Synthesis and conformational behaviour of tetra-anthranilides

The tetra-anthranilide derivatives ($\text{5}$)–($\text{7}$) have been synthesised. X-Ray crystallography shows that $\text{N}$,$\text{N}$′,$\text{N}$″-trimethyltetra-anthranilide ($\text{5}$) adopts a conformation with three $\text{trans}$ - and one $\text{cis}$-amide linkages in the solid state. Dynamic ¹H n.m.r. spectroscopy indicates that $\text{N}$-benzyl-$\text{N}$′,$\text{N}$″,$\text{N}$′″-trimethyltetra-anthranilide ($\text{7}$) exists as an interconverting ternary mixture of chiral non-planar conformational diastereoisomers in solution.     

Trimethymetall-urotropinaddukte des aluminiums,galliums, indiums und thalliums

Reactions of urotropine (C₆H₁₂N₄) with trimethylmetal derivatives of Al, Ga, In und Tl in various ($\text{1}\text{1}$$\text{1}\text{4}$) molar ratios lead to stable and monomeric $\text{1}\text{1}$, $\text{1}\text{2}$ or $\text{1}\text{3}$ adducts in good yields, but no $\text{1}\text{4}$ addition product could be isolated. The vibrational spectra (IR and Raman) of all compounds are recorded and partly assigned. Some characteristic frequencies of the C₆N₄-skeletons clearly show the symmetry changes in the series of the $\text{1}\text{1}$ → $\text{1}\text{2}$ → $\text{1}\text{3}$ adducts (C_3ν → C_2ν → C_3ν). The X-ray structure determinations of C₆H₁₂N₄·.GaMe₃ (MeCH₃) and C₆H₁₂N₄·.2GaMe₃, are in good agreement with the vibrational spectra. Both compounds crystallize in monoclinic space groups (P2₁ and C2/c). The GaN distances are around 214 pm, and the values for the C₆N₄-skeletons are not significantly different from those for free urotropine.     

Alkylations of bis(phenylthio)acetals

Bis(phenylthio)acetals can be lithiated with n-butylithium-$\text{N}$,$\text{N}$,$\text{N}$′,$\text{N}$′-tetramethylethylenediamine complex in hexane and consequently alkylated.     

Synthesis and conformational behaviour of tri-3-methyltrianthranilides. A new example of spontaneous resolution and inclusion compound formation on crystallisation

The tri-3-methyltrianthranilide derivatives ($\text{7}$)–($\text{9}$) have been synthesised. Dynamic ¹H n.m.r. spectroscopy indicates that the $\text{N}$,$\text{N}$′,$\text{N}$″-trimethyl derivative ($\text{8}$) exists in solution as slowly ring inverting ($\text{16}$ ? $\text{16}$*) enantiomeric helical conformations. X-Ray crystallography shows that the $\text{N}$,$\text{N}$′-dimethyl-$\text{N}$″-benzyl derivative ($\text{9}$) undergoes spontaneous resolution when it crystallises as a 1:1 adduct from toluene. The host molecules adopt a helical conformation (Figure 1) within a lattice structure that contains chiral channels (Figure 2) occupied by guest solvent molecules.     

Microwave-optical double resonance in molecular ions. Co+

Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for ¹²C¹⁶O⁺. With the optical excitation of fluorescence from the R₁ ($\text{1}\text{2}$) line of the (0,0) band of the A²Π_{$\text{3}\text{2}$} ← X²∑ transition of 20350.6 cm^?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = $\text{3}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ and the N = 1, J = $\text{1}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ transitions.     

Reaktionen an komplexgebundenen Liganden. XXXII.: Synthese und eigenschaften von heteronuklearen mangan-chrom-komplexen mit distickstoff- diazen- und hydrazin-brükenliganden

Synthesis and properties of C₅H₅(CO)₂Mn-N₂H₄-Cr(CC)₅$\text{(1)}$, C₅H₅(CO)₂Mn-N₂H₂-Cr(CO)₅$\text{(2)}$ and C₅H₅(CO)₂Mn-N₂-Cr(CO)₅$\text{(3)}$ are reported. $\text{(1)}$, $\text{(2)}$ and $\text{(3)}$ constitute the first series of heteronuclear complexes in which N₂, N₂H₂ and N₂H₄ are bound to identical metal centers. $\text{(1)}$ and $\text{(3)}$ are obtained by reacting C₅H₅Mn(CO)₂N₂H₄ respectively with Cr(CO)₅THF, $\text{(2)}$ by oxidation of $\text{(1)}$. $\text{(2)}$ disproportionates by addition of base yielding $\text{(3)}$ and H₂. The IR Spectrum of $\text{(2)}$ allows the assignment of five normal vibrations of the diazene ligand; in the IR spectrum of the deuterated analogue all six normal vibrations can be assigned. The ¹H-NMR spectrum of $\text{(2)}$ yields the coupling constant of protons on NN double bonds for the first time; the value of ³J_HH  23,5 Hz points to a trans structure of $\text{(2)}$.     

Asymmetrical nonbridgehead nitrogen—30 geminal systems—21: The influence of vicinal n — σ* interaction on the pyramidal stability of tricoordinated nitrogen atom in the geminal system

The vicinal n - σ^* interaction stabilizes the pyramidal state of the nitrogen geminal system

where X and Y are electronegative substituents with high-lying levels of nonbonding n orbitals. A approximate value for the energy of n - σ^* stabilization of pyramidal state in $\text{N}$,$\text{N}$-dialkoxyamines, equal to ～5.7 kcal/mol, has been found by comparing the average experimental value of the inversion barrier for these compounds with the one calculated according to the additive scheme. The influence of the vicinal n - σ^* interaction on the structural peculiarities of $\text{N}$-alkoxyisoxazolidines manifests itself in the conformations with the greatest overlapping of n and σ^* orbitals being predominantly populated and in a change in NO bond lengths and valence angles. The combination of a ligand having the highest-lying level of n orbital with a ligand, which forms the σ bond with a N atom, having the lowest-lying antibonding level results in the dissociation of a nitrogen geminal system into an ionic planar form of the

type. From this is inferred the dual nature of the influence exerted by the vicinal n - σ^* interaction upon the inversion barrier of the

geminal system.     

Über reaktionen mit aluminiumalkylen: XVII. Spektroskopische untersuchungen von komplexen aus butanoliden und äthylaluminium-verbindungen

Three different types of butanolide complexes with Et_nAlCl_3?n in the molar ratios $\text{1}\text{1}$ and $\text{1}\text{2}$ have been investigated by IR with ^1M NMR spectroscopy. The butanolides form $\text{1}\text{1}$ and $\text{1}\text{2}$ complexes with ethylaluminium halides, but with triethylaluminium only $\text{1}\text{1}$ complexes are formed. The complexes are intermediates in the cleavage of butanolides.     

Fluorescence lifetime studies of no a 2Σ+(ν = 5, N = 9), B2Π32(ν = 8, J = 8.5), CwΠ32(ν = 1, J = 8.5), D2Σ+ (ν = 0, N = 5) and D2Σ+(ν = 1, N = 9)

Fluorescence decay profiles of NO excited levels slightly above the dissociation limit have been measured by a single-photon counting technique with nanosecond pulse excitation using an iodine flash lamp. Three iodine atomic lines in the vicinity of 180 nm are found to bring NO molecules into the levels A²Σ⁺(ν = 5, N = 9), B²²Π_{$\text{3}\text{2}$}(ν = 8, J = 8.5), C²Π_{$\text{3}\text{2}$}(ν = 1, J = 8.5), D²Σ⁺(ν = 0, N = 5) and D²Σ⁺(ν = 1, N = 9). Extrapolated zero-pressure lifetimes for single rotational levels are obtained, except for the C state where only a lifetime of ⩽0.4 ns was obtained. Self-quenching rate constants are also determined under higher-pressure conditions. Helium was found to quench the NO A²Σ⁺(ν′ = 5) fluorescence very efficiently.     

Action of tert-butyl azidoformate on the conjugate bases of 1,2,3,4-tetrahydro-9H-carbazole and other indole derivatives

tert-Butyl azidoformate ($\text{2}$) reacts with the conjugate bases of $\text{3a}$, $\text{7a}$, $\text{9}$ (R¹ = R² = CH₃), and $\text{9}$ (R¹ = CH₃, R² = H) to give products [$\text{4}$, $\text{8}$, $\text{12}$, and $\text{14}$, respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives.     

Oxidation of N-hydroxyazetidines: A novel synthesis of N-acetoxy β-Lactams and four-membered cyclic nitrones

The N-hydroxyazetidines $\text{2}$ and $\text{3}$ are prepared startinfrom 2,3-dihydroazete 1-oxides ($\text{1a}$ and $\text{1b}$0 by reduction with sodium borohydride and by reaction with a nucleophile, respectively. The N-thydroxyazetidines $\text{2}$ and $\text{3}$ can be oxidized with mercury (II) oxide to the corresponding nitrones $\text{1}$; oxidation of the N-hydroxyazetidine $\text{2a}$ (unsubstituted at C-4) with $\text{two}$ equivalent of lead tetraacetate tyields the N-tacetoxy β-lactam $\text{4}$.     

Fractal structure of three-dimensional Witten—Sander clusters

Five large (25 000 particle) three-dimensional Witten—Sander clusters have been generated, and geometric relationships characterizing this structure have been examined. The quantities measured include the dependence of the radius of gyration. (r²)^{$\text{1}\text{2}$}, and (r⁴)^{$\text{1}\text{4}$} on cluster size N, the mass M(r) contained within a distance r from the center mass, the dependence of the areas of projections of the clusters onto a plane of cluster size N, the density—density correlation function and the distribution of particles (occupied lattice sites) in cubes of side λ as a function of λ. Although uncertainties are quite large, our results are consistent with the concept hat the geometric scaling properties of three-dimensional Witten—Sander clusters can be described in terms of a single effective dimensionality D with a value of = 2.45. Additional results are also presented for two-dimensional Witten—Sander clusters which indicate a single effective dimensionality with a value of = 5/3.     

Synthesis of chiral tripeptides by asymmetric hydrogenation of dehydrotripeptides. Remarkable effects of N-protecting groups on stereoselectivity and reactivity

Dehydrotripeptides, X-$\text{C}\text{*}$CH(Rⁱ)-ΔPhe-$\text{C}\text{*}$CH(R^k)COOMe ($\text{3}$: X = ^tBOC-NH,CBZ-NH, CF₃CONH and N₃), were employed for the asymmetric hydrogenation catalyzed by chiral rhodium complexes and it was found that ^tBOC-$\text{3}$ brought about by far the best results. Stereoselective dideuteration of a ^tBOC-$\text{3}$ was successfully performed.     

Synthèse et structure cristalline d'un nouvel oxyde mixte FeV2O6H0.5 relation avec la structure type diaspore

Single crystals of a new compound, FeV₂O₆H_0.5, have been obtained by hydrothermal synthesis at 650°C and 2 kbar. An electron microprobe analysis indicated that the chemical formula is FeV₂O₆. This compound has an orthorhombic symmetry, space group P2₁2₁2₁ with Z = 4. The unit cell dimensions are

$\text{a = 4.891}\text{A}\text{?}\text{, b = 9.553}\text{A}\text{?}\text{, c = 8.786}\text{A}\text{?}$

These parameters are related to a′, b′, c′ of the diaspore-type VO₂ by the relations: $\text{a ? a′, b ? b′, c ? 3c′}$. The structure, based on single crystal data, has been determined from Patterson and Fourier syntheses. A structural refinement gave a final R-factor of 2.4%. The new structure can be deduced from that of the diaspore-type VO₂, by displacement of one third of the cations from an octahedral site to an adjacent unoccupied tetrahedral site, which is located in a channel parallel to the c axis. The calculation of the cation and oxygen valences indicated that some O^2? were in fact OH^?. This conjecture was supported by thermogravimetric analysis. The chemical formula was indeed Fe³⁺₂V³⁺V⁴⁺V⁵⁺₂O₁₁(OH). Some intensities of the powder diffraction lines changed strongly when the preparation temperature was reduced from 650°C to 300°C. This was explained by an increase of the hydrogen ratio in the formula FeV₂O₆H_x, which implies a structural change. The different phases FeV₂O₆H_x can be considered as solid solutions between two extreme phases with different structure: one with the present one and the other with a diaspore-type structure.     

Struktur und Bindung in Übergangsmetall-Fluoriden MIIMeIVF6: Neutronenbeugungs-Strukturuntersuchungen an CaSnF6, FeZrF6, und CrZrF6

Compounds M^IIMe^IVF₆ requently undergo phase transitions from the cubic ordered ReO₃ to the trigonal LiSbF₆ structure when lowering the temperature. In case of a strongly Jahn-Teller unstable cation in the M^II position additional phases may occur. Results of powder neutron-diffraction studies on CaSnF₆, FeZrF₆, and CrZrF₆ at different temperatures are reported. The high-temperature phases have the space group Fm3m; the F^? ligands are either statistically displaced from the M^IIMe^IV directions or undergo a strong thermal motion perpendicular to these directions ($\text{?M}{}^{\mathrm{<mtext>II</mtext>}}\text{}\text{FMe}{}^{\mathrm{IV}}$: 165–180°). The thermal ellipsoids of the CrF bonds are strongly indicative of a dynamical Jahn-Teller effect in addition. In the low-temperature phases of CaSnF₆ and FeZrF₆ (space group $\text{R}\text{3}$) the $\text{?M}{}^{\mathrm{<mtext>II</mtext>}}\text{}\text{FMe}{}^{\mathrm{IV}}$ is more distinctly bent (?155–160°). CrZrF₆ undergoes two reversible phase transitions, which are determined to occur at 415 ± 5 K (cubic → tetragonal, dynamic to static Jahn-Teller distortion of CrF₆ octahedra and 150 ± 10 K (tetragonal → (pseudo)monoclinic).     

The benzoylation of uracil and thymine

Uracil and thymine react with benzoyl chloride in acetonitrile-pyridine solution at room temperature to give first their 1-$\text{N}$-benzoyl (2b and 3b) and then their 1-$\text{N}$, 3-$\text{N}$-dibenzoyl derivatives (4a and 4b, respectively); the latter compounds are converted into the corresponding 3-$\text{N}$-benzoyl derivatives (5a and 6a) under mild conditions of basic hydrolysis.     

Concerning the “novel intramolecular hydrogen bond to a trans-syn,s-cis formazan system”: solution isomers of 3-carboxymethylthio- and 3-methoxy-carbonyl-1,5-diphenylformazan

Spectroscopic studies of the [1,5-¹⁵N₂]-labelled title compounds demonstrate the presence of the yellow trans-anti,s-trans ($\text{1}$) and the red trans-syn,s-cis ($\text{2}$) isomers in solution. There is no experimental evidence supporting the postulated novel hydrogen bridge $\text{5}$.     

Photoreactions of 2,3-diazatetracyclo[5.3.1.04,11.06,8]undeca-2,9 dienes ; the retro-1,3-dipolar cycloadditions and the nitrogen extrusion reactions

The photochemical reactions of tetracyclic azo compounds ($\text{1a–b}$) giving $\text{5a–b}$ and $\text{8a–b}$via diazoethane derivatives ($\text{6a–b}$) were investigated in addition to the nitrogen extrusion reactions leading to tetracyclo[4.3.0.0^2,9.05,7nonenes ($\text{4a–b}$).     

Preferential energy transfer from N2(A) to specific energy levels of Cu atoms

Emission spectra resulting from reaction of “clean” N₂(A³ Σ_u⁺) with copper atoms were studied using a flowing afterglow apparatus. The population distribution of the Cu states was calculated from the spectrum; it indicates that Cu atoms are excited by nearly resonant energy transfer processes. N₂(A,v') + Cu(²S_{$\text{1}\text{2}$}) → N₂(X, v) + Cu^* , and that the transfer is most efficient for N₂(A,v') → N₂(X,v) transitions with large Franck-Condon factors. The preferential energy transfer results in population inversion between some of the Cu states.     

ESR- und ENDOR-untersuchungen paramagnetischer zinnkomplexe und strukturanalyse von 3,5-di-t-butyl-1,2-phenylendioxi-bis(o-trifluormethyl-phenyl)-(methanol)zinn(IV)

Triorganyltin compounds react with catechols in organic solvents in the presence of atmospheric oxygen to give at first paramagnetic complexes. The ESR and ENDOR spectra show ¹H, ¹⁹F, ¹¹⁷Sn and ¹¹⁹Sn splittings. The hyperfine structures observed prove that the triorganyltin cations are chelated by o-benzosemiquinone. As the final product of these reactions, diamagnetic compounds can be isolated. As an example, the structure of 3,5-di-t-butyl-1,2-phenylenedioxy-bis(o-trifluoromethyl-phenyl)methanol-tin(IV) was determined by X-ray crystallography. The monomeric compound crystallizes in the space group P$\text{1}$ with a 10.451, b 11.905, c 15.379 Å, α 96.42, β 104.17, γ 111.43° and Z = 2. The penta-coordinated tin atom is 0.5 Å above the phenylenedioxy plane, which occupies one equatorial and one axial coordination site. The second axial position is occupied by the solvent methanol.