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Updated: Aug 7, 2026
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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Mixed dicationic and monocationic benzidine species in the proton-transfer compound of benzidine with
Graham Smith1, Urs D Wermuth, Jonathan M White
1School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. g.smith@qut.edu.au
Summary
This study details the crystal structure of a proton-transfer compound involving benzidine and dinitrosalicylic acid. It reveals both diprotonated and monoprotonated benzidine cations interacting through hydrogen bonding and pi-pi interactions.
Area of Science:
- Crystallography
- Supramolecular Chemistry
- Chemical Physics
Background:
- Proton-transfer compounds are crucial in understanding chemical interactions and material properties.
- Benzidine and dinitrosalicylic acid are key components in forming such complexes.
- Crystal structure analysis provides fundamental insights into molecular arrangements and bonding.
Purpose of the Study:
- To elucidate the crystal structure of the proton-transfer compound formed between 1,1'-biphenyl-4,4'-diamine (benzidine) and 3,5-dinitrosalicylic acid.
- To characterize the protonation states and hydrogen bonding networks within the crystal lattice.
- To investigate the intermolecular interactions, including pi-pi interactions, that stabilize the structure.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the precise atomic arrangement.
- Analysis of crystallographic data identified the protonation states of benzidine cations.
- Hydrogen bonding and pi-pi interactions were analyzed to understand the supramolecular assembly.
Main Results:
- The crystal structure confirmed the presence of both diprotonated and monoprotonated benzidine cations.
- Diprotonated benzidine cations were located at inversion centers, while monoprotonated cations occupied general positions.
- Extensive hydrogen bonding networks involving amine groups, salicylate anions, and ethanol solvent molecules were observed.
- Significant inter-ring anion-anion and anion-monocation pi-pi interactions contribute to the 3D framework structure.
Conclusions:
- The study successfully characterized the complex crystal structure of the benzidine-dinitrosalicylic acid proton-transfer compound.
- The findings highlight the role of hydrogen bonding and pi-pi interactions in organizing proton-transfer systems.
- This detailed structural information contributes to the understanding of supramolecular chemistry and crystal engineering.
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