15N-15N spin-spin coupling constants through intermolecular hydrogen bonds in the solid state

Area of Science:

• Nuclear Magnetic Resonance Spectroscopy
• Computational Chemistry
• Solid-State Chemistry

Background:

• Intermolecular spin-spin coupling constants (SSCCs) provide insights into molecular interactions and structures.
• Previous studies have focused on intermolecular SSCCs in solution-phase complexes.
• Understanding SSCCs in the solid state is crucial for characterizing powdered materials.

Purpose of the Study:

• To measure the 2hJNN intermolecular spin-spin coupling constant (SSCC) in a solid-state pyridinium tetrachlorogallate salt.
• To validate Density Functional Theory (DFT) methods for predicting intermolecular SSCCs in solid and solution phases.
• To compare experimental SSCC values with computational predictions.

Main Methods:

• Experimental measurement of the 2hJNN intermolecular SSCC using Nuclear Magnetic Resonance (NMR) spectroscopy on a powdered sample.
• Computational modeling using Density Functional Theory (DFT) with the B3LYP/6-311++G(d,p) level of theory.
• Comparison of experimental results with literature values for solution-phase complexes.

Main Results:

• A 2hJNN intermolecular SSCC of 10.2±0.4 Hz was experimentally determined for the powdered pyridinium tetrachlorogallate salt solvated by pyridine.
• DFT calculations successfully reproduced the experimentally measured 2hJNN SSCC.
• The computational method also accurately predicted literature values for intermolecular SSCCs in solution-phase complexes.

Conclusions:

• DFT calculations are reliable for predicting intermolecular SSCCs in both solid and solution states.
• This study demonstrates the feasibility of measuring and calculating intermolecular SSCCs in solid-state materials.
• The findings contribute to a deeper understanding of intermolecular interactions in crystalline organic salts.