Strongly bound noncovalent (SO3)n:H2CO complexes (n = 1, 2)

Area of Science:

• Computational chemistry
• Molecular interactions
• Supramolecular chemistry

Background:

• Sulfur trioxide (SO3) is a highly reactive molecule.
• Formaldehyde (H2CO) is a fundamental organic compound.
• Understanding non-covalent interactions is crucial in chemistry.

Purpose of the Study:

• To investigate the potential energy surfaces (PES) of SO3:H2CO and (SO3)2:H2CO complexes.
• To characterize the nature and strength of intermolecular forces within these complexes.
• To explore cooperative effects in trimolecular systems.

Main Methods:

• Ab initio calculations using the MP2/aug-cc-pVDZ level of theory.
• Analysis of electrostatic potentials.
• Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) analyses.
• Energy decomposition analysis and electron density redistribution maps.

Main Results:

• SO3:H2CO heterodimers and (SO3)2:H2CO heterotrimers are stabilized by SO chalcogen bonds and weaker CHO/OC bonds.
• The most stable dimer possesses an interaction energy > 10 kcal mol(-1).
• Trimers show strong binding (> 20 kcal mol(-1)) with cooperative effects and three-body interaction energies near 3 kcal mol(-1).

Conclusions:

• SO3 and H2CO form robust complexes driven by specific non-covalent interactions.
• The studied trimers exhibit significant positive cooperativity, enhancing binding.
• These findings provide insights into the assembly and stability of molecular complexes involving SO3.