High-pressure induced switching between halogen and hydrogen bonding regimes in 1,4-dioxane iodine monochloride †

Jones, Richard H.; Bull, Craig L.; Knight, Kevin S.; Marshall, William G.

Abstract

The structure of the complex formed between 1,4-dioxane and iodine monochloride has been studied as a function of pressure using neutron powder diffraction. Initial compression was accompanied by a decrease in the O⋯I halogen bond length together with an increase in the intramolecular I–Cl bond length. Two phase transitions were observed at ∼2.8 and ∼4.5 GPa. The transient intermediate phase coexists with the ambient pressure phase during the initial phase transition and with the final high-pressure phase at the second phase transition, before its disappearance. The driving force for the first phase transition is a shearing motion of the complex causing a reduction in the dipolar interaction of two I–Cl moieties. The formation of the highest pressure phase is accompanied by a net reduction of 2 C–H⋯Cl hydrogen bonds per formula unit. From these changes we conclude that Cl⋯Cl halogen bonds are favoured over C–H⋯Cl hydrogen bonds at high pressures.

• Journal Article Type: Article
• Acceptance Date: Jun 21, 2023
• Online Publication Date: Jul 3, 2023
• Deposit Date: Jul 10, 2023
• Publicly Available Date: Jul 3, 2023
• Journal: CrystEngComm
• Electronic ISSN: 1466-8033
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 25
• Issue: 29
• Pages: 4146-4156
• DOI: https://doi.org/10.1039/d3ce00362k