Methyl/phenyl attraction by CH/π interaction in 1,2-substitution patterns.
Henri Brunner1, Takashi Tsuno, Gábor Balázs
1Institut für Anorganische Chemie, Universität Regensburg , 93040 Regensburg, Germany.
In organic compounds with 1,2-Me,Ph substitution, methyl groups form CH/π bonds with phenyl rings, causing characteristic tilting. This interaction shortens specific atomic distances, influencing molecular geometry and stability.
Area of Science:
- Organic Chemistry
- Supramolecular Chemistry
- Chemical Crystallography
Background:
- The 1,2-Me,Ph substitution pattern in organic molecules involves specific spatial arrangements between methyl and phenyl groups.
- Non-covalent interactions, such as CH/π bonding, play a crucial role in determining molecular conformation and properties.
Purpose of the Study:
- To investigate the formation and impact of CH/π bonds in organic compounds with 1,2-Me,Ph substitution.
- To analyze the relationship between torsion angles and the presence of CH/π interactions in various molecular structures.
Main Methods:
- Utilized the Cambridge Structural Database (CSD) to search for specific substructures (Me-C═C-Ph, Me-C-C-Ph, Me-C-N-Ph) with 1,2-Me,Ph substitution.
- Analyzed torsion angles (C(Me)-C-C-C(i)) to correlate with C(Me)-C(o) and C(Me)-C(i) distances.
- Supported findings with computational calculations.
Main Results:
- Observed that methyl groups form CH/π bonds with ortho carbon atoms of phenyl rings, leading to phenyl ring tilting.
- Found that CH/π interactions occur for torsion angles up to 80°, shortening C(Me)-C(o) distances below van der Waals limits.
- Determined that torsion angles greater than 80° prevent CH/π interactions due to elongated C(Me)-C(i) and C(Me)-C(o) distances.
Conclusions:
- The 1,2-Me,Ph substitution motif significantly influences molecular conformation through CH/π bonding.
- Torsion angles are critical determinants of CH/π interaction occurrence and strength in these systems.
- The study provides insights into the geometric consequences of non-covalent interactions in organic molecules.
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