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  • 1
    ISSN: 1434-1948
    Keywords: Hydrogen bonds ; Indium ; Lithium ; Nitrogen heterocycles ; Zinc ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The lithiation of 2,5-di(tert-butyl)pyrrole (1) yields bis(tetrahydrofuran)lithium 2,5-di(tert-butyl)pyrrolide (2), which is monomeric in solution as well as in the solid state. Due to the coordination number of three for the lithium atom, short Li-O and Li-N bond lengths of 193 pm are observed. The metathesis reaction of 2 with tris(trimethylsilyl)-methylzinc chloride (3) gives colorless bis[tris(trimethyl-silyl)methylzinc] chloride 2,5-di(tert-butyl)pyrrolide (4). The pyrrolide ligand and the chlorine atom bridge the zinc atoms. One of the zinc atoms is bonded to the nitrogen atom of the pyrrolide substituent, while the other bonds to the opposite C-C bond. At 215 pm, the Zn-N bond is very long compared to those in alkylzinc amides, whereas the Zn-C distances lie in the range of Zn-C bond lengths found between zinc and η5-bonded cyclopentadienide ligands. The molecular structures of 1 and of the low-melting THF adduct 1·thf show a similar 2,5-di(tert-butyl)pyrrole molecule, but in the latter case a weak N-H···O bond is observed (N-H 97 pm, O···H 199 pm).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0009-2940
    Keywords: Lithium ; Zine ; Dibenzylzinc ; Tmeda complexes ; Heteroleptic alkylzinc amide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of lithium phenyl(trimethylsilyl)methanide with phenyl(trimethylsilyl)methylzinc chloride-tmeda in the presence of tmeda yields the addition product, a bis(tmeda)-lithium dialkylchlorozincate. The elimination of lithium chloride leads to the formation of a tmeda adduct of bis[phenyl-(trimethylsilyl)methyl]zinc. The metathesis reaction of phenyl(trimethylsilyl)methylzinc chloride-tmeda with lithium tris(trimethylsilyl)silylamide allows the isolation of the corresponding heteroleptic tmeda complex of an alkylzinc amide. The metalation of phenyl(trimethylstannyl)methane with butyllithium yields the transmetalation product benzyllithium. From the metathesis reaction of this lithium base with anhydrous zinc(II) chloride in the presence of tmeda, the tmeda adduct of dibenzylzinc crystallizes. The molecular structures of (tmeda)Li—CH(GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 are reported. Whereas lithium bonds in an η3-fashion, the zinc atom forms a σ(Zn—C) bond. The extremely wide Zn—N—Si angle in (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 of 157° is remarkable.
    Additional Material: 4 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Barium 1-Aza-3-phosphapropenide ; 1,3-Azaphosphaallyl Anion ; NMR ; X-ray Structure Determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, NMR Spectroscopic Characterization and Structure of Bis(1,2-dimethoxyethane-O,O′)barium Bis[1,3-bis(trimethylsilyl)-2-phenyl-1-aza-3-phosphapropenide]Barium-bis[bis(trimethylsilyl)phosphanide] 1 reacts with two equivalents of benzonitrile to give barium bis[1,3-bis(trimethylsilyl)-2-phenyl-1-aza-3-phosphapropenide]; the choice of the solvent determines whether a tris-(tetrahydrofuran)- or a bis(1,2-dimethoxyethane)-complex 2 can be isolated. 2 crystallizes from DME as red cuboids (monoclinic, C2/c, a = 1627.0(3), b = 1836.6(3), c = 1602.5(2) pm; β = 96.071(12)°; V = 4761.7(12); Z = 4; wR2 = 0.0851). The phosphorus atom displays a pyramidal surrounding in contrast to the planar coordination sphere of the nitrogen atom. In addition a twist within the P—C—N skeleton of the heteroallyl anion is observed.
    Notes: Barium-bis[bis(trimethylsilyl)phosphanid] 1 reagiert mit zwei Äquivalenten Benzonitril zu Barium-bis[1,3-bis(trimethylsilyl)-2-phenyl-1-aza-3-phosphapropenid]; durch die Wahl des Lösungsmittels läßt sich entweder der Tris(tetrahydrofuran)- oder der Bis(1,2-dimethoxyethan)-Komplex 2 isolieren. Verbindung 2 kristallisiert aus DME in Form roter Würfel aus (monoklin. C2/c, a = 1627,0(3), b = 1836,6(3), c = 1602,5(2) pm; β = 96,071(12)°; V = 4761,7(12); Z = 4; wR2 = 0,0851). Während die Koordinationssphäre des Stickstoffatoms planar ist, befindet sich das Phosphoratom in einer pyramidalen Umgebung. Zusätzlich beobachtet man im 1-Aza-3-phosphapropenid-Anion eine leichte Verdrillung.
    Additional Material: 3 Ill.
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