Computational Studies of Bridging Structures and Isomerism in Substituted Disilynes

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Inorganic Chemistry

Background:

• Disilyne molecules are silicon analogs of alkynes.
• Understanding their structure and reactivity is crucial for silicon chemistry.
• Previous studies have explored related systems like C2X2 and C2HX.

Purpose of the Study:

• To investigate the structures and energetics of substituted disilyne molecules (Si2Li2 and Si2HX).
• To identify isomeric forms and transition states.
• To compare computational methods for accuracy and efficiency.

Main Methods:

• High-level ab initio calculations using coupled cluster with double excitation, full configuration interaction (CCSD(T)) and CCSD(T)-F12 methods.
• Employing the cc-pVTZ-F12 and cc-pV(6+d)Z basis sets.
• Calculations of optimized geometries, relative energies, and harmonic vibration frequencies.

Main Results:

• Existence of several isomeric forms and transition states confirmed for Si2Li2 and Si2HX.
• Bridging structures were found in all investigated cases.
• CCSD(T)-F12/cc-pVTZ-F12 calculations showed comparable accuracy to CCSD(T)/cc-pV(6+d)Z at lower computational cost.

Conclusions:

• The study provides detailed structural and energetic information for substituted disilynes.
• Bridging structures are a common feature in these silicon compounds.
• The CCSD(T)-F12/cc-pVTZ-F12 method is recommended as an efficient and accurate alternative for future studies.