“Click”‐Like η6‐Metalation/Demetalation of Aryl Iodides as a Means of Turning “ON/OFF” Halogen Bond Donor Functionality

η6‐Metalated aryl halides are recognized as a class of halogen bond (XB) donors. Click‐like η6‐metalation/demetalation of aryl iodides by cyclopentadienylruthenium(II) ([CpRuII]+) is shown to turn ON/OFF (amplify/suppress) XB donor functionality. [CpRu(MeCN)3][PF6] is shown to react quantitatively w...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2022-03, Vol.61 (13), p.e202115556-n/a
Main Authors: Kelly, Andrew W., Holman, K. Travis
Format: Article
Language:English
Subjects:
Amplification
Aromatic compounds
Cations
Co-Crystal
Crystal structure
Halides
Halogen Bond
Iodides
Magnetic resonance spectroscopy
NMR
NMR spectroscopy
Non-covalent Interactions
Nuclear magnetic resonance
Organometallics
Photochemicals
Salts
Supramolecular Chemistry
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Summary:η6‐Metalated aryl halides are recognized as a class of halogen bond (XB) donors. Click‐like η6‐metalation/demetalation of aryl iodides by cyclopentadienylruthenium(II) ([CpRuII]+) is shown to turn ON/OFF (amplify/suppress) XB donor functionality. [CpRu(MeCN)3][PF6] is shown to react quantitatively with iodobenzenes (ArIn, n=1,2) to yield [CpRu(η6‐ArIn)][PF6] compounds. Photochemical demetalation (405 nm) quantitatively reverts these compounds to ArIn and [CpRu(MeCN)3][PF6]. Crystal structures of [CpRu(ArXn)]+ salts show that the [CpRu(ArIn)]+ cations are strong, charge‐assisted XB donors analogous to iodopyridinium cations. XB‐induced association of [CpRu(C6H5I)]+ with diazobicyclo[2.2.2]octane (DABCO) is established by NMR spectroscopy. [CpRu(C6H5I)][BPh4] and [CpRu(1,4‐C6H4I2)][BPh4] co‐crystallize with DABCO and the structure of [CpRu(1,4‐C6H4I2)][BPh4]⋅DABCO⋅Et2O is reported. DFT calculations support amplification of the XBing capabilities of aryl iodides upon [CpRu]+‐metalation. Click On! η6‐Coordination of cationic cyclopentadienylruthenium(II) moieties is demonstrated to be a convenient, quantitative method for the click‐like activation of aryl iodides as halogen bond donors. Photochemical demetalation using violet LEDs in MeCN returns the metal to its starting material form and supresses halogen bonding functionality. The cycle provides a reversible “ON/OFF” switch for controlling the halogen bond donor strength of aryl iodides.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202115556