Electronic structures of main-group carbene analogues

Area of Science:

• Computational Chemistry
• Inorganic Chemistry
• Organic Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile compounds with unique electronic properties.
• Understanding main-group analogues of NHCs is crucial for expanding carbene chemistry.
• Previous studies have explored individual main-group carbenes, but a systematic comparison is lacking.

Purpose of the Study:

• To systematically analyze and compare the electronic structures of 15 group 13-16 carbene analogues.
• To investigate the electronic similarities and differences relative to the parent N-heterocyclic carbene, imidazol-2-ylidene.
• To evaluate the aromaticity and donor-acceptor capabilities of these main-group carbene analogues.

Main Methods:

• Utilized various quantum chemical methods for theoretical analysis.
• Performed comparative studies against imidazol-2-ylidene.
• Assessed electronic structure, charge distribution, aromaticity, and donor-acceptor properties.

Main Results:

• Electronic structures range from C=C localized (Group 13) to C=N localized (Group 16), deviating from NHC.
• Stibenium ions and chalcogenium dications possess two lone pairs, unlike NHCs.
• Electronic structure changes correlate with system charge, varying from anionic to dicationic across the periodic table.
• All analogues exhibit some aromatic character, with Group 15 systems showing significant aromaticity.

Conclusions:

• The electronic structures of main-group carbene analogues are diverse and influenced by periodic trends and charge.
• These compounds present distinct electronic features compared to NHCs, offering new avenues in carbene chemistry.
• The study provides a comprehensive understanding of p-block carbene analogues, highlighting their aromaticity and electronic behavior.