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Preferential formation of di- or trimers of methylenecyclopropane (MCP) under the influence of Ni(O) complexes is determined by the nature of ligands, additions of modifiers, and the reaction conditions. The Ni(O) complex with coordinated P(NEt2)3 was synthesized via a proposed intermediate catalytic system Ni(COD)2-P(NEt2)3 by the interaction between Ni(η3-C3H5)2 and P(NEt2)3. The composition of the complex: {Ni[P(NEt2)3]2x} (K-1) was established by1H and31P-1H NMR, EPR spectroscopy, IR diffuse reflectance spectroscopy, and GLC. In the range 20–60‡C complex K-l only brings about trimerization of MCP. The catalytic properties of K-l were described earlier by a proposed scheme for the catalytic conversion of MCP under the influence of Ni(O) complexes.

Ni(0), Ni(I), and Ni(II) complexes, differing in the ligand environment of the central atom, bring about di-, tri-, and oligomerization of spiro[2,3]-hex-1-ene (SH). The most efficient catalyst for the [2+2]-cyclodimerization of SH is NiBr(PPh3)3, which gives virtually a single product, the SH cyclo dimer. It has been found that high conversion and selectivity in the [2+2]-cyclodimerization of SH is achieved by using organoaluminum compounds as catalysts.

1. The19F-{1H} NMR spectra of a series of substituted 3- and 2-fluorophenyl benzyl ethers were investigated. 2. With respect to the effectiveness of the transmission of electronic influences of the substituents in the benzene group on the indicator fluorine atom in fluorophenyl benzyl ethers, the 3-fluorophenyl group is less informative than the 4-fluorophenyl group, while the 2-fluorophenyl; group gives no information.

1. The bridge group N(SO2C6H5) in compounds C6H5HgN(SO2C6H5)Ar is less capable of conducting the influence of the effect of conjugation of substituents in the aryl ring on the chemical shifts of199Hg in comparison with the -CH2- and -OC(O)- groups in the corresponding benzyl derivatives and phenylmercury benzoates. 2. Intramolecular coordinatation of o substituents in the N-aryl ring with the mercury atom leads to a strong unshielding of the199Hg nuclei. 3. The chemical shifts of the199Hg are sensitive to the steric effects of the alkyl groups at the N atoms in the compounds C6H5HgN(SO2C6H5)Alk.

1. A study was made of the absorption bands In the 1500–1750-cm−1 region of the spectra of o-carbonylcontaining phenols, and their phenylmercury and triethyltin derivatives, in polar and nonpolar solvents. 2. It has been shown that the carbonyl groups in these compounds coordinate with the phenylmercury and triethyltin groups. 3. The stability of chelate rings with formyl groups is characterized by the degree of breakdown of their coordinational bonding in coordinating solvents, decreasing with the acceptor capacity for the unshare delectron pair, i.e., in the order H>PhHg>Et3Sn. 4. In the case of competing substituents, the carbonyl group preferentially coordinates with the halide atom.

1. The haptotropic rearrangements in the chromium tricarbonyl complexes of 1-methylacenaphthene take place predominantly with retention of the stereochemistry, i.e., the exo-and endo-configuration of the interconverting complexes is preserved during the rearrangement. 2. The mechanism of the rearrangements observed in the chromium tricarbonyl complexes of naphthene and its analogs was established. It involves intramolecular migration of the organometallic group betwen the six-membered rings.

1. In DMSO, the logarithms of the constants of exchange equilibria with the participation of m- and p-substituted benzenesulfonanilides and their C6H5Hg derivatives show a linear correlation with the values of pKa of the benzenesulfonanilides. 2. This linear relationship is not observed when, substituents capable of steric and intramolecular coordination interactions are present close to the key nitrogen atom.

1. PMR methods have been used to show that the rate of exchange in the (CH3)3SnCl+ (CH3)3SnSR system in toluene solution varies inversely with the temperature. 2. At room temperature and below, the rate of exchange depends on the nature of the R radical, increasing in the order: 2,6-(CH3)2C6H3; 3,4,5-Cl3C6H2 < 3-ClC6H4 < C6H5 < 4-(CH3)2NC6H4 < CH3.

1. A study has been made of exchange reactions involving the (C6H5)3C, (C6H5)3Ge, and organometallic derivatives of the thiophenols. 2. The (C6H5)3C and (C6H5)3Ge groups of the thiophenol derivatives are less inclined to intramolecular exchange than are the C6H5Hg, (C6H5)3Sn, and (C6H5)3Pb groups. 3. The geometrical conditions imposed in nonvalence interaction with the o-CH3 group are more restrictive for the (C6H5)3CS and (C6H5)3GeS groups than for C6H5HgS, (C6H5)3SnS, and (C6H5)3PbS. 4. Intramolecular coordination bonding could not be detected in triphenyltin o-chlorothiophenolate, at least within the sensitivity of the methods used here for studying exchange equilibria.

1. The position of the tautomeric equilibrium for 2-substituted nitrosophenols and their organometallic derivatives in toluene is related to the ability of the OH and RnMO groups to form chelate rings with a halogen atom or MeO group. The stabilization of the nitroso form due to this effect is the greatest for the PhHg grouping. 2. For the compounds with a sufficiently strong intramolecular hydrogen bond or intramolecular coordination bond, a change to solvating solvents (THF, DMSO) shifts the equilibrium toward the quinone oxime form. 3. In DMSO and HMPA, the nitroso form of the organometallic derivatives of 2,6-dibromo-4-nitrosophenol is largely or completely ionized.

1. The intramolecular contribution to the splitting of the NQR frequencies in the 2,6-dihalo-4-X-derivatives of phenol has been separated out. The strength of the intramolecular hydrogen bond is substantially dependent on the nature of the substituants in position 4. The splittings in the NQR spectra are reduced upon passing from electron-accepting substituents to electron-donating substituents. 2. The intramolecular coordination interactions of mercury atoms with halogen atoms leads to a reduction and splitting of the NQR frequencies of the halogen atoms in positions 2 and 6 and they are only slightly dependent on the substituent in position 4.

The transmission of electronic effects of substituents in a number of arylmercury derivatives of 4-fluorobenzenesulfonanilides in inert and coordinating solvents has been studied by the19F NMR method. The binuclear bridge grouping Hg-N transmits electronic effects of substituents more strongly than an Hg bridge atom. The coordination interactions with the solvent substantially lower the transmission capacity of both mononuclear and binuclear organomercury systems, the quenching effect on the transmission of electronic effects of the substituents being considerably greater in the first case.

1. Electron-donor substituants in an aryl radical of symmetric diaryltriazenes (DAT's) accelerate the prototropic process in these compounds, while electron-acceptor substituents have the opposite effect. 2. In solutions of DAT's prototropic transfer is realized according to a bimolecular mechanism with the formation of a cyclic transition state with delocalized bonds in THF and according to an intramolecular mechanism with the formation of solvated ion pairs in Py.

1. Simultaneous condensation of chromium vapors with the vapors of two substituted benzenes, one of which was fluorobenzene, gives substituted dibenzenechromium complexes of the type (C6H5F)Cr(C6H5X). 2. The values of the19F chemical shifts correlate satisfactorily with the σm+ and σmp substituent constants.

1. It was established by the19F NMR method that the bridging mercury atom in compounds of the ArHgC6H4F-4 and ArCH2C6H4F-4 type transmits the electronic effects of substituants less effectively than the CH2 group. 2. The decrease in the transmission power of the mercury atom in polar coordinating solvents results mainly from coordination interactions.

1. The modifying H2 and CO treatment of the Fe-Cr and Fe-Cr-Cu conversion and desulfurization catalysts is accompanied by the formation of a nonstoichiometric magnetite structure which is catalytically active in the synthesis of organic compounds from CO and H2O. The stability of the phase to oxidation in air is apparently due to the stabilizing effect of the incorporated carbon atoms. The oxides of chromium and copper perform primarily the function of the structure-forming promoters. 2. During the modifying action of H2 and CO on the finely dispersed iron oxide phases localized in the pores of the substrates (kieselguhr, kaolin), the iron ions aggregate and form large blocks of a substituted ferrite phase stable to oxidation. The catalytic activity of ferrite in the synthesis reactions is greater than the activity of the above-mentioned catalysts.

1. Electronic spectroscopy has been used to show the similarity of the reactions of the nitrophenols and their phenylmercury and triphenyltin derivatives with triethylamines and diethylamines. 2. Increasing the electron-acceptor activity of the aromatic ring substituent in the nitrophenol or the donor activity of the amine, or altering the polar properties and coordinating ability of the solvent, will shift the complexing equilibrium toward ion pair formation, and by promoting ionization, bypass the stage of molecular complex formation. 3. Data has been obtained on these reactions, and it has been shown that the formation constants for ion pairswith triethylamine fall off in the order: H > SnPh3 > HgPh.

A linear equation is presented for determining, from the chemical shift of19F in a p-fluorophenyl group, the effective charge of that CH fragment of the original aromatic molecule the carbon atom of which is bonded to the fluorophenyl indicator group. It has been shown that for a cyclic aromatic 6π-electron system determination of the effective charges of the CH fragments by quantum-chemical calculations and the evaluation of this charge from the19F chemical shift of the corresponding p-fluorophenyl substituents lead to coincident results.

The electron effects of substituents in an acetylenic residue and in organometallic radicals on the position of metal-metal and metal-proton exchange equilibria in toluene were studied by /sup 19/F-//sup 1/H/ NMR for systems containing substituted acetylenes and/or their organometallic derivatives. An increase in electron-acceptor properties of the substituent destabilizes the less polar hydrogen-carbon or metal-carbon bonds to a greater extent than the more polar metal-carbon bonds; the differences increase with increasing difference in the polarity of the corresponding bonds in the sequence cyclo-C/sub 6/H/sub 11/Hg < PhHg < Ph/sub 3/Pb < Ph/sub 3/Sn.

1. An electrochemical synthesis of acetylcymanthrene from 1,1′-diacetylferrocene and dimanganese decacarbonyl was carried out. 2. It was proposed that the electrochemical reduction of acetyl derivatives of ferrocene, cymanthrene, and benzenechromium tricarbonyl in CH3CN, leading to cyanoalkyl compounds, be used as a method for elongating the side chain of the above π-complexes by two C atoms. 3. It was shown that as in the case of ferrocene, the ferrocenyl radicals can be electrochemically alkylated.

1. On the basis of an investigation of19F-{1H} NMR spectra of a series of 4-fluororphenolates of triaryltins, Ar3SnOC6H4F-4, it has been established that the transmission ability (TA) of the SN-O binuclear bridge grouping differs slightly from that of the Sn bridge atom and the CH2O group. 2. In contrast to the weak proton-donor solvent CHCl3, aprotic polar solvents — either noncoordinating or coordinating — reduce the electron conductivity of Ar3SnOC6H4F-4.

New olefinic complexes of zerovalent nickel containing 2, 2-dimethyl-1-methylenecyclopropane and 1,3,3-trimethylcyclopropene as ligands and stabilized with triphenylphosphine were synthesized.

1. The equilibrium NH acidities of benzenesulfonamide and its derivatives have been studied by the transmetallation method in DMSO. 2. Linear relationships connecting the pK values of benzenesulfonamides C6H5SO2NHR with the σ* constants of alkyl groups R and of substituted benzenesulfonanilides C6H5SO2NHC6H4R′ with the σ constants of the substituents R′ have been found. The acidifying effect of the phenylsulfonyl group on its introduction into aniline and into 4-aminopyridine has been evaluated. 3. A linear relationship has been established between the pK values of anilines and 4-anilinopyridines substituted in the amino groups, and on this basis the presumed pK values of a number of aminopyridine derivatives in DMSO have been calculated.

It has been established that there is no significant difference in the transmission ability of the binuclear bridging group Sn-CH2 and the bridging atom Sn. The effectiveness of the transmission of electronic effects of substituents through the tin-containing bridging groups Sn-CH2 and Sn is considerably reduced in a coordinating solvent medium, while for both bridges the “suppression” of the electronic conduction effect is approximately the same.

1. Comparison of electronic spectra has brought out the effect of polar and conformational factors in the behavior of the organometallic derivatives of the nitrophenols and nitrothiophenols. 2. Interaction of these compounds with DMSO does not lead to the formation of ion pairs, but rather results in the establishment of equilibria between molecular complexes and ions. 3. The values of the constants for complexing with DMSO fall off in the order: ArSHgPh > ArSH, ArSSbPh2 > ArSPbPh3 > ArSSbPh4 > ArSSnPh3. 4. The dissociation constants for the various compounds fall off in the order: ArSSbPh4 > ArSSnPh3 > ArSH > ArSPbPh3, ArSSbPh3. The nitrothiophenolate of phenylmercury does not dissociate in DMSO.

1. Exchange reactions of diphenylantimony 2,6-dimethylthiophenolate with thiophenol and its (C6H5)3Sn- and C6H5Hg-derivatives in chlorobenzene and the exchange of tetraphenylantimony 2-methylthiophenolate with 2-methylthiophenol and its C6H5Hg-, (C6H5)3Sn-, and (C6H5)3Pb-derivatives in chloroform were studied. 2. The migration ability of organometallic groups of the RnM type in derivatives of thiophenols in chlorobenzene and chloroform increases in the series: (C6H5)3Sn < (C6H5)3Pb ≈ (C6H5)2Sb < C6H5Hg < (C6H5)4Sb. 3. The position of the exchange equilibria of tetraphenylantimony 2-methylthiophenolate with substituted tetraphenyltin thiophenolate depends greatly on the polar and steric effects of the substituents in the thiophenol ring. 4. The (C6H5)4SbS group possesses greater space requirements than the (C6H5)3SnS, C6H5HgS, (C6H5)3PbS, and (C6H5)2SbS groups in uncoupled interactions with the o-CH3 group.

1. A19F-{1H} NMR study was carried out on the effect of the nature of the key element of HX acids [X=SPh and N(SO2Ph)Ph] on the position of the equilibrium of exchange reactions in solutions of mixtures containing the HX acid, 4-fluorophenylacetylene, and/or their organo-metallic derivatives in toluene and DMSO. 2. The ratio of the dissociation constants of the Q-N bonds to the dissociation constants of the Q-C bonds increases in the series: Ph3Pb > H > Ph3Sn > cycle C6H11Hg > PhHg.

1. The complexes ArNiXL2 and HNiXL2 (X is halide, L is tertiary phosphine) in the presence of zinc catalyze the condensation of bromobenzene with styrene (stilbene formation). 2. The yield of stilbene and 1,3-diphenylbutene, the dimerization product of styrene, in the presence of pyridine is lowered according to the substitution of phenyl groups on the phosphorus ligand L by alkyl (ethyl, cyclohexyl) groups. 3. Change of triphenylphosphine to phenylethylphosphines and tricyclohexylphosphine in the hydride complex HNi(X)(PR3)2, the catalytic activity of which falls in the order X=Cl−≫Br−>I−, favors the dimerization of styrene in the absence of pyridine.

1. The polar effects of the substituents in the thiophenol ring have little effect on the position of the exchange equilibria of the metal-proton and metal-metal type involving substituted thiophenols and their C6H5Hg, (C6H5)3Sn, and (C6H5)3Pb derivatives. 2. Depending on the acceptor of the unshared electron pair, in o-substituted thiophenols and their organometallic derivatives the stability of the chelate rings in most cases increases in the order (C6H5)3Sn

1. In a comparative Investigation by the19F NMR method of two series of model compounds of the type of ArQN(SO2Ph)C6H4,F-4 (Q=Hg, CH2), it was established that the Hg-N binuclear bridge grouping (BNG) possesses a greater transmission capacity (TC) than the CH2-N BNG. 2. The efficiency of the transfer of the electronic influence of substituents to an indicator F atom through the Hg-N BNG depends substantially on the direction of transmission. 3. The decrease in the TC of the Hg-N BNG in coordinating solvents is the result of both dipole-dipole and coordination interactions with the solvent the contributions of which are practically equal.

1. In the presence of (η2-methylenecyclopropane)bis(triphenylphosphine)nickel (Kt-1), methylcyclopropane (MCP) undergoes dimerization, trirmerization, and oligomerization, the formation, of trimers being predominant. In catalytic conversions of MCP under the influence of Kt-1, we have found for the first time in the composition of the dimers 2-methyl-4-methylene-1,5-hexadiene. It has been established that this dimer is also formed in the case of the catalytic system Ni(COD)2-PPh3. 2. Dimers and trimers of MCP that are formed, containing diene fragments, are the principal predecessors of higher oligomers. Conditions have been found for reducing the yield of oligomers from 45–56% to 4–6%, thus increasing the selectivity of the process in the direction of monoolefins and triolefins with cyclopropyl substituents

1. Study has been made of the IR and UV spectra of various substituted o-nitrophenols and o-nitrothiophenols, and their organomercury and organolead derivatives, in polar and nonpolar solvents. Constants for the complexing of these compounds with pyridine, DMSO, and hexamethylphosphorotriamide in benzene solution have been determined. 2. It is suggested that the strength of the intramolecular coordination bond could be determined through the ratio of the constants for complexing of the p- and o-substituted derivatives with coordinating reagents. 3. The coordination bonding between the PhHgO, PhHgS, and Ph3PbS groups and the o-nitro group is weak, being of the order of 1 kcal/mole or less.

1. Ferrocene reacts with bromoadmantane in the presence of A1Cl3 to give mono- and 1,1′-diadamantylferrocene. 2. Acylation of adamantylferrocene with raonoethyl o-phthaloyl chloride takes place in the 3-position of the substituted ferrocene ring, and to some extent in the free cyclopentadienyl ring.

1. Exchange equilibria of the metal-proton and metal-metal type were studied by the method of IR spectroscopy in a series of substituted phenols and their C6H5Hg and (C6H5)3Sn derivatives. 2. The polar effects of substituents in the phenol ring change the position of an equilibrium of the metal-proton type and practically do not influence an equilibrium of the metal-metal type. 3. Depending on the nature of the acceptor of the unshared electron pair, the strength of the intramolecular coordination bond with o-halogens increases in the series: (C6H5)3Sn< H< C6H5Hg. 4. The C6H5Hg group is a milder Lewis acid than (C6H5)3Sn. 5. The differences in the strength of the chelate rings with the participation of the (C6H5)3Sn group and the H-atom of hydrogen increases sharply for six-membered rings formed by NO2 and CHO groups.

On investigation the19F-{1H} NMR spectra of two series of model compounds of type ArQN(SO2Ph)C6H3Br-2-F-4 (Q=Hg, CH2) it was established that participation of the Hg bridging atom in intramolecular coordination interactions with the ortho Br atom led to a reduction in the transmissability of the binuclear Hg-N bridging groupings.

19F and199Hg NMR have been used to investigate the comparative influence of electronic effects of the substituents on the shielding of19F and199Hg nuclei in ArHgC-CC6H4F-4 and 4-FC6H4HgC=CR. It has been found that the shielding of the fluorine decreases and the shielding of the mercury increases with increasing electron-acceptor properties of the Ar or R, or when the change is made from toluene to pyridine. The19F and199Hg chemical shifts correlate well with the σ and σ0 Hammett constants.

1. For tin-containing complexes of 3,6-di-tert-butyl-o-benzoquinone, the parameters of the ESR spectra (HFI with ring protons and with117Sn and119Sn nuclei) and the distribution of spin density in the free-radical ligand depend on the nature of the substituents on the Sn atom. 2. The frequency of “stannotropic” migration in the radicals that we have investigated is determined by the strength of the Sn-O bond, the coordination unsaturation of the Sn atom, and the spin density on the univalent O atom; as these latter factors become more important, pentacoordinated structures appear, with equivalent Sn-O bonds. 3. The polarity of the medium determines the direction of the reaction of ligand substitution in the interaction of the o-quinone with organic monochlorotin compounds; in nonpolar media, the organic ligand is replaced, and in polar media (DMSO), the Cl atom is replaced.

1. The rate of exchange between trimethyltin chloride and thiophenolate in THF and pyridine solutions increases with an increase in the solvating action of the solvent. 2. The data on the high-temperature exchange in THF solution departs from the linear In (1/Τ) vs 103/T relation. 3. Addition of small quantities of pyridine to the toluene solution increases the rate of exchange, the increase being directly proportional to the pyridine concentration. 4. This is the first reported instance of an organometallic exchange reaction in which passage from an inert solvent to a coordinating solvent can either increase or reduce the reaction rate, depending on the temperature.

1. In o-chloromercuryphenols there is no intramolecular hydrogen bond with the HgCl group, while the OH group is primarily in the trans-position with respect to it. 2. An increase in the ability for autoassociation of o-chloromercury derivatives of phenol was established. The ability to form hydrogen bonds with coordinating solvents was evaluated quantitatively.

1. The introduction of substituents into the meta and para positions of the thiophenol ring in phenylmercury derivatives of thiophenols results in an increase in mercury shielding. 2. The presence of intramolecular coordination bonding between the metal atom and ortho substituents is demonstrated. 3. Coordinating and polar solvents increase mercury shielding.

1. A comparative19F NMR study of a series of model ArN(X)SO2C6H4F-4 compounds (X=H, HgPh, and Na) showed that the mechanism for the transmission of the substituent electronic effects in these compounds depends on the polarity of the Nδ−-Xδ+ bond. An increase in this polarity leads to an increase in the relative contribution of direct polar conjugation. 2. The specific solvation of the mercury atom in the binuclear bridging N(HgPh)SO2 group has only a slight effect on its transmission capacity.

1. We have examined the spectral characteristics of the absorption bands in the 1550–1750 cm−1 region of p-carbonyl-containing phenols and the corresponding organometallic derivatives in nonpolar and polar solvents. 2. The capacity for self-association of p-carbonyl-containing compounds falls in the order H > SnPh3 > PbPh3 > HgPh for different classes of compounds. 3. When conjugation between the R3SnO group and the CH3CO substituent is possible self-association of p-R3SnOC6H4COCH3 is more facile than association of R3SnOAr and ArCOCH3. 4. These compounds have the benzenoid structure in polar and nonpolar solvents. The intensity of the benzene ring modes varies in an order corresponding to the change in the electron-donating properties of the RnM groups: Ph3Pb ≥ SnEt3 > HgPh > SnPh3 > H. 5. The magnitudes of σ R o of these groups calculated from thev Ar intensity by Katritzky's method are not constant but depend on the p-substituent and the solvent.

1. Spectral and thermodynamic characteristics of H-complexes of phenol with phenyl- and ferrocenylphosphines and the corresponding phosphine oxides were determined. 2. The strength of the H-bonds increases upon replacement of the phenyl groups by ferrocenyl groups in the series: Ph3 < FcPh2 < Fc2Ph < Fc3. 3. The proton-acceptor ability of the ferrocenyl-substituted phosphines and phosphine oxides was found to be greater than in the case of the corresponding trialkyl-substituted derivatives. 4. The anomalously high donor properties of the Fc substituents are tentatively explained as hyperconjugation of the π-orbitals of rings with σ-bonds of phosphorus atom and the phosphoryl group.

1. The19F-{1H} spectra of a series of 4- and 4′-fluoroaryl benzene ethers ArCH2OC6H4F-4 and ArOCH2C6H4F-4 were investigated. 2. The transmission power of the binuclear bridging group -CH2O- differs little from that of the CH2 group. 3. The effectiveness of the transmission of the electronic effects of the substituents in ArCH2OAr′ depends on the direction of transfer and is highest in the case where the oxygen atom is near the variable substituent. 4. Unlike the proton-donating chloroform, aprotic polar solvents reduce the electron conduction of ArCH2OC6H4F-4.

1. It has been shown that in the presence of (η2-methylenecyclopropane)bis(triphenyl-phosphine) nickel (Kt-1) and of a series of triphenylphosphine Ni(O) complexes the catalytic conversion of methylenecyclopropane (MCP) proceeds with the formation of identical di- and trimerization products. It is postulated that the mechanism of di- and trimerization of MCP on all Ni(O) phosphine complexes is similar, with the formation of Kt-1 as a general intermediate. 2. Complexes of Ni(I) and Ni(II) which have been studied were found to be inactive in MCP conversion.

1. A study has been made of the effect of concentration and temperature on the rate of exchange in the (CH3)3SnCl+(CH3)3SnSC6H5 system in toluene. The reaction rate has been found to vary inversely with the temperature. 2. It is suggested that exchange between trimethyltin chloride and thiophenylate in inert medium proceeds through the formation of six- and eight-membered cyclic transition states with delocalized bonds.

1. In a comparative investigation by the19F-{1H} NMR method of a series of mono- and binuclear bridge systems containing 3- and 2-fluorophenyl indicator groups ArHgC6H4F-3(2) and ArHgN(SO2Ph)C6H4F-(2), it was established that in both types of systems the chemical shift (CS) of fluorine in the 3 position, in contrast to the CS of fluorine in the 2 position, is determined chiefly by the electronic influence of the substituents. 2. The 3-fluorophenyl indicator group in the compounds studied is less sensitive to the electronic influence of substituents than the 4-fluorophenyl group. 3. In the presence of the effects of π- or σ,π-conjugation along the bonds of the bridge atom to the aromatic ring, the comparative transmission capacity of the bridge groups may vary with changing position of the indicator group in the aromatic ring.

1. The formation of (η2-methylenecyclopropane)bis(triphenylphosphine)nickel was established in the reaction of methylenecyclopropane (MCP) with Ni(PPh3)3, Ni(PPh3)4, and the catalyst (Cat) obtained by the reduction of NiCl2·6H2O by sodium borohydride in the presence of PPh3. 2. 31P-{1H} NMR spectroscopy was used to determine that the catalyst was composed of Ni(PPh3)3, Ni(PPh3)4, and, probably, Ni(PPh3)2. 3. Interconversions of the catalyst and (η2-methylenecyclopropane)bis(triphenylphosphine)nickel were determined during the transformations of MCP, which supports the scheme for the catalytic cycle of MCP reactions by the action of Ni(O) triphenylphosphine complexes.