Highly Strained Pn(CH)₃ (Pn = N, P, As, Sb, Bi) Tetrahedranes: Theoretical Characterization.

Area of Science:

• Computational chemistry
• Inorganic chemistry
• Quantum chemistry

Background:

• Experimental research confirmed phosphorus-substituted tetrahedranes.
• The Pn(CH)3 class of molecules, where Pn represents N, P, As, Sb, or Bi, has not been theoretically studied.

Purpose of the Study:

• To conduct the first theoretical investigations of the Pn(CH)3 molecular class.
• To analyze the geometric, electronic, and energetic properties of these novel compounds.

Main Methods:

• High-level theoretical calculations using CCSD(T)/aug-cc-pwCVTZ(-PP) for geometries.
• Harmonic vibrational frequency analysis to confirm stationary points.
• Natural Bond Orbital (NBO) methods for electronic structure analysis.

Main Results:

• The (CH)3 moiety remains geometrically consistent across different pnictogens.
• Pn-C bonds lengthen and C-Pn-C bond angles decrease with heavier pnictogens.
• Predicted strain energies range from 122.3 kcal mol⁻¹ (N(CH)3) to 99.4 kcal mol⁻¹ (Bi(CH)3).

Conclusions:

• Substituent effects and electron delocalization influence tetrahedrane stability.
• Heavier pnictogens lead to weaker Pn-C bonds due to delocalization.
• Findings provide a foundation for synthesizing novel pnictogen-substituted tetrahedranes.