Halogen-Bonded Co-Crystals of Aromatic N-oxides: Polydentate Acceptors for Halogen and Hydrogen Bonds
Department of Chemistry, University of Jyvaskyla, P.O. Box 35, FI-40014 Jyvaskyla, Finland
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Academic Editors: Peter Politzer and Jane S. Murray
Crystals 2017, 7(7), 214; https://doi.org/10.3390/cryst7070214
Received: 7 June 2017
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Revised: 6 July 2017
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Accepted: 7 July 2017
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Published: 11 July 2017
(This article belongs to the Special Issue Analysis of Halogen and Other σ-Hole Bonds in Crystals)
Seventeen new halogen-bonded co-crystals characterized by single crystal X-ray analysis are presented from 8 × 4 combinations using methyl-substituted pyridine N-oxides and 1,ω-diiodoperfluoroalkanes. The N−O group in six of 17 co-crystals is monodentate and 11 have μ-O,O bidentate halogen bond acceptor modes. Remarkably, the N−O group in co-crystals of 3-methyl-, 4-methyl- and 3,4-dimethylpyridineN-oxides with octafluoro-1,4-diiodobutane acted as a μ-O,O,O,O halogen and hydrogen bond acceptor, while acting as a μ-O,O,O acceptor in the co-crystal of 2,5-dimethylpyridineN-oxide and tetrafluoro-1,2-diiodoethane. The C−H···O−N hydrogen bonds demonstrated the polydentate cooperativity of the N−O group as a mixed halogen-hydrogen bond acceptor. The co-crystal of 2,4,6-trimethylpyridineN-oxide and dodecafluoro-1,6-diiodohexane exhibited C−I···O−−N+ halogen bonds with RXB value 0.76, the shortest of its kind compared to previously reported structures. The RXB values between 0.76 and 0.83 suggested that the C−I···O−−N halogen bonds are moderately strong compared to our previously studied N−−I···O−−N system, with RXB in the order 0.66.
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Keywords:
halogen bond; hydrogen bond; aromatic N-oxides; perfluoroalkyl; diiodoperfluoroalkanes; polydentate; N−O group; cooperativity; C−H···O interactions
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MDPI and ACS Style
Puttreddy, R.; Topić, F.; Valkonen, A.; Rissanen, K. Halogen-Bonded Co-Crystals of Aromatic N-oxides: Polydentate Acceptors for Halogen and Hydrogen Bonds. Crystals 2017, 7, 214. https://doi.org/10.3390/cryst7070214
AMA Style
Puttreddy R, Topić F, Valkonen A, Rissanen K. Halogen-Bonded Co-Crystals of Aromatic N-oxides: Polydentate Acceptors for Halogen and Hydrogen Bonds. Crystals. 2017; 7(7):214. https://doi.org/10.3390/cryst7070214
Chicago/Turabian StylePuttreddy, Rakesh, Filip Topić, Arto Valkonen, and Kari Rissanen. 2017. "Halogen-Bonded Co-Crystals of Aromatic N-oxides: Polydentate Acceptors for Halogen and Hydrogen Bonds" Crystals 7, no. 7: 214. https://doi.org/10.3390/cryst7070214
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