Mass-spectrometric study of 3,9-diazabicyclo- and 3,9-oxaazabicylo[3.3.1]nonanes

The mass spectra of substituted 3,9-diazabicyclo- and 3,9-oxaazabicyclo[3.3.1]-nonanes were studied as a function of competitive distribution of the charge between the N₃ and N₉ and O₃ and N₉ atoms and the properties of the substituents attached to the heteroatoms. It is shown that a characteristic peculiarity of the fragmentation of 3,9-diazabicyclo[3.3.1]nonanes is fragmentation of the molecular ion with an open structure that is formed by cleavage of the C₁-C₂ bond. The formation of an amine fragment with retention of the bicyclic structure with an exocyclic double bond attached to the quaternary N₉ atom is characteristic for 3,9-oxaazabicyclo[3.3.1]nonanes. It is shown that this sort of behavior of the investigated compounds is determined by their structures and the properties of the heteroatoms in the saturated bicyclic systems.Communication 12 from the series Application of mass spectrometry in structural and stereochemical studies. See [1] for Communication 11.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 229–235, February, 1981.     

Mass spectra of derivatives of benzaldehyde selenazolylhydrazones

The mass spectra of benzaldehyde selenazolylhydrazones Ia-d and benzaldehyde selenazolidenehydrazones II and III were studied. Splitting out of benzonitrile as a result of a rearrangement of the McLafferty type is characteristic for the fragmentation of the M⁺ ions of Ia-d. The subsequent fragmentation of the M — C₆H₅CN ion occurs due to ejection of the SeH group or a molecule of carbodiimide from the selenazole ring or due to cleavage of ring side substituents. The principal fragments in the mass spectra of II and III are formed as a result of the ejection of groups of SeH and SeCHCO atoms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 762–764, June, 1982.     

Hydrolysis of 2-acetyl-substituted fluoroalkyl 3-ketoesters

Conclusions Fluoroalkyl 2-acetyl-3-ketoesters are hydrolyzed by a) aqueous KOH regioselectively with cleavage of the C²-C³ bond, b) aqueous ethanolic KOH and aqueous pyridine with cleavage of the C²-C³ and C²-C⁴ bonds, and c) in neutral aqueous and acid media with cleavage of the C¹-C² and C²-C⁴ bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2112–2113, September, 1987.     

Die Umsetzung von Diphenylphosphinigsäurechlorid mit Natriumsalzen von aromatischen Sulfinsäuren zu Diphenylphosphinsäure-S-arylestern

Zusammenfassung Die Umsetzung von Diphenylphosphinigsäurechlorid mit Alkalisalzen aromatischer Sulfinsäuren führt unter Reduktion am Schwefel, Oxydation am Phosphor und Ausbildung einer Bindung zwischen Phosphor und Schwefel, zu Diphenylthiophosphinsäure-S-arylestern: (C₆H₅)₂P(O)–S–Ar (Ar=C₆H₅, 4-CH₃C₆H₄, 4-ClC₆H₄, 2-Cl-5-CH₃-C₆H₃, 2-C₁₀H₇). Die besten Ausbeuten (40–85%) wurden mitDMF als Lösungsmittel erhalten. Aliphatische Phosphinigsäurechloride geben keine Bindung zwischen P und S. Ebenso tritt keine Umsetzung ein, wenn im Säurechlorid eine P–O-Struktur vorliegt. Auch die Umsetzung von (C₆H₅)₂PCl und (C₆H₅)₂P(O)Cl mit Sulfonsäuren anstelle der Sulfinsäuren führt zu keiner P–S-Verknüpfung. Diese Phosphor-Schwefel-Bindung in den Thiophosphinsäure-S-estern stellt die schwächste Stelle im Molekül dar, da ein hydrolytischer, oxydativer oder reduktiver Angriff diese Bindung wieder löst.

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Reaction of diphenylchlorophosphine with alkali salts of aromatic sulfinic acids leads to diphenylthiophosphinates; reduction occurs at the sulfur atom, oxidation at the phosphorus atom and a bond between phosphorus and sulfur is formed: (C₆H₅)₂P(O)–S–Ar, Ar=C₆H₅, 4-CH₃C₆H₄, 2-ClC₆H₄, 2-Cl-5-CH₃-C₆H₃, 2-C₁₀H₇. The best yields were obtained in dimethyl formamide as solvent. With aliphatic chlorophosphines no bond formation beetween sulfur and phosphorus occurred. Similarly no reaction was observed, when a phosphorus atom in a higher state of oxidation was present, as for example in diphenylphosphonylchloride. Also, no reaction took place when sulfonic instead of sulfinic acids were used. The weakest bond found to exist in the diphenylthiophosphinates was the P–S-linkage, which readily undergoes hydrolytic, oxidative or reductive cleavage.

     

Substituent effect in hydrogenative ring-opening of cyclobutanes on Pt/SiO2

The main direction of hydrogenative ring-opening of propylcyclobutane on Pt/SiO₂ catalyst in the temperature interval of 373–673 K is the formation of n-heptane through cleavage of the sterically hindered C₁–C₂ bond. The unusual selectivity can be attributed to adsorption of both the ring and the propyl group on the catalyst. With increasing temperature, the selectivity of ring-opening approaches the statistically expected ratio.     

Synthesis,Characterization and Crystal Structures of New Ruthenium Carbonyl Clusters Derived from (9-Anthracenyl)diphenylphosphine*

Thermal reaction of [Ru₂(CO)₆(μ-PFu₂)(μ-η¹,η²-Fu)] (Fu=2-furyl) with (9-anthracenyl)diphenylphosphine (AnPPh₂) produces a novel diruthenium complex [Ru₂(CO)₅(μ-PFu₂)(μ-η¹,η¹,η²-C₁₄H₈PPh₂)] (1) in good yield whereas the corresponding reaction between [(μ-H)₄Ru₄(CO)₁₂] and AnPPh₂ gives [HRu(CO)₃(PPh₂C₁₄H₈)][(μ-H)₄Ru₄(CO)₁₁(AnPPh₂)] (2). Both compounds 1 and 2 were fully characterized by spectroscopic methods and their X-ray crystal structures were determined. For 1, initial coordination of the PPh₂ functionality at the Ru atom is accompanied by cyclometalation of the anthracenyl ring to form a Ru–C σ bond together with concomitant formation of a π bond to the adjacent Ru center and loss of the furyl ligand. The formation of 2 involves the cleavage of two Ru–Ru bonds, and the making of a Ru–P bond, followed by orthometalation of the anthracenyl ring. The optical absorption and emission spectra of 1 were recorded and the results were correlated to the DFT calculations.Dedicated to Professor F. Albert Cotton on the occasion of his 75th birthday.     

Oxidation of secondary cycloalkanols by the lead tetraacetate-metal halide system

Conclusions Secondary cyclic alcohols with C₅-C₈ ring size are oxidized by the lead tetraacetate-metal chloride or bromide system in three directions: with ring cleavage and the formation of -haloalkanals and without ring cleavage with the formation of the corresponding ketones and also, for C₇-C₈, 1,4-epoxycycloalkanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2538–2542, November, 1988.     

Field ionization and electron impact mass spectra of cycloolefins

The field ionization mass spectra of monosubstituted cyclopentenes and cyclohexenes with C₁-C₇ n-alkyl and C₄-C₅ isoalkyl substituents in positions 1 and 3 have been investigated and compared with the previously reported electron impact mass spectra of these compounds. The cleavage of the C? C bond β to the double bond in the non-isomerized molecular ion was found to be a typical degradation reaction of the higher homologues in the strong electric field. So, by means of the field ionization mass spectra, the >C₁ alkyl substituent can be readily located in the parent molecule. The electron impact mass spectra exhibit a less specific fragment ion distribution for positional isomers due to the extensive molecular ion isomerization prior to decomposition, but provide useful information on the ring size. For structure determination it is appropriate to use both ionization techniques.     

Mass spectra of some sesquiterpene lactones of the eudesmane series with a C1-OH group

Summary The fragmentation of some C₁-OH eudesmanolides has been studied with the aid of an isotopic label and high-resolution mass spectrometry. It has been shown that the most characteristic fragmentation is that with the cleavage of the C₁-C₁₀ and C₄-C₅ bonds. The sesquiterpene lactone arabsin has also been assigned to the C₁-OH eudesmanolides and this has been confirmed by its conversion into anhydroarabsin — an ,-unsaturated ketone.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 34–40, January–February, 1979.     

VUV photoionisation of free azabenzenes: Pyridine, pyrazine, pyrimidine, pyridazine and s-triazine

Photoionisation mass spectrometry was used to obtain the fragmentation pathways of pyridine, pyridazine, pyrimidine, pyrazine and s-triazine molecules upon absorption of 23.0, 15.7 and 13.8 eV synchrotron photons. The ionic fragments observed vary from molecule to molecule, however C₂H₂⁺, HCN⁺and HCNH⁺ are common to all five molecules at the three photon energies. Furthermore, the presence of C₂H₂N₂⁺, C₃H₃N⁺ and C₄H₄⁺ in the spectra of some of the molecules suggests dissociation pathways via loss of HCN moieties. The respective parent cations, m/q=79, 80 and 81 have a greater yield at low photon energies when compared to the most intense fragment peak in each spectra. We recorded two of the fragment cation yields, as well as the parent photoion yield curves of pyridine, pyridazine, and pyrimidine in the 8–30 eV range. The formation of abundant cation fragments show a strong propensity of the molecules for dissociation after the absorption of VUV photons higher than 14 eV. The differences in relative fragment yields from molecule to molecule, and when changing the excitation energy, suggest significant bond rearrangements and nuclear motion during the dissociation time. Thus, bond cleavage is dependent on the photon energy deposited in the molecule and on intramolecular reactivity. With the aid of photoion yield curves and energy estimations we have assigned major peaks in the spectra and discussed their fragmentation pathways.     

Massenspektrometrische Untersuchungen an Organophosphorverbindungen. II—Elektronenstoßinduzierte Fragmentierungen von Tetraorganodiphosphandisulfiden

The behaviour under electron impact (70 eV) which includes some rearrangement processes of some tetraorganodiphosphanedisulfides R₂P(S)-P(S)R₂ (R ? CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, C₃H₅, C₆H₅) and CH₃RP(S)–P(S)CH₃R (R ? C₂H₅, n-C₃H₇, n-C₄H₉, C₆H₅, C₆H₅, C₆H₅,CH₂) is reported and discussed. Fragmentation patterns which are consistent with direct analysis of daughter ions and defocusing metastable spectra are given. The atomic composition of many of the fragment ions was determined by precise mass measurements. In contrast to compounds R₃P(S) loss of sulphur is not a common process here. The first step in the fragmentation of these compounds is cleavage of one P–C bond and loss of a substituent R?. The second step is elimination of RPS leading to [R₂PS]⁺ from which the base peaks in nearly all the spectra arise. The phenyl substituted compounds give spectra with very abundant [(C₆H₅)₃P]^+. and [(C₆H₅)₂CH₃P]^+. ions respectively, resulting from [M]^+. by migration of C₆H₅. Rearrangement of [M]^+. to a 4-membered P-S ring system prior to fragmentation is suggested.     

Studies on the series of azoles and azines. 65. Mass spectra of 5-arylidene-, 5-ethoxycarbonylmethylene-hydantoins and their derivatives

The mass spectra of 5-m- and p-substituted benzylidenehydantoins, their thio analogs and 5-carbethoxymethylenehydantoins with a substituent at the -carbon atom of the side chain were studied. The fragmentation of the molecular ions of 5-arylidenehydantoins proceeds in one direction, splitting of the X=C-NR-C=O fragment, irrespective of the substituent in the benzene ring. The peak intensity of the fragmentary ions formed from the molecular ions is linearly dependent on the -constants of the substituent. The direction of the fragmentation of 5-ethoxycarbonylmethylenehydantoins markedly depends on the substituent at the -carbon atom in the side chain that determines the stability of the hydantoin ring and the carboethoxyl group. The fragmentation of these compounds under electron impact proceeds by five paths, related to splitting of fragments O=C₍₂₎NCH₍₄₎=O, C₂H₄, C₂H₅O, C₂H₅OH, and COOC₂H₅.See [1] for Communication 64.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 625–631, May, 1988.     

The electronic structure and reactivity of small ring compounds—VII : The CMR spectra of 1-cyanobicyclo[1.1.0]butane

The 25·2 MHz CMR (FFT) spectra of 1-cyanobicyclo [1.1.0]butane are reported both with and without hydrogen decoupling. Chemical shifts are discussed in terms of dipolar resonance contributions to the ground state and the unsaturated nature of the bicyclobutane ring. The C-H coupling constants, including directly bonded and long range interactions, are reported. It is suggested that the large long range H_x′-C₂ coupling constant is a result of a favorable interaction between the H_x′-C₄ bond and C₂ bond and C₂ and that the H₃-cyano carbon coupling constant results from a 0° dihedral angle and to a small extent, if at all, from a favorable geometry. The C₁-C₂ (22 Hz) and C₁-C₃ (16 Hz) ¹³C-¹³C coupling constants are presented, compared with the calculated values, and discussed in terms of hybridization. The possibility of a negative value for the C₁-C₃ coupling constant is also considered. It is pointed out that using coupling constant-hybridization relationships and extrapolating from several known to an unknown hybridization around a carbon atom can, in many cases, lead to a sizeable error in calculated hybridization.     

Peculiarities of dissociative ionization of alkylcyclopentadienyl nitrosyl π-complexes of nickel

The decomposition of alkylcyclopentadienyl nitrosyl -complexes of nickel, (C₅H₄R)(NO)Ni (R=H, Et,i-Pr, CH₂Ph), under the action of electron impact has been studied. The nature of the nitrosyl ligand has been shown to be the factor determining the main fragmentation pathway which involves the abstraction of an NO molecule. The effect of the nature of the ligand on the ability of the molecular ion (C₅H₄R)LNi⁺ (L=C₅H₄R, C₅H₅, C₃H₅, NO) to rearrange with hydrogen atom migration from one ligand to another has been considered. The structure of the alkyl group R determines a competing fragmentation pathway involving cleavage of the -C-C bond with respect to the cyclopentadienyl ring in the substituent.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1985–1988, November, 1993.     

Mass spectrometric study of 9-substituted 10-sila-2-azaanthracenes

The dissociative ionization of 10 derivatives of 10-sila-2-azaanthracene, containing cyanoethyl (I–III), aminopropyl (IV), amino (V, VI), and amide (VII–X) groups at the C₍₉₎ atom, was investigated. It was shown that for all the compounds the general direction of decomposition is elimination of substituents from the silicon and carbon C₍₉₎ atoms. The stability of the compounds to electron impact is determined chiefly by the nature of the substituent at the C₍₉₎ atoms and depends weakly on the type of substituent at the silicon atom. In the case of amino-derivatives V–X, fragmentation of the molecular ions is determined by the method of localization of the positive charge in the molecular ion. This determines the occurrence of specific decompositions, which permits reliable identification of the compounds studied according to their mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1071–1076, August, 1984.     

Cyclopropane Adsorption on Zeolites Studied by IR Spectroscopy: II. Adsorption and Conversion of Cyclopropane on Na- and Ca-Exchanged Zeolite Y

The adsorption and isomerization of cyclopropane on the calcium- and sodium-exchanged zeolite Y are studied by IR spectroscopy. Cyclopropane is adsorbed on CaY in two different forms. Weaker adsorption is related to residual sodium ions, which were not completely removed from the zeolite by ion exchange. This form can be removed from the surface after evacuation of the samples at room temperature. Stronger adsorption is attributed to the Ca ions. It is stable up to 100°C. The corresponding diffuse-reflectance spectrum indicates the C _2v symmetry of the cyclopropane complex with Ca ions. At 200°C cyclopropane adsorbed on the calcium-exchanged zeolite converts to propylene. On the sodium-exchanged zeolite, this reaction only occurs at 400°C. The reaction coordinate of cyclopropane isomerization on CaY is related to the simultaneous cleavage of the C–C bond in the cyclopropane ring and hydrogen atom transfer from one of the CH₂ fragments to another. The reaction coordinate corresponds to a combination of the stretching vibration of the C–C bond with the fan vibration of the CH₂ group and the stretching vibration of the CH bond. These composite vibrations result in the strong polarization of the C–C and C–H bonds and, hence, exhibit anomalously high molar absorption coefficients in the IR spectrum.     

Cyclization of nitriles 41. Reaction of arylmethylenemalononitriles with malononitrile; crystal structure of 1-amino-3.5-diphenyl-2,4,4,6,6-pentacyano-1-Cyclohexene

1-Amino-3,5-diaryl-2,4,4,6,6-pentacyano-1-cyclohexenes are prepared by reaction of arylmethylenemalononitriles with malononitrile. The cyclohexene ring of (IVa) has a distorted N₂-C¹=C²-C⁷=N¹ fragment. Steric effects in (IVa) cause a substantial increase in C⁶-C¹ and C³-C⁴ bond length to 1.546(4) and 1.570(4) Å, respectively.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2771–2775, December, 1989.     

Mass spectrometry of biologically active substances

The mass spectra of 2- and 4-iminobarbituric acid derivatives were studied in relation to the mass spectra of their oxygen analogs. It is shown that the pathways of fragmentation of the investigated compounds depend on the type of substituent attached to the C₅ atom, the position of the imino and oxo groups in the ring, and the specific mass-spectral properties. The fragmentation was studied by means of low-voltage mass spectrometry and deuterium labeling.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 813–817, June, 1978.     

Reaction of dihalocarbenes with some cycloolefins,derivatives of cyclohexene,cycloheptene, and cyclooctene

Conclusions Dichlorocarbene and dibromocarbene were added to a number of cycloolefins with a ring size of C₆-C₈, and the relative reactivity of the latter toward these electrophilic reagents was determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2045–2051, September, 1973.The authors express their gratitude to I. P. Yakovlev for assistance in taking and interpreting the IE spectra.     

Reactions of 2,3-Dichloro- and 2,3,5-Trichloro-4,4-ethylenedioxy-2-cyclopentenones with Some O-, S-, and N-Nucleophiles

2,3-Dichloro- and 2,3,5-trichloro-4,4-ethylenedioxy-2-cyclopentenones react with allyl and benzyl alcoholates and thiolates and benzylamine to give products resulting from Ad_NE substitution of the 3-chlorine atom, [1,3]-sigmatropic rearrangement, and cleavage of the C¹-C² bond.