Molecular structure of thiourea

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• Understanding molecular structure is crucial for predicting chemical properties and reactivity.
• Thiourea's molecular structure has been previously studied, but precise equilibrium geometry requires advanced computational and experimental validation.

Purpose of the Study:

• To accurately determine the equilibrium molecular structure of thiourea.
• To investigate the potential energy surface and identify stable conformers.
• To combine theoretical calculations with experimental data for a high-precision structural determination.

Main Methods:

• High-level quantum-chemical calculations using coupled-cluster theory.
• Application of correlation-consistent basis sets up to quintuple-zeta.
• Extrapolation to the complete basis-set limit and inclusion of core-correlation effects.
• Utilizing experimental vibrational ground-state rotational constants for five isotopic species.

Main Results:

• The C(2) conformer of thiourea was identified as the only real minimum on the potential energy surface.
• Accurate equilibrium geometry was determined using both theoretical and experimental data.
• A semiexperimental equilibrium geometry for thiourea was established for the first time.

Conclusions:

• The C(2) conformer represents the true equilibrium structure of thiourea.
• The combined theoretical and experimental approach provides a highly accurate molecular structure.
• This study offers valuable data for further research in thiourea chemistry and related fields.