Synthesis, Structure, and Electronic Properties of Bis(tetramethylcyclopropylidene)methane and Bis(cyclopropylidene)methane

Authors

  • Mirjana Eckert-Maksić,

    Corresponding author
    1. Ruder Boškovič Institute, Department of Organic Chemistry and Biochemistry, Bijenička 54, YU-41001 Zagreb, Croatia, Yugoslavia
    • Ruder Boškovič Institute, Department of Organic Chemistry and Biochemistry, Bijenička 54, YU-41001 Zagreb, Croatia, Yugoslavia
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  • Stephan Zöllner,

    1. Institut für Organische Chemie der Universität Hamburg, Martin-Luther-King-Platz 6, W-2000 Hamburg 13, FRG
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  • Wolfgang Göthling,

    1. Institut für Organische Chemie der Universität Hamburg, Martin-Luther-King-Platz 6, W-2000 Hamburg 13, FRG
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  • Roland Boese,

    1. Institut für Anorganische Chemie der Universität-GH Essen, Universitätsstraße 3–5, W-4300 Essen, FRG
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  • Ljiljana Maksimović,

    1. Ruder Boškovič Institute, Department of Organic Chemistry and Biochemistry, Bijenička 54, YU-41001 Zagreb, Croatia, Yugoslavia
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  • Reinhard Machinek,

    1. Institut für Organische Chemie der Universität Göttingen, Tammannstraße 2, W-3400 Göttingen, FRG
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  • Armin De Meijere

    Corresponding author
    1. Institut für Organische Chemie der Universität Hamburg, Martin-Luther-King-Platz 6, W-2000 Hamburg 13, FRG
    Current affiliation:
    1. Institut für Organische Chemie der Universität Göttingend, Tammannstraße 2, W-3400 Göttingen, FRG
    • Institut für Organische Chemie der Universität Hamburg, Martin-Luther-King-Platz 6, W-2000 Hamburg 13, FRG
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Abstract

Bis(tetramethylcyclopropylidene)methane (5) was prepared by treating 1-(dichloroethenylidene)-2,2,3,3-tetramethylcyclopropane (3) with tert-butyllithium in the presence of 2,3-dimethyl-2-butene. The parent allene 6 was obtained along a new route from bis(1-bromocyclopropyl) ketone (11) with low-valent titanium. Both 5 and 6 show unusually intense allene stretching bands in the IR spectra, and the signals of their central carbon atoms appear at remarkably high field in the 13C-NMR spectra. The unique structural features of 5 and 6, as evidenced by an X-ray crystal structural analysis of 5 and 1Jcc values, agree remarkably well with theoretical predictions made by semiempirical (MNDO) and ab initio (4-31G) calculations and on the basis of the simple picture offered by the hybridization model using the iterative maximum overlap (IMO) approach.

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