The Effect of Pressure on Halogen Bonding in 4-Iodobenzonitrile

Journal Article · 26 May 2019 · Molecules

DOI: https://doi.org/10.3390/molecules24102018 · OSTI ID:1518567

Giordano, Nico  ^[1]; Afanasjevs, Sergejs ^[2]; Beavers, Christine M. ^[3]; Hobday, Claire L.  ^[4]; Kamenev, Konstantin V. ^[2]; O’Bannon, Earl F.  ^[5]; Ruiz-Fuertes, Javier  ^[6]; Teat, Simon J.  ^[7]; Valiente, Rafael ^[8]; Parsons, Simon ^[4]

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1. Univ. of Edinburgh, Scotland (United Kingdom). Centre for Science at Extreme Conditions and EaStCHEM School of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
2. Univ. of Edinburgh, Scotland (United Kingdom). Centre for Science at Extreme Conditions and School of Engineering
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Univ. of California, Santa Cruz, CA (United States). Dept. of Earth & Planetary Sciences; Science and Technology Facilities Council (STFC), Harwell Campus, Oxford (United Kingdom). Rutherford Appleton Lab., Diamond Light Source, Ltd.
4. Univ. of Edinburgh, Scotland (United Kingdom). Centre for Science at Extreme Conditions and EaStCHEM School of Chemistry
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Univ. of California, Santa Cruz, CA (United States). Dept. of Earth & Planetary Sciences; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences
6. Univ. de Cantabria, Santander (Spain). DCITIMAC, Facultad de Ciencias
7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
8. Univ. de Cantabria-IDIVAL, Santander (Spain)

The crystal structure of 4-iodobenzonitrile, which is monoclinic (space group I2/a) under ambient conditions, contains chains of molecules linked through C≡N···I halogen-bonds. The chains interact through CH···I, CH···N and π-stacking contacts. The crystal structure remains in the same phase up to 5.0 GPa, the b axis compressing by 3.3%, and the a and c axes by 12.3 and 10.9 %. Since the chains are exactly aligned with the crystallographic b axis these data characterise the compressibility of the I···N interaction relative to the inter-chain interactions, and indicate that the halogen bond is the most robust intermolecular interaction in the structure, shortening from 3.168(4) at ambient pressure to 2.840(1) Å at 5.0 GPa. The π∙∙∙π contacts are most sensitive to pressure, and in one case the perpendicular stacking distance shortens from 3.6420(8) to 3.139(4) Å. Packing energy calculations (PIXEL) indicate that the π∙∙∙π interactions have been distorted into a destabilising region of their potentials at 5.0 GPa. The structure undergoes a transition to a triclinic (P$$\bar{1}$$) phase at 5.5 GPa. Over the course of the transition, the initially colourless and transparent crystal darkens on account of formation of microscopic cracks. The resistance drops by 10% and the optical transmittance drops by almost two orders of magnitude. The I···N bond increases in length to 2.928(10) Å and become less linear [-1 and the mixed C-I/I..N stretching frequency observed by Raman spectroscopy increases from 249 to 252 cm^-1. The driving force of the transition is shown to be relief of strain built-up in the π∙∙∙π interactions rather than minimisation of the molar volume. The triclinic phase persists up to 8.1 GPa.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1518567
• Alternate ID(s): OSTI ID: 1529688; OSTI ID: 1572012
• Report Number(s): LLNL-JRNL--773221; {"Journal ID: ISSN MOLEFW",965469,"Journal ID: ISSN 1420-3049"}
• Journal Information: Molecules, Journal Name: Molecules Journal Issue: 10 Vol. 24; ISSN MOLEFW; ISSN 1420-3049
• Publisher: MDPICopyright Statement
• Country of Publication: United States
• Language: English