Characterization of persistent intramolecular C-H...X(N,O) bonds in solid state and solution.

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Computational Chemistry

Background:

• Intramolecular interactions like hydrogen bonds significantly influence molecular conformation and properties.
• Non-classic hydrogen bonds (e.g., CH...X) are increasingly recognized for their role in stabilizing structures.
• Ortho-carborane cages offer unique structural frameworks for studying such interactions.

Purpose of the Study:

• To investigate the formation and persistence of intramolecular CH...X(N,O) bonds in solution.
• To analyze the structural and electronic properties of two distinct rotamers containing an ortho-carborane cage, amide, and quinoline.
• To evaluate the strength and characteristics of these non-classic hydrogen interactions.

Main Methods:

• X-ray crystallography for solid-state structural determination.
• Nuclear Magnetic Resonance (NMR) spectroscopy for solution-state analysis.
• Theoretical ab initio calculations to complement experimental data and validate findings.

Main Results:

• Experimental and computational data confirmed the presence and persistence of intramolecular CH...X(N,O) bonds in both studied rotamers.
• Accurate bonding and geometric parameters for the CH...X interaction were extracted.
• The strength of these non-classic hydrogen interactions was quantified.

Conclusions:

• Intramolecular CH...X bonds are stronger and more prevalent than previously assumed.
• These findings offer new insights into the fundamental theory of non-classic hydrogen bonding.
• The studied molecule, with its unique structural features, shows potential for applications such as boron neutron capture therapy.