Reatarding effect of nitrogen ylide for the polymerization of N-vinyl pyrrolidone

-Picolinium-p-chlorophenacylide (-PCFY) acts as a retarder for polymerization of N-vinyl pyrrolidone. The polymerization runs were carried out at 60°C using benzene as an inert solvent. The kinetic equation for the present system may be written asR _p [-PCPY]^–1.0 [AIBN]^0.66[N-VP]^1.0. The value of overall energy of activation for polymerization in presence and absence of-PCPY was computed as 44.0 and 42.3 kJ mol^–1, respectively. The inverse relationship ofR _p and¯M _v with-PCPY suggests that-PCPY acts as a polymerization retarder. The retarding effect is also evidenced by higher initiator exponent value and higher value of energy of activation in presence of ylide. A mechanism is also proposed in which polymer propagating chain combines with one ylide component to give resonance stabilized radical.     

Synthesis and magnetic properties of copper(II) bis(phenylsulphinyl)ethane complexes

Summary Two Cu^II complexes, [Cu₂(-L)Cl₄·H₂O (1) and Cu₂(-L)Cl₄ (2) [-L and -L = meso- and rac-PhS(O)(CH₂)₂S(O)Ph, respectively], were synthesized and characterized by elemental analysis, i.r. spectra and molar conductances. In each case, the Cu^II ion bonds to the 557-01 moiety through oxygen, and may be bridged by the ligand (-L or -L). From magnetic moment measurements at room temperature and variable temperature magnetic susceptibilities, we suggest that complexes (1) and (2) exhibit weak ferromagnetic behaviour.     

Reaction of benzylidene-2-naphthylamine with the ethyl ester of 3-pyridyl-β-oxopropionic acid

The reaction of benzylidene-2-naphthylamine with ethyl -(3-ethyl)--oxopropionate under various conditions gave the ethyl ester of -(2-naphthylamino)benzyl--(3-pyridyl)--oxopropionic acid, 1-(3-pyridyl)-3 phenylbenzo[f]quinoline, ethyl ester of 1-(3-pyridyl)-3-phenylbenzo[f]quinoline-2-carboxylic acid, and N-(2-naphthyl)amide of -(3-pyridyl)--oxopropionic acid. The IR, UV, and mass spectra of the products were studied and the pathways for their formation were discussed.Institute of Physical Organic Chemistry, Belorussian Academy of Sciences, Minsk 220603. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 807–810, June, 1996. Original article submitted December 30, 1995.     

Synthesis and Crystal Structure of N,N'-bis(2-aminoethyl)-2,4-pentanediiminatogold(III) Perchlorate

A synthetic procedure is described for N,N^'-bis(2-aminoethyl)-2,4-pentanediiminatogold(III) perchlorate. The complex was investigated by X-ray phase and X-ray diffraction analyses, electron spectroscopy, and IR spectroscopy. Crystal data for C₉H₁₉AuN₄Cl₂O₈: a = 10.093(2), b = 7.1740(10), c = 22.985(5) , = 90.35(3)°, V = 1664.2(5) ³, space group P2(1)/n, Z = 4, d _calc = 2.324 g/cm³. The structure consists of nearly planar acyclic cations [C₉H₁₉AuN₄]²⁺ and perchlorate anions [ClO₄]^–. The C–C and C–N bonds inside the -diiminate ring are delocalized. The parameters of the [C₉H₁₉AuN₄]²⁺ cation are compared with those in related complexes. The compound is stable in air for at least half a year; solubility in water is 0.8%.     

3-Aminoalkyl-5-methyl-benzo[b]thiophene

Zusammenfassung Ausgehend von -[5-Methyl-benzo[b]thienyl-(3)]-propionsäure wurde eine Reihe von 5-Methyl-benzo[b]thiophenen mit einer Aminoalkylsubstitution in 3-Stellung dargestellt: 3-(-Aminoäthyl)-5-methyl-benzo[b]thiophen durchCurtius-Abbau des Azids und 3-(-Aminopropyl)-5-methyl-benzo[b]thiophen sowie N-Substitutionsprodukte davon durch LiAlH₄-Reduktion der entsprechenden Amide.

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5-Methyl-benzo[b]thiophenes having an aminoalkyl substituent in position 3 were prepared from -[5-methyl-benzo[b]-thienyl-(3)]-propionic acid: 3-(-aminoethyl)-5-methyl-benzo[b]-thiophene byCurtius rearrangement of the azide, and 3-(-aminopropyl)-5-methyl-benzo[b]thiophene as well as some of its N-derivatives by reduction of the corresponding amides with LiAlH₄.

     

Triterpene glycosides from Pulsatilla chinensis

Four triterpene glycosides were isolated from the roots of Pulsatilla chinensis (Bunge) Regel (Ranunculaceae). Two new glycosides, chinensiosides A (1a) and B (2), were identified as 3-O-[-L-rhamnopyranosyl-(12)--L-arabinopyranosyl]-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid and 3-O-{-L-rhamnopyranosyl-(12)-[-D-glucopyranosyl-(14)]--L-arabinopyranosyl}-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid. The other two glycosides were identified as previously known hederasaponin C (3) from Hedera helix and glycoside III (4) from Pulsatilla cernua.     

The hydrolysis and fluoride complexation behavior of Fe(III) at 25°C and 0.68 molal ionic strength

Fe(III) hydrolysis and fluoride complexation behavior was examined in 0.68 molal sodium perchlorate at 25°C. Our assessment of the complexation of Fe(III) by fluoride ions produced the following results: log_F1 = 5.15₅, log_F2 = 9.10₇, log_F3 = 11.96, log_F4 = 13.7₅, where log_Fn = 5.15₅=[FeF _n ^(3-n)+ ][Fe³⁺]^–1[F^–]^–n. The stepwise fluoride complexation constants,FK _n+1, obtained in our work (where log_F K _n+1 =log_Fn) indicate that K _n+1/K _n =0.072±0.01. Formation constants for equilibria, Fe³⁺+nH₂OFe(OH) _n ^(3–n)+ +nH⁺, expressed in the form _n ^* [Fe(OH) _n ^(3-n)+ ][H⁺]ⁿ ,[Fe ³⁺]^-1, were estimated as ₁ ^* = –2.754, and ₂ ^* –7. Our study indicates that the results of previous hydrolysis investigations include very large overestimates of Fe(OH) ₂ ⁺ formation constants.     

Synthesis,chemical, and electrochemical characterization of the [Ag13{μ3-Fe(CO)4}] n− (n = 3, 4, 5) cluster anions: X-Ray structural determination of [N(PPh3)2]3 [Ag12(μ12-Ag){μ3Fe(CO)4}8]1

The oxidation of the [Fe(CO)₄]^2– dianion with Ag⁺ salts occurs through a particularinner-sphere mechanism, which involves an intermediate cascade of silver clusters stabilized by Fe(CO)₄ ligands. The last detectable Ag-Fe cluster of the sequence is the [Ag₁₃{-Fe(CO)₄}₈]^3– trianion, which has been selectively obtained by using ca. 1.7 equivalents of Ag⁺ per mole of [Fe(CO)₄]^2–. The [Ag₁₃{-Fe(CO)₄}₈]^3–- trianion has been isolated in a crystalline state with several quaternary cations, and has been characterized by X-ray diffraction studies of its bis(triphenylphosphine)iminium salt. [N(PPh₃)₂]₃ [Ag₁₃{ ₃-Fe(CO)₄}₈]·2(CH₃)₂CO, monoclinic, space group P2₁ (No.4),a = 16.284(2) Å,b =18.767(5) Å,c = 25.905(4) Å, = 90.46(1)°,V = 7916(3) ų,Z = 2,R = 0.0324. The molecular structure of the anion consists of a centered cuboctahedron of silver atoms with the triangular faces capped by Fe(CO)₄ units. Chemical reduction of ( Ag₁₃{ ₃-Fe(CO)₄}₈]^3– affords the corresponding [Ag₁₃{ ₃-Fe(CO)₄)₈]^4–, which in turn gives [Ag₁₃{ ₃-Fe(CO)₄)₈]^5– and [Ag₆{ ₃-Fe(CO)₄}₄]^– upon further reduction. Electrochemical investigations confirm the reversibility of the [Ag₁₃{ ₃-Fe(CO)₄}₈]^3–/4– redox change. Furthermore, in spite of some electrode poisoning effects, evidence of the existence of the [Ag₁₃{ ₃-Fe(CO)₄}₈]^5– pentaanion was obtained. The yet structurally uncharacterized [Ag₆{ ₃-Fe(CO)₄)₄]^2– dianion is quantitatively obtained by reaction of [Fe(CO)₄]^2– with ca. 1.5 equivalents of Ag⁺ or by addition of one equivalent of Ag⁺ to solutions of the [Ag₅{Fe(CO)₄}₄]^3– trianion. All attempts to isolate its quaternary salts as crystalline materials failed owing to formation of amorphous insoluble precipitates. The above series of ₃-Fe(CO)₄ octa-capped cuboctahedral Ag₁₃ clusters can be envisioned as the Ag⁺ . Ag and Ag^– cryptates of the [Ag₁₂{}₃-Fe(CO)₄}₈]^4– cryptand. respectively.Dedicated to Prof L. F. Dahl on his 65th birthday.     

Evidence of Ternary Inclusion Complexes Formation Using Factorial Design and Determination of Their Formation Constant

Evidence of the interaction among the [PbAc]⁺ and[PbEDTA]^-2 with the -cyclodextrin (-CD)is shown, using a 2⁴ factorial design. The factors used werethe [Pb(II)], [-CD], [Ac^-] and [EDTA] concentrationsat pH = 6.2. The statistical results indicate that the changes inchemical response for these species are associated to theinteraction among these factors. Spectrophotometric andelectrochemical studies were undertaken to assess the interactions.The equilibrium constants for inclusion complexes were determinedFor -CD-[PbAc]⁺ and -CD-[PbEDTA]^-2.     

Ab initio MP2 calculations of the products of acetylene addition to HgCl2

Gas-phase reaction of acetylene with HgCl₂ resulting in -chlorovinylmercury derivatives and their interaction with Cl^– and I^– anions and KI molecule was studied by the ab initio MP2 method with the Dunning—Hay double zeta basis set and LanL pseudopotential for Hg, K, and I atoms. The reaction was shown to proceed via a -complex of acetylene and HgCl₂ (the calculated enthalpy of formation is –6.5 kcal mol^–1). According to calculations, the activation energy of formation of cis--chlorovinylmercury chloride from acetylene and HgCl₂ is 31 kcal mol^–1. Chloride and iodide anions and KI molecule are readily added to both cis- and trans-isomer of -chlorovinylmercury chloride to give stable species.     

Synthesis,Structures, and Spectroscopic Characterizations of the α and β Forms of bis(N-Phenmethyl-benzimidazole-N) dichloro Cobalt(II) Complex: CoCl2(C7H5 N 2CH2Ph)2

Two modifications of the and forms of bis(N-phenmethyl-benzimidazole-N)dichloro cobalt(II) complex, CoCl₂(C₇H₅ N ₂CH₂Ph)₂, have been obtained by reacting N-phenmethyl-benzimidazole with CoCl₂ in different reaction solvents. X-ray analysis reveals that the two modifications have a similar molecular structure with different geometric parameters. The -form crystallizes in triclinic, P ^—1 space group and the form in the monoclinic, P2₁/c space group. The crystal structures of both consist of monomeric molecules of [CoCl₂(C₇H₅ N ₂CH₂Ph)₂] with slightly distorted tetrahedron geometry for the CoCl₂ N ₂ chromophore. They are also characterized by elemental analysis, i.r. spectrum, electronic spectrum, and thermogravimetric differential thermal analysis.     

Metal-betaine interactions. Part 17: A study of intradimer Cu · · · Cu distance variation in copper(II) betaine complexes containing [Cu2 (carboxylato-O,O′)4L2]n+ species

Four copper(II) complexes of betaines, [Cu₂(BET)₄Cl₂][Cu(BET)₂Cl₂]Cl₂ (2), [Cu₂(pyBET)₄Cl₂]₃[CuCl₄]₂Cl₂ (3), [Cu, (pyBET)₄ (H₂O)₂] (NO₃)₄ · 2H₂O (4), and [Cu₂(ppBET)₄(H₂O)₂](ClO₄)₄ · 4H₂O (5), (BET = Me₃N⁺CH₂COO^–; pyBET = C₅H₅N⁺CH₂COO^–; ppBET=C₅H₅N⁺CH₂CH₂COO^–), have been prepared and characterized by X-ray crystallography. These complexes all contain dimeric [Cu₂ (carboxylato-O,O)₄L₂] structures [basal Cu-O=1.955(4) 1.991(2), Cu Cu=2.602(1) 2.759(1) Å] with the apical ligand L=Cl^– in (2) and (3) [Cu-Cl=2.415(1) 2.436(3) Å] and L = H₂O in (4) and (5) [Cu-OH₂=2.158(4) 2.192(3) Å]; also present are a discrete [Cu(BET)₂Cl₂] molecule with a compressed tetrahedral CuO₂Cl₂ chromophore involving two unidentate carboxylate ligands [Cu-O=1.916(2), Cu-Cl=2.254(1) Å] in (2), and a discrete C_3v [CuCl₄]^2– anion in (3). Generally the intradimer Cu Cu distance may be correlated to the electronic repulsion of the metal-ligand bonds in the CuO₄L chromophore, as well as the steric interaction between the carboxylate moieties and the apical ligand.     

Eine Ringschlußreaktion zu Derivaten der β-{Benzo[b]thienyl(3)}-propionsäure

Zusammenfassung Acylierung von p-Methylthioanisol mit Bernsteinsäureanhydrid ergab -(2-Methylthio-5-methyl-phenyl)--oxo-buttersäure, welche mit Chloressigsäure zu -{2-Carboxy-5-methylbenzo[b]thienyl-(3)}-propionsäure ringgeschlossen wurde.Partielle Decarboxylierung lieferte -{5-Methyl-benzo[b]-thienyl-(3)}-propionsäure.Acylation of p-methylthioanisole by succinic acid anhydride gave -(2-methylthio-5-methyl-phenyl)--oxo-butyric acid, which reacted with chloroacetic acid to give -{2-carboxy-5-methyl-benzo[b]thienyl-(3)}-propionic acid.Partial decarboxylation yielded -{5-methyl-benzo[b]thienyl-(3)}-propionic acid.Herrn Prof.L. Schmid mit besten Wünschen zum 70. Geburtstag gewidmet.     

Anions of Transition Metals Carbonyls in Nucleophilic Vinyl Substitution: VII.2* Carbonylates Reaction with 1-Chloro-2-(trifluoromethyl)- and 1-Chloro-2-(perfluoro-tert-butyl)hexafluorocyclopent-1-enes,and with Z and E Isomers of ββ-Chloro-αα,ββ-difluorostyrenes. Halophilic and/or Nucleophilic Reaction mechanism2*2*

Reactions were studied between 1-chloro-2-(trifluoromethyl)-hexafluorocyclopent-1-ene with anions [CpFe(CO)₂]^-, [Re(CO)₅]^-, [Mn(CO)₅]^-, [CpMo(CO)₃]^-, and [CpW(CO)₃]^-. The effect of proton donors on the composition of reaction products was established. The reactions with [Re(CO)₅]^- and [Mn(CO)₅]^- were shown to proceed quantitatively along nucleophilic route (S_N2Vin) resulting in -vinyl complexes of rhenium and manganese. The [CpMo(CO)₃]^- and [CpW(CO)₃]^- anions turned out to be 10⁴ times less nucleophilic than [Mn(CO)₅]^-. In this case the main course of the reaction is the metal-halogen exchange with concurrent nucleophilic substitution. In reaction of [CpMo(CO)₃]^- and [CpW(CO)₃]^- with 1-chloro-2- (trifluoromethyl)-hexafluorocyclopent-1-ene the -vinyl complexes arise along an unusual autocatalytic mechanism: the reaction of carbonyl occurs not with the initial substrate but with pentafluoromethylcyclopent-1-ene that forms from the substrate under the action of a fluoride ion. In an extremely fast reaction of the same substrate with [CpFe(CO)₂]K the main process is carbonylate oxidation along unestablished mechanism. The reaction between carbonylates and 1-chloro-2-(perfluoro-tert-butyl)hexafluorocyclopent-1-ene proceeds exclusively as metal-halogen exchange that with [Re(CO)₅]^- furnishes anionic acyl complex cis[C₉F_{1 5}C(O)Re(CO)₄Cl]^-. The reaction of Z and E isomers of -chloro-,-difluorostyrenes with [CpFe(CO)₂]^- in the presence of proton donors confirmed the previously assumed (S_N2Vin) mechanism of nucleophilic substitution and also the intermediate formation of alkenyl carbanions in the parallel redox process.     

GC-FTIR and GC-MS in odour analysis of essential oils

The analysis of odour components in East Indian Sandalwood Oil (Santalum album L.) and in Patchouli Oil (Pogostemon cablin Benth.) based on GC-, GC-FTIR- and GC-MS-data resulted in the identification of-santalene,-santalal,-santalal, epi--santalal,-santalol,-santalol, (E)--santalol,-bergamotol and spirosantalol in Sandalwood Oil and of (–)-patchoulol,-guaiene,-patchoulene, seychellene,-bulnesene, norpatchoulenol and pogostol in Patchouli Oil as the most intense aroma compounds of these oils.     

Kinetic studies on the formation of ternary complexes in the reaction of diaquo-nitrilotriacetato-nickelate(II) and diaquo-anthranilato-N,N′-diacetato-nickelate(II) with amino acids in aqueous solution

Summary Kinetics of formation of ternary complexes from diaquo-nitrilotriacetatonickelate(II), [Ni(nta)(H₂O)₂]^–, and diaquoanthranilato-N, N-diacetatonickelate(II), [Ni(ada)-(H₂O₂] and amino acids have been studied by a pH indicator method using stopped-flow spectrophotontetry. The results conform to 1/k_obs=1/k+[H⁺]/kK·T_L, where K is the equilibrium constant for the formation of [Ni(A)(-L)(H₂O)]^2–(A=nta^3– or ada^3–) and k is the specific rate constant for the subsequent rate-determining ring closure leading to [Ni(A) (=L)]^2–. For the different amino acids, the k values decrease in the sequence: glycine>-alanine>L-phenylalanine>L-Valine>L-methionine>-alanine>sarcosine>N,N-dimethylglycine, and areca. 1000 times smaller than the k values for complexation of [Ni)(nta)(H₂O)₂]^– with monodentate ligands, such as NH₃ and imidazole. The spread of k values is much less than the pK_a values of the amino acids, and can be accounted for on the basis of the proposed mechanism. The relative rates are enthalpy controlled and high negative S values are commensurate with ring closure as the rate-determining step.     

The phenomenon of conglomerate crystallization. XX. Spontaneous resolution in coordination compounds. XVIII.

The title compound, [cis-Co(en)₂(NO₂)₂](NO₂) (1), crystallizes in the polar, nonenantiomorphic, monoclinic space group, Cc, with lattice constants:a=9.198(2) Å,b=12.444(2),c=9.963(3), and=96.76(2)°;V=1132.39 ų andd(calc;Z=4) =1.860 g cm^–3. Thus, with NO_2– as the counteranion, [cis-Co(en)₂(NO₂)₂] crystallizes in a heterochiral lattice containing racemic pairs of cations. A total of 2699 data were collected over the range of 4°270°; of these, 1859 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=15.465 cm^–1) and the relative transmission coefficients ranged from 0.9934 to 0.7112. Refinement was carried out for both lattice polarities and the finalR(F) andR _w (F) residuals were, respectively, 0.0242 and 0.0202 for (–––) and 0.0264 and 0.0243 for (+++). Thus, the former was selected as correct for our specimen.Unlike all previous X-ray diffraction studies of the structural properties of the cation [cis-Co(en)₂(NO₂)₂]⁺, which are found to have a pair of oppositely configured en rings [i.e., () or ()], we find that in1 the cations are in the lowest energy conformation and configuration; i.e., () or (). We attribute this change in configuration to the formation of strong interionic hydrogen bonds between nitrite anion oxygens and the axial—NH₂ hydrogens, which markedly weaken the intermolecular and intramolecular hydrogen bonds between ligand—NO₂ oxygens and the hydrogens of those same amine moieties. Thus, the nitrite anions behave exactly as nitrate anions, except that the hydrogen bonds found here are stronger than those formed by the latter. This is as expected since the negative charge is delocalized over two, instead of three, oxygens.     

α- andβ-Tri-ferricononatungstosilicate isomers

Summary Eight new compounds of the- and- M_aH_b[SiW₉Fe₃ (H₂O)₃O₃₇]·xH₂O type, where M = K, Me₄N, Et₄N or Na n-Bu₄N, and a + b = 7, have been synthesized from trivacant heteropoly tungstate- and- [SiW₉O₃₄]^10– precursors, and characterized by i.r., u.v., x-ray photoelectron (x.p.e.) and Mössbauer spectroscopy, and polarography, and by their magnetic moments and thermal behavior. The i.r. and u.v. spectra confirm that the-and- [SiW₉Fe₃(H₂O)₃O₃₇]^7– isomers possess the Keggin structure. The main i.r. bands shift regularly with the changes of cation-size. The charge transfer energies of the easily reduced-isomers are lower than those of the-isomers. The x.p.e. results indicate-bond back-donation between iron and oxygen. The Mössbauer parameters obtained for the-isomer show that the three iron atoms in the polyanion are of two types; the lower magnetic moments suggest the presence of anti-parallel coupling via iron d-orbitals overlap with the p-orbitals of the bridging oxygens. All compounds decompose atca. 600°C.     

Kinetics and mechanism of oxidation of aryl β-styryl ketones by osmium tetroxide in sulphuric acid-acetic acid medium. A structure-reactivity correlation study

Summary Oxidation of aryl -styryl ketones by osmium tetroxide has been studied in H₂SO₄-HOAc medium. The order with respect to osmium is unity in all the cases and the [substrate] order is unity for aryl -styryl ketone and fractional for substituted aryl -styryl ketone. Varying the concentration of [H⁺] at constant ionic strength had practically no effect on the rate; the salt effect is also negligible. Polymerisation did not occur when H₂C- CHCONH₂ was added to the reaction mixture. Increasing the percentage of AcOH decreased the rate. Direct attack at the 58-01 by Os^III in the slow step to give the oxidation product of aryl -styryl ketone, viz. 1-benzoyl-2-arylethane-1,2-diol is suggested and a possible mechanism for the reaction.     

X-Ray Diffraction Study of Piperidine Octamolybdate

Piperidine octamolybdate [C₅H₅NH₂]₄[Mo₈O₂₆]·4H₂O (I) has been synthesized and characterized by X-ray diffraction analysis. Crystals I are monoclinic, space group P2₁/n, a=12.892(3), b=9.283(2), c=19.184(4) , =92.50(3)°, V=2293.7(9) ³, Z=2,_calc = 2.317 g/cm³.