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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Isatin 3-semicarbazone and 1-methylisatin 3-semicarbazone
G Pelosi1, C Pelizzi, M Belicchi Ferrari
1Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Parco Area delle Scienze 17/A, 43100 Parma, Italy. giorgio@unipr.it
Summary
Two semicarbazone compounds share Z/E configurations and intramolecular hydrogen bonds. A methyl group on the isatin nitrogen atom influences crystal packing, leading to distinct chain and helical arrangements in their solid states.
Area of Science:
- Crystallography
- Organic Chemistry
- Molecular Structure
Background:
- Semicarbazones are derivatives of ketones and aldehydes.
- Isatin derivatives are known for diverse biological activities.
- Understanding molecular configuration and crystal packing is crucial for material properties.
Purpose of the Study:
- To determine and compare the crystal structures of two isatin-3-semicarbazone derivatives.
- To investigate the influence of N-methylation on the molecular configuration and solid-state packing.
- To analyze the role of intramolecular hydrogen bonding in stabilizing the observed configurations.
Main Methods:
- Single-crystal X-ray diffraction analysis was performed on both compounds.
- Geometric parameters, including bond lengths, angles, and torsion angles, were analyzed.
- Intermolecular and intramolecular interactions, particularly hydrogen bonds, were identified and characterized.
- Crystal packing arrangements were visualized and compared.
Main Results:
- Both 2,3-dihydro-1H-indole-2,3-dione 3-semicarbazone (I) and 1-methyl-2,3-dihydro-1H-indole-2,3-dione 3-semicarbazone (II) exhibit a Z configuration around the imine C=N bond and an E configuration around the C(O)-NH2 bond.
- Two intramolecular hydrogen bonds were identified, stabilizing these configurations in both molecules.
- Compound (I) displays molecular chains in the (102) crystallographic plane, oriented perpendicular to the b axis.
- Compound (II) shows a helical arrangement of molecules parallel to the a crystallographic screw axis, attributed to the N-methyl group.
Conclusions:
- The N-methyl group on the isatin core significantly impacts the crystal packing of semicarbazone derivatives.
- Despite structural similarities in solution or gas phase, solid-state arrangements can differ substantially due to subtle molecular changes.
- The study provides insights into structure-property relationships in isatin derivatives, relevant for crystal engineering and materials science.
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