II) chloride monohydrate crystallizes in the space group P212121 with four formula units in a unit cell of dimensions a=12.089(3), b=13.547(3), c=10.697(2) Å. The crystal structure has been determined from diffractometer data and refined to R=0.052 for 1903 independent reflections. The Pt atom has a square planar coordination by four N atoms, the average value of the Pt-N distance being 2.05 Å. The complex has a pseudo two-fold axis which is perpendicular to the coordination plane defined by the four N atoms. The 6-membered chelate ring is of a chair conformation and one methyl group is axial with respect to the chelate ring, while the other is equatorial. From a comparison of the circular dichroism spectra of the diammine-(S,S)-2,4-pentanediamineplatinum(II) and the bis((S,S)-2,4-pentanediamine)platinum(II) ions, the effect of the (S,S)-2,4-pentanediamine on the rotatory strength of the Pt(II) complex has been found to be not additive.
Fluorescence from Bound Ionic States of Neat Molecular Crystals: p-Substituted N,N-Dimethylanilines
Authors: Araya Kotaro , Aihara Jun-ichi 
Published: July 2006

Abstract
Fluorescences were detected from bound ionic states (i.e., charge-transfer exciton states) of two neat molecular crystals, each formed by a single molecular component. These fluorescent compounds are p-(2,2-dicyanovinyl)-N,N-dimethylaniline and p-(2-nitrovinyl)-N,N-dimethylaniline. They are dimorphic in the solid state.
Mechanism of the Ferroelectric Phase Transition in K4[Fe(CN)6]·3H2O and K4[Fe(CN)6]·3D2O
Authors: Oguni Masaharu , Matsuo Takasuke , Suga Hiroshi , Seki Syûzô 
Published: July 2006

Abstract
Mechanism of the ferroelectric phase transition in potassium hexacyanoferrate trihydrate is discussed from static and dynamic points of view, and a new model is proposed. The model takes into account four states as accessible for a water trimer, instead of two in the earlier model. If the four states were equally probable in the disordered phase, the predicted transition entropy is R In 4 compatible with the experimental value. It is expected that a glass transition, if possible, occurs at 50–60 K for the model. Since the anomalous heat capacity in this temperature region is effectively zero, the model is consistent with absence of a glass transition. Occupancy fractions of hydrogen sites are given for the earlier and the present models.
Super High Sensitivity of CuSe–Ag2S Solid Membrane Copper(II) Ion Selective Electrode in Several Metal Buffer Solutions
Authors: Umezawa Yoshio , Imanishi Yuichiro , Sawatari Katsuhiko , Fujiwara Shizuo 
Published: July 2006

Abstract
A CuSe–Ag2S solid membrane Cu(II) ion electrode in certain metal buffer solutions gave detection limit of free Cu(II) ion as low as 10−18M.
Reaction of Optically Active 1-Dimethylaminoethylferrocene Palladium Complexes
Authors: Kasahara Akira , Izumi Taeko , Watabe Hiroyuki 
Published: July 2006

Abstract
ortho-Palladation products of optically active 1-dimethylaminoethylferrocene were treated with phenyl vinyl ketone and carbon monoxide and a variety of optically active 1,2-disubstituted ferrocene derivatives were obtained.
Nature of Bonding in Pyrazine-2,3-dicarboxamide Complexes of Copper(II), Cobalt(II), and Nickel(II)
Authors: Sanyal G S , Mondal S K 
Published: July 2006

Abstract
Pyrazine-2,3-dicarboxamide complexes with the perchlorates of copper(II), cobalt(II), and nickel(II) have been prepared and characterised, copper having a square planar configuration and cobalt and nickel an octahedral geometry. Bonding takes place through a ring nitrogen and the oxygen atom of the adjacent amide group.
Studies on the Aqueous Solutions of Guanidinium Salts. IX. Activity Coefficients of Biguanide Hydrochloride and Sucrose in Aqueous Ternary Solutions at 25 °C
Authors: Miyajima Koichiro , Nakanishi Shigeo , Nakagaki Masayuki 
Published: July 2006

Abstract
Activity coefficients for the ternary system biguanide·HCl–sucrose–water were determined by the isopiestic vapor pressure method at 25 °C. Biguanide hydrochloride (Bg·HCl) and sucrose each decreased the activity coefficient of the other solute, showing a mutual salting-in effect. The excess free energy of mixing was negative and its magnitude was about twice as large as that of the system urea–sucrose–water. The pair interaction parameter {Bg·HCl–sucrose}g was calculated to be −89.2 (cal mol−2 kg). Thermodynamic properties of this system were found to be similar to those of the system urea–sucrose–water, indicating that Bg·HCl exerted a structure breaking effect on the aqueous solutions of sucrose as urea did.
Energy Levels and g Values of Some Rare Earth Crystals with f2 Configuration
Authors: Kato Yoshifumi , Takada Hirokazu 
Published: July 2006

Abstract
The energy levels of the rare earth ions in praseodymium ethyl sulfate, magnesium praseodymium nitrate, and thulium ethyl sulfate crystals are calculated by using an extended Hamiltonian for 4f2 configuration. The Hamiltonian includes two-body electrostatic interactions, spin-other-orbit interactions and two-body pseudomagnetic interactions as configuration-mixing parameters in addition to the Slater, spin-orbit coupling and crystal-field parameters. The standard deviations for praseodymium ethyl sulfate, magnesium praseodymium nitrate and thulium ethyl sulfate are respectively 10.1 cm−1 for 25 observed levels by using 13 parameters, 3.8 cm−1 for 12 observed levels by using 11 parameters, and 8.9 cm−1 for 32 observed levels by using 13 parameters. These results are consistent with similar studies of rare earth ions doped in the LaCl3 and LaF3 crystals. Most of the calculated Zeeman splitting factors (g value) parallel to the principal axis of the crystals also are in fairly good agreement with the experimental values. Some discussion is given as to the effect of configuration interactions, the accuracy of wave functions obtained and the discrepancy between some of the calculated g values and the observed ones.
Magnetic Circular Dichroism of Praseodymium Ethyl Sulfate and Praseodymium–Magnesium Double Nitrate
Authors: Kato Yoshifumi , Asano Motoshi 
Published: July 2006

Abstract
The magnetic circular dichroism of praseodymium ethyl sulfate and praseodymium–magnesium double nitrate was measured in the visible wave number region at low temperatures down to 17 K. Analysis was carried out for six absorption bands of praseodymium ethyl sulfate and three bands of praseodymium–magnesium double nitrate. With available information on energy levels., the g values of the crystal-field levels relevant to absorptions were derived from the MCD parameters obtained. These values are in good agreement with those from other methods.
Layered Compounds. LXI. Carbon-13 NMR Study of [n]-, [n.n]-, and Multilayered [2.2]Paracyclophanes
Authors: Kaneda Takahiro , Otsubo Tetsuo , Horita Hisanori , Misumi Soichi 
Published: July 2006

Abstract
The carbon resonances of several [n]paracyclophanes (n=8–12) were assigned with the aid of partially deuterated derivatives. The 13C NMR spectra of the title paracyclophanes were examined from viewpoints of the steric compression effect and the ring-current effect. Although the compression effect is a dominant factor for carbon resonances of closely stacked paracyclophanes, the ring-current effect was evidently observed in the spectra of [10]paracyclophane–[10](9,10)anthracenophanepair, [3.3]paracyclophane, and multilayered [2.2]paracyclophanes.
Thione S-Imides. The Reaction with Carbon-Hetero Atom Double Bond
Authors: Saito Takao , Oikawa Isao , Motoki Shinichi 
Published: July 2006

Abstract
9-Fluorenethione S-p-toluenesulfonimide reacted as a 1,3-dipole with imines, oximes, and thiones to form (3+2)cycloadducts, while with symmetrical azines and aldehydes, unsymmetrical azines, N-(p-tolylsulfonyl) imines and fluorenone were obtained as a result of the decomposition of the cycloadducts.
Substituent Effects in Heterogeneous Catalysis. VI. Competitive Hydrogenation of Methylenecyclohexane and 2-Methyl-methylenecyclohexane over Platinum Group Metals
Authors: Taya Kazuo , Morimoto Shinya , Abe Chieko , Nomura Kazumi , Nomura Okio , Tanaka Kazunori 
Published: July 2006

Abstract
Methylenecyclohexane and its 2-methyl derivative were hydrogenated competitively in cyclohexane at 30 °C over platinum group metals. The methyl derivative was less reactive than the unsubstituted olefin on all the metal catalysts used. The reactivity of the methyl derivative relative to the unsubstituted olefin was not much different in going from one catalyst to another. However, Pd was unique in its very high activity for double bond migration. MINDO/2 calculations have revealed that the olefinic double bonds of the substituted and unsubstituted olefins are essentially identical in bond order but somewhat different in charge density. The observed methyl substituent effect is compared with that observed previously in hydrogenation of cyclohexanone and its 2-methyl derivative.
The Reaction of 2-(Trialkylsiloxy)furans with Lead(IV) Acetate. The Synthesis of dl-Pyrenophorin
Authors: Asaoka Morio , Yanagida Noboru , Sugimura Naoyuki , Takei Hisashi 
Published: July 2006

Abstract
The reaction of 2-(trimethylsiloxy)furans with lead(IV) acetate afforded the corresponding α,β-unsaturated γ-acetoxy-γ-lactones in good yields. The lactones were easily converted into the corresponding 3-acylacrylic acids. Utilizing this reaction, dl-pyrenophorin was synthesized.
Synthesis of Linear Pyranocoumarins: Xanthoxyletin, 4-Methyl-xanthyletin, and 4-Phenylxanthyletin
Authors: Ahluwalia Vindo Kumar , Bhat Krishna , Prakash Chandra , Bala Shashi 
Published: July 2006

Abstract
A convenient synthesis of linear pyranocoumarins (2H,8H-benzo[1,2-b: 5,4-b′]dipyran-2-ones), viz., xanthoxyletin, 4-methylxanthyletin and 4-phenylxanthyletin is described which uses blocking the 8-position of appropriate 7-hydroxycoumarin derivatives with iodine and 1,1-dimethyl-2-propynylation followed by cyclisation.
Fluorination with Xenon Difluoride. XXII. The Role of Catalyst and Temperature on the Fluorination of Norbornene and Norbornadiene
Authors: Gregorcic Ana , Zupan Marko 
Published: July 2006

Abstract
The reaction of norbornene was used as a mechanistic probe to elucidate the effect of catalyst (HF, HF–pyridine, BF3, BF3–etherate, and pentafluorothiophenol) and temperature (from −61 °C to 25 °C) on liquid phase fluorinatioh with xenon difluoride, resulting in the formation of seven products, depending on the reaction conditions : fluoronortricyclane, 2-endo-5-exo-difluoronorbornane, 2-exo-7-anti-difluoronorbornane, 2-endo-5-exo-difluoronorbornane, 2-exo-5-exo-difluoronorbornane, 2-exo-3-exo-difluoronorbornane, and 2-exo-7-syn-difluoronorbornane. The catalyst has a significant effect on the reaction pathways, boron trifluoride etherate favouring the formation of 2-endo-5-exo- and 2-exo-5-exo-difluoronorbornane, while pentafluorothiophenol favoured the formation of fluoronortricyclane. The catalyst and temperature has much less effect on the reaction pathways in the case of norbornadiene, four products being formed: fluoronortricyclane, 3-endo-5-exo-difluoronortricyclane, 3-exo-5-exo-difluoronortricyclane, and 2-exo-7-syn-difluoro-5-norhornene. Pentafluorothiophenol as a catalyst, when used in a greater amount, favours the formation of fluoronortricyclane.
The Benzannelated Annulenes. Dibenzo[d,j]-6,8-bisdehydrothia[13]-, [15]-, and Dibenzo[f,l]-8,10-bisdehydrothia[17]annulene
Authors: Ojima J\={u}ro , Kusaki Kiyomi , Wada Kazuyo , Nakagawa Yukiko 
Published: July 2006

Abstract
The title compounds have been synthesized by the double Wittig reaction of bis[(triphenylphosphonio)methyl] sulfide dibromide with o-ethynylbenzaldehyde and/or o-ethynylcinnamaldehyde, followed by the oxidative coupling. The 1H-NMR spectra of these compounds gave no evidence for a ring current.
Asymmetric Synthesis Catalyzed by Chiral Ferrocenylphosphine–Transition Metal Complexes. I. Preparation of Chiral Ferrocenylphosphines
Authors: Hayashi Tamio , Mise Takaya , Fukushima Motoo , Kagotani Masahiro , Nagashima Nobuo , Hamada Yuji , Matsumoto Akira , Kawakami Sota , Konishi Mitsuo , Yamamoto Keiji , Kumada Makoto 
Published: July 2006

Abstract
As chiral ligands for transition metal complex catalyzed asymmetric reactions, various kinds of chiral ferrocenylphosphines, which have planar chirality due to 1,2-unsymmetrically substituted ferrocene structure and also have a functional group on the side chain of the ferrocene nucleus, were prepared. (S)-N,N-dimethyl-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethylamine [(S)-(R)-PPFA], (S)-N,N-dimethyl-1-[(R)-1′,2-bis(diphenylphosphino)ferrocenyl]ethylamine [(S)-(R)-BPPFA], and their dimethylphosphino derivatives were prepared by way of lithiation of optically resolved N,N-dimethyl-1-ferrocenylethylamine. The 1-(dimethylamino)ethyl group on the ferrocenylphosphines was converted stereospecifically by nucleophilic substitution reactions into 1-methoxy-, 1-hydroxy-, 1-diphenylphosphino-, and several 1-(dialkylamino)ethyl groups. 1-Diphenylphosphino-2-(dimethylaminomethyl)ferrocene (FcPN) was optically resolved via its phosphine sulfide dibenzoyltartaric acid salt. The relationship between CD spectra of the chrial ferrocenylphosphines and the configuration of their planar chirality is discussed.
Spin-trapping Reactions in γ-Irradiated Benzene Solutions. Generation of Authentic Spin-adduct Radicals
Authors: Ichikawa Tsuneki , Yoshida Hiroshi 
Published: July 2006

Abstract
Spin-trapping in γ-irradiated solutions of chlorinated hydrocarbons in benzene by using 2,4,6-tri-t-butylnitrosobenzene revealed that transient free radicals are generated almost exclusively by the dissociative electron attachment to the solutes. This provides a simple, useful method for preparing the authentic spin-adducts of hydrocarbon radicals.
Photoelectron Angular Distribution Measurements for Some Aliphatic Alcohols, Amines, and Halides
Authors: Utsunomiya Chikatoshi , Kobayashi Tsunetoshi , Nagakura Saburo 
Published: July 2006

Abstract
The angular distributions for the He I photoelectron spectra of some aliphatic alcohols, amines, and halides were measured in order to reexamine the assignments of the so-called p-type photoelectron spectral bands in the He I region of these molecules. The second band of methanol and the third band of ethanol were assigned to the in-plane n orbitals localized mainly on the oxygen atom. Furthermore, it was found that the angular distributions of photoelectrons were useful for the conformational analysis of molecules and that the sum of β values was conserved for these compounds.
Kinetic Studies of the Electron Transfer Reactions in Iron(II) and Iron(III) Systems. IX. Electron Transfer Reactions between Iron(II) and Iron(III) in Water Mixed with Ethanol, 1-Propanol, Ethylene Glycol, Glycerol, and Pentaerythritol
Authors: Wada Goro , Ohta Youko , Hayashida Sachiko , Sugino Harumi , Mizui Toyomi , Aihara Yumiko 
Published: July 2006

Abstract
The rate constants of the electron transfer reactions between Fe(II) and Fe(III) were determined in mixed solvents of water and alcohols, such as ethanol, 1-propanol, ethylene glycol, glycerol, and pentaerythritol. From the acid concentration dependence of the rate, the predominant path of the reaction was estimated to be Fe2+-Fe(OH)2+ path with a rate constant kH. The rate constant kH increases with increase in the mole fraction x of ethanol and 1-propanol, and decreases with increase in x of methanol, ethylene glycol, glycerol, and pentaerythritol. A straight line is obtained when In kH is plotted against the reciprocal dielectric constant D−1 of the mixed solvents for the latter group of alcohols. From the slope of the straight line the distance between Fe2+ and Fe(OH)2+ is estimated to be 7.8 Å at the intermediate stage of the reaction. Therefore, the reaction is mostly controlled by the electrostatic repulsive force, being influenced by D of the mixed solvents.
Crystal and Molecular Structure of (Ethyl methacrylate)bis(triphenylphosphine)nickel(0)
Authors: Komiya Sanshiro , Ishizu Junichi , Yamamoto Akio , Yamamoto Takakazu , Takenaka Akio , Sasada Yoshio 
Published: July 2006

Abstract
The crystal and molecular structure of (ethyl methacrylate)bis(triphenylphosphine)nickel, (CH2=C(CH3)–COOC2H5) (PPh3)2Ni, has been determined by single-crystal X-ray analysis. The crystals are monoclinic, space group P21/c, with unit-cell dimensions a=13.690(2), b=16.855(2), c=15.699(1)Å, β=105.09(1)°, and Z=4. The structure was solved by the heavy-atom method and refined by block-diagonal least-squares technique, using 4701 independent reflections, the final R value being 0.084 for |Fo|≥3σ(F). The two phosphine ligands and the two olefinic carbon atoms comprise a distorted square-planar configuration about the Ni atom. The Ni–β-CH2 bond (1.976(8)Å) is significantly shorter than the Ni–α-C bond (2.029(7)Å). The difference is explained by the contribution of polarized resonance structure in metal-olefin bonding.