1H- und 13C-NMR.-Spektren von 6-(p-X-Phenyl)fulvenen. Kurzmitteilung

¹H- and ¹³C-NMR.-spectra of 6-(p-X-phenyl)fulvenes The ¹H- and ¹³C-NMR.-spectra of a series of 6-(p-X-phenyl)fulvenes 3 , measured at 9.39 T (93.9 kgauss), have been analyzed. In these compounds, electronic effects due to the substituent X clearly exert changes in chemical shifts as well as in coupling constants in the 5-membered ring. Small changes in bond length are observed by comparison of the vicinal ¹H, ¹H-coupling constants, whereas changes in charge densities linearly influence the chemical shifts of C(5), C(2) and C(3).     

13C-NMR.-Spektren von 3H-Benz[cd]azulen-3-onen

¹³C-NMR. Spectra of 3H-benz[cd]azulenc-3-ones ¹³C-NMR. Spectra of 7,9-dimethyl-3H-benz[cd]azulenc-3-one ( 2 ) and 7,9-dimethyl-4,5-dihydro-3H-benz[cd]azulene-3-one ( 7 ) in CDCl³ and CF₃CO₂D are reported. The assignment of signals was achieved with the aid of selective proton decoupling, non-decoupled spectra and comparison with spectra of simple azulene-derivatives. The major localization of positive charge in the cationic 3-hydroxybenz-[cd]azulenium system was found in the six- and seven-membered ring, which suggests in accordance with calculated π-electron densities the structure of a benztropylium ion rather than a bridged azulenium ion.     

Tieftemperatur 13C-NMR.-Spektren von 13C-und 6Li-markierten Chlor-, Brom- und Jod-Lithium-Carbenoiden. Vorläufige Mitteilung

Low Temperature ¹³C-NMR. Spectra of ¹³C- and ⁶Li-Labelled Chloro-, Bromo-, and Iodo-lithiumcarbenoids The ¹³C-NMR. spectra of tetrahydrofuran solutions of 16 chloro-, bromo-, and iodo-⁶lithio- and -⁷lithio-carbenoids with ¹³C-labelled methane, ethane, ethylene, and cyclopropane C-skeletons have been measured at temperatures around ? 100° (for examples see Fig. 1 and 2). Invariably, the exchange of hydrogen or halogen by lithium causes deshielding (Δδ, see Table 1) of the ¹³C-signal by up to 289 and 434 ppm, respectively, and decrease of ¹J (¹H, ¹³C) and ¹J(¹³C,¹³C) couplings (see Table 2) with the C-atom of up to 104 and 30 Hz, respectively. The ¹J(⁶Li, ¹³C) and ¹J(⁷Li, ¹³C) coupling of ca. 17 and 45 Hz, respectively, obtained in ten cases (Table 1) is independant of the substitution pattern of the C-skeleton and of the particular halogen atom.     

Synthese und NMR.-Spektren von neuartigen Lanthanoid-Kobalt-Sandwichkomplexen

Synthesis and NMR. Spectra of Novel Lanthanide-Cobalt Sandwich Compounds The reaction of [(C₅H₅)Co{P(O)(OR)₂}₂{P(OH)(OR)₂}] ( 3 , R = CH₃, C₂H₅) with lanthanide(III) compounds yields the cationic trinuclear complexes [{(C₅H₅)Co[P(O)(OR)₂]₃}₂Ln]^⊕X^? ( 2 , R = CH₃, C₂H₅; Ln = La, Eu, Pr; X = BF₄, BPh₄). According to thermogravimetric and NMR. studies these compounds do not contain additional coordinated water molecules. It is therefore supposed that the central lanthanide ion has a regular sixfold coordination of phosphoryl ligands. The ³¹P- and ¹H-NMR. spectra of 2 (R = CH₃; Ln = La, Eu, Pr) and 3 are discussed. It can be shown that the Fermi contact shift as well as the coordination shift make significant contributions to the observed lanthanide induced shift of the cyclopentadienyl signal.The dominating influence of the Fermi contact interaction on the ³¹P chemical shift is in accord with theoretical considerations and comparable experimental values. The temperature dependence of the proton chemical shifts of 2 (R = CH₃; Ln = Eu) is also discussed.     

13C-NMR.-Spektren N-acylierter Indoline. Einfluss der Orientierung der Carbonylgruppe auf die chemische Verschiebung

¹³C-NMR. spectra of N-acylated indolines. Effect of the orientation of the carbonyl group on the chemical shift Large downfield shifts are observed in the ¹³C-NMR. spectra of indolines and related compounds induced by electric field effects of carbonyl and oxime groups.     

Strukturbestimmung von O-Methylazafrinmethylester durch 13C-NMR.-Spektroskopie

Structure Determination of Azafrin Methyl Ester 5-O-Monomethyl Ether by ¹³C-NMR.-Specta. The structure of the monomethyl ether ( 2 ) of azafrin methyl ester ( 1 ) was determined by a partial analysis of the ¹³C-NMR.-spectra. Assignments of quaternary carbon atoms and methyl groups in the cyclohexane ring were achieved using vicinal ¹³C-, ¹H-spin coupling. Substituent effects on methyl and methylene carbon atoms in 2 are discussed with respect to the conformation of the methoxy group. The spectra prove C(5)? OH as the site of methylation. Therefore C(5)? OH is less hindered than C(6)? OH.     

Fulvene,VII. Analyse der 13C- und 1H-NMR.-Spektren

Carbon-13 and proton NMR. spectra of pentafulvene and of a series of 6-substituted fulvenes have been analysed and assigned by homo- and heteronuclear double resonance and with the aid of iterative computation. ¹³C and ¹H chemical shifts are interpreted in terms of substituent effects and compared with π-electron charges calculated for the unsubstituted fulvene. From ¹³C shifts a 10 percent contribution of dipolar structures to the electronic configuration of fulvene may be estimated. All long-range proton-proton coupling constants including relative signs and some proton-carbon couplings in the fulvene spin system have been determined and assigned.     

1H- und 13C-NMR.-Spektroskopie der Nonadride

¹H- and ¹³C-NMR. Spectroscopy of the Nonadrides The ¹H- and ¹³C-NMR. spectra of the nonadrides glaucanic acid ( 1 ), glauconic acid ( 2 ), heveadride ( 3 ), byssochlamic acid ( 4 ), scytalidin ( 5 ), rubratoxin A ( 6 ), and rubratoxin B ( 7 ) have been measured. Partial decoupling experiments permitted assignment of the majority of the signals.     

Über die Temperaturabhängigkeit der 13C-NMR.-Spektren von Tetracarbonyl (η-(Z)-cycloocten)eisen und (Z)-cycloocten

On the Temperature Dependence of the ¹³C-NMR.-Spectra of Tetracarbonyl (η-( Z )-cyclooctene)iron and of ( Z )-Cyclooctene Reaction of (Z)-cyclooctene (1) with Fe₂(CO)₉ in pentane at 0° yielded tetracarbonyl(η-(Z)-cyclooctene)iron (2) as a yellow oil which can be stored over a longer period only at ?78°. It is shown that the title compounds ( 1 and 2 , respectively) are fluxional. The activation parameters for the conformational C-atom site exchange of (Z)-cyclooctene (1) and tetracarbonyl (η-(Z)-cyclooctene)iron (2) (in CCl₂F₂) have been determined between 113 K and 151 K for 1 and between 151 K and 205 K for 2 , respectively, by a complete line shape analysis of the temperature dependent proton noise-decoupled ¹³C-NMR. signals of the olefinic C-atom. The kinetic data and activation parameters are given in Tables 1 and 2.     

Die Auswertung von γ-Spektren mit Programmen

Modern activation analysis requires the application of efficient data processing for the evaluation of theγ-spectra of samples containing several radionuclides, especially if preceding radiochemical separations are to be largely or completely eliminated. The essential aspects of two programs for quantitative determinations and qualitative identifications are described. These programs are based on the least squares analysis of the total spectrum and the search, arrangement and processing of the photopeaks. With respect to their details the programs are adapted for application on the computer IBM-360/75.     

13C-NMR. Spectra of Pteridines

¹³C-NMR. spectra of pterin, xanthopterin, isoxanthopterin, leucopterin, lumazine and of the model compounds isocytosine and desamino-isocytosine have been measured as anions and cations in 1 M NaOD, CF₃COOH, H₂SO₄ and FSO₃H solutions. The spectra were analysed by means of heteronuclear double resonance, with the aid of non-decoupled spectra, and by spectral comparison. The results are interpreted in terms of the ionisation state of the pteridines in the four solvents and are compared with those obtained from ¹H-NMR. spectroscopy.     

13C-NMR.-Spektroskopie von Organolithiumverbindungen bei tiefen Temperaturen. Strukturinformation aus der 13C, 6Li-Kopplung

Low-Temperature ¹³C-NMR. Spectroscopy of Organolithium Derivatives. - ¹³C, ⁶Li-Coupling, a Powerful Structural Information The ¹³C-NMR. spectra of thirteen lithiated hydrocarbons ( 1c–13c . Table 2) and of eighteen a-halo-lithium carbenoids ( 14c–31c , Table 3) have been recorded in donor solvent (R₂O, R₃N) mixtures at temperatures down to ?150°. The organolithium species were generated from singly or doubly ¹³C-labelled precursors by H/⁶Li- or Br/⁶-exchange. - ¹³C, ⁶Li-Coupling was observed of all species but those which supposedly contain contact ion pair C,Li-bonds (benzylic and acetylenic derivatives). The multiplicities of the signals are correlated with the degree of aggregation in solution: the triplets of the halocarbenoids must arise from monomers or heteroatom-bridged oligomers, the quintuplets of butyl-, cyclopropyl-, bycyclo[1.1.0]butyl-, vinyl-, and phenyllithium from dimers with planar arrangement of two Li- and two C-atoms, as known from crystal structures (Scheme 3). All ¹³C, ⁶Li-couplings are temperature-dependent, dynamic processes cause them to disappear above ca. ?70° (Fig. 1–4). - Types of organolithium compounds are categorized according to the change of chemical shift δΔ (H, Li) upon H/Li-substitution, according to the ¹³C, ⁶Li-coupling constants ranging from 0 to 17 Hz, and according to the multiplicities which indicate the aggregation: type A are Li-derivatives of alkanes and cycloalkanes, type B are s?-bonded vinyl, aryl, and alinyl derivatives, type C are a-heterosubstituted (RS, hetero=halogen) organolithium compounds, and type D are π-bonded allylic and benzylic systems (Table 5). The C,Li-distances in the crystal structures of representatives of all four classes are within the small range of 2.18–2.28 Å (cf. Scheme 3). - Some surprising observations and their interpretations and consequences are: (a) butyllithium solutions in THF, THF/TMEDA, and dimethyl ether contain increasing amounts of dimer upon cooling, the equilibrium (tetramer · 4 THF)+4 THF ? 2 (dimer · 4 THF) being shifted to the right (Fig. 1 and Scheme 4); thus, more of a different species is present at low temperatures, with the accompanying changes in reactivity; (b) mixed higher aggregates are formed upon addition of butyllithium to bicyclobutyllithium; these are broken up to dimers upon addition of TMEDA (Tetramethylethylene-diamine) (Fig. 2 and Scheme 5); (c) the solid state, the calculated gas-phase and the solution species of phenyllithium all have dimeric structures, and so do vinyl and cyclopropyl lithium derivatives; the ¹³C-deshielding observed upon replacement of H by Li on sp²- and sp-C-atoms is related to a polarization of the π-electrons (Table 3, Fig. 3 and Scheme 6); (d) the spectra of halo-lithium carbenoids show three striking features as compared to the C,H-compound: deshielding of up to 280 ppm (Table 3), strong decrease of the coupling constant with ¹H- and ¹³C-nuclei attached to the carbenoid C-atom (Table 4), and a structure-independant, almost constant, large ¹³C, ⁶Li-coupling constant of 17 Hz (Table 3); as shown in Scheme 7, these effects might be the consequence of a reduced degree of hybridization of the carbenoid C-atom. - The preparation of the labelled compounds and the generation of solutions of the organolithium compounds for NMR. measurements are described in full detail.     

Direkte und indirekte metallierung von endo-dicylopentadien. Sn- und C-NMR studie stannylierter folgeprodukte

endo-Dicyclopentadiene (1) can be metalated by use of simple procedures with good overall yields. The attack occurs at the various vinyl, rather than at the allyl, positions of 1 as was confirmed by trapping the carbanions with Me₃SnCl. When t-BuLi/TMEDA are used, the 8- and 9-stannyl derivatives (3 and 4) are formed, whereas an excess of n-BuLi/t-BuOK leads to doubly stannylated derivatives with Me₃Sn groups in position 4/8 (6), 4/9 (7), and 3/9 (8) in addition to 3 and 4. Furthermore the latter reaction yields 5,5-bis(trimethylstannyl)cyclopentadiene (5). With stoichiometric amounts of n-BuLi/t-BuOK the formation of 3 and 4 predominates over that of 5–8. 5 is obtained from 1 after deprotonation at the allyl position, followed by an extremely fast retro-Diels-Alder reaction and then by further deprotonation. This follows from two experiments: (1) exo- and endo-5-trimethylstannyl-endo-dicyclopentadiene (11 and 12) which are synthesized from 1 in three steps give cyclopentadienyllithium and 1 when treated with methyllithium at −78°C; (2) cyclopentadiene reacts with an excess of n-BuLi/t-BuOK and Me₃SnCl to give 5. When 12 is heated syn-10-trimethylstannyl-endo-dicyclopentadiene (13) is obtained. The eight stannyl derivatives of 1 are identified mainly from the following NMR parameters: δ(¹¹⁹Sn), δ(¹³C), δ(¹H), ⁿJ(^119/117Sn---¹³C), and ⁶J(¹¹⁹Sn---^119/117Sn). The ¹³C NMR satellite spectrum of 1 yields the isotope shifts ¹Δ¹³(i(¹³C(j)) and ¹J(¹³C---¹³C). The latter lead to the revision of earlier signal assignments.     

Mathematische Auswertung von Mehrkomponenten-γ-Spektren

The use of a computer is advantageous for the qualitative and quantitative evaluation of multicomponent γ-spectra. The fundamentals of this method are described, the required systems of equations are explained, and the practical application is demonstrated with an example of a mixture of radionuclides.     

13C-NMR. Analysis of the Roxburghines

The ¹³C shifts of the alkaloids roxburghine B, C, D and E are determined. They confirm the following configurations for the last three bases: C(18α)-normal, C(18α)-pseudo and C(18β)-pseudo, respectively. Roxburghine B is shown to be a C(18β)-epi-allo isomer.     

Chemie der pleuromutiline-VI : Vergleichende untersuchung der 13C-NMR spektren des tricyclischen diterpens mutilin und einer reihe von mutilinderivaten

The ¹³C NMR spectra of the diterpenes pleuromutilin,¹ mutilin,¹ and related compounds are discussed in detail. The complete assignment of the signals to the individual C-atoms of the tricyclic system is based on comparisons of spectra as well as increment calculations. The syntheses of the investigated compounds are described, if they were not mentioned in earlier papers.     

Gitterschwingungsspektren 13. Mitt. Normalkoordinatenanalyse und Kraftkonstantenrechnungen von Chromthiospinellen

Ohne Zusammenfassung     

13C-NMR-spektren und dynamisches verhalten von olefin- sonitril-eisendicarbonyl-komplexen.

The ¹³C NMR spectra of the isonitrile complexes olen fe(CO)₂CNR (R = Me, EMe₃; E = Si, Ge, Sn) with butadiene, penta- 1,3-diene, cyclohexa-1,3-diene, 2,3-dimethylbutadiene, cyclohepta-1,3-diene as olefiinic ligands indicate the fluctional behavior of these compounds in solution. At low temperature there is a conformative preference in all cases so that one CO group occupies the apical position of a square pyramid whereas the isonitrile ligand together with a CO and the olefin part are in the basal positions. Depending on te various olefin ligands and the CNR groups the pseudorotation process is dicussed on the basis of /gDG/DG values for the CO/CNR ligand exchange.