Bildung und Kristallstruktur eines dimeren sauerstoffverbrückten Titanaminobisphenoxides

Formation and Crystal Structure of an Oxygen Bridged Titanium Amino Bisphenoxide Di‐(μ‐oxo)‐titan‐bis[aminobisphenoxide] ( 3 ) was obtained by reaction of (i‐Prop)₂TiL* ( 2 ) {L* = O‐4, 6‐(t‐Bu)₂C₆H₂‐2‐CH₂‐[1, 4‐N₂C₅H₁₀]‐2'‐CH₂‐4', 6'‐(t‐Bu)₂C₆H₂O] with water in a molar ratio 1:1 in diethylether. Both i‐Propyl moieties are substituted yielding the dimeric oxygen bridged amino bisphenoxide complex. The six coordinate Ti atoms are a result of Ti—N and Ti—O interactions of the corresponding atoms of the amino bisphenoxide ligand and the bridging O atoms. The central planar Ti₂O₂ ring may be considered as the general structural feature of the title compound: Space group P1¯, Z = 1, lattice dimensions at —60°C: a = 11.6899(4), b = 11.7873(4), c = 12.6462(4) Å, α = 98.070(1), β = 99.660(1), γ = 95.343(1)°, R₁ = 0.0469, wR₂ = 0.1049, GooF = 0.939.     

Höhere,kondensierte Ringsysteme. 5. Mitteilung[1]. Makrocyclen mit überbrückten 9, 10-Dihydrophenanthreneinheiten

Starting from 2, 7-diacetyl-9, 10-dihydrophenanthrene, 2, 7-dichloromethyl-9, 10-dihydrophenanthrene was synthesized through a serie of a new compounds. By a modified Wurtz reaction the dichloromethyl compound led to hexahydro-[2³] (2,7) phenanthrenophane and decahydro-[2⁵] (2,7) phenanthrenophane. [2³] (2,7) phenanthrenophane was obtained by dehydrogena tion of hexahydro-[2³] (2,7) phenanthrenophane with Pd/C. The structure of these new ring systems was confirmed by UV.-, NMR.- and mass spectroscopy.     

Radikalionen von überbrückten [14] Annulenen. Untersuchungen zum Frontorbitaleinfluss auf Reaktivität und Bindungszustand

Radical Ions of Bridged [14] Annulenes. Investigations on the Influence of Frontier Orbitals on Reactivity and Bonding The radical anions and the radical cations derived from trans-15, 16-dimethyl-1, 4:8,11-ethandiyliden[14]annulene ( 6 ), trans-15-methyl-1,4:8,11-ethandiyliden[14]annulene ( 7 ) and cis-15, 16-propano-1,4:8,11-ethandiyliden[14]annulene ( 8 ) are described. The hyperfine data of the radical anions 6, 7 and 8 resemble those of the structurally related radical anions of trans-10b, 10c-dimethyldihydropyrene ( 4 ) and trans-10b, 10c-dihydropyrene ( 5 ). This finding leads to the conclusion, that the change in the relative arragement of the saturated bridge within the fourteen-membered π-perimeter by passing from 4 (5) to 6 ( 7, 8 ) does not in fluence the energetic sequence of the lowest unoccupied molecular orbitals. The behavior of 6 and 7 towards oxidation parallels the photochemical reactivity of 4 . The hyperfine coupling constants of the radical cations derived from 6 and 7 indicate that the removal of an electron is accompanied by an isomerization of the molecular framework. The investigation of the electron transfer process gby cyclic voltammetry supports these findings. The radical cations prefer the cyclophane-like structures 6a and 7a , in which the central σ-bond (C(15)–C(16) bond) is broken.     

NMR-Untersuchungen an Dicyclopentadienderivaten: III—Stereochemische Zuordnung von überbrückten endo-Dicyclopentadienderivaten und deren Wagner-Meerwein-Umlagerungs-produkten mit Hilfe der NMR-Spektroskopie

The ¹H n.m.r. spectra of some substituted oxa- and azatetracycloundecanes are studied and selected examples analysed in detail with the aid of spin-spin decoupling and Eu(fod)₃ paramagnetic shift experiments. From the quoted ¹³C n.m.r. spectra the carbon resonances are assigned, using known substituent effects and paramagnetic shift values. The determined paramagnetic shift parameters ΔEu are discussed in respect of their contact and pseudocontact contributions.     

Synthesen überbrückter Bischinonmethide mit doppelter Acylketenaminal-Struktur

Syntheses of Bridged Bisquinonemethides with Double Acylketeneaminal Structure Starting with 1 , the synthesis of bis(tert-butyl)ester 2 is described. Some reactions including methylation of 2 to give 3 and 4 , ( 4 → 5 ) and deprotonation of 5 to 6 are reported. Possible structures of deprotonation products are discussed, based on NMR results.