Synthesis, Structures, and Spectroscopic Properties of 3-Aryl-5-(2-pyridyl)pyrazoles and Related Pyrazoles

Authors

  • Björn Schowtka,

    1. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena, Germany
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  • Christoph Müller,

    1. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena, Germany
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  • Helmar Görls,

    1. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena, Germany
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  • Matthias Westerhausen

    Corresponding author
    1. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena, Germany
    • Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena, Germany, Fax: +49-3641-948132

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  • Supporting Information for this article is available on the WWW under http://dx.doi.org/10.1002/zaac.201300637 or from the author.

Abstract

3-Aryl-5-(2-pyridyl)pyrazoles and related compounds are easily accessible via the reaction of the appropriate 1,3-diketone with hydrazine hydrate. The central pyrazole rings show a far-reaching equalization of the bond lengths. In the crystalline state dimeric and strand-like structures are observed due to the formation of intermolecular N–H···N hydrogen bridges between the pyrazole N–H functionality and a pyrazole or pyridyl base. The structures mainly depend on the steric demand of the aryl groups. Planar 3-aryl-5-(2-pyridyl)pyrazoles also show π stacking reducing the solubility in common organic solvents.

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