Molecular structure of tris(pentafluoroethyl)phosphane P(C2F5)3

Area of Science:

• Organophosphorus chemistry
• Fluorinated compounds
• Structural chemistry

Background:

• Tris(pentafluoroethyl)phosphane (P(C2F5)3) is a sterically hindered organophosphorus compound.
• Understanding its molecular structure is crucial for predicting its reactivity and applications.

Purpose of the Study:

• To determine the solid-state and gas-phase structures of P(C2F5)3.
• To compare experimental findings with quantum chemical calculations.
• To analyze the conformational preferences and steric properties (Tolman cone angle) of P(C2F5)3.

Main Methods:

• In situ single crystal growth and X-ray diffraction for solid-state structure determination.
• Gas-phase electron diffraction for gas-phase structure determination.
• Quantum chemical calculations at various theoretical levels.

Main Results:

• The preferred conformation of P(C2F5)3 exhibits C(3) symmetry with CF3 groups oriented towards the phosphorus lone pair.
• Estimated Tolman cone angles are 193° (solid) and 191° (gas).
• A second stable conformer with a smaller Tolman cone angle (171°) was identified, with an energy difference of 5 kJ mol(-1).

Conclusions:

• The study provides detailed structural insights into P(C2F5)3 in both solid and gas phases.
• Conformational analysis reveals significant steric bulk, influencing its properties.
• The findings are contextualized with related perfluoroalkyl and phosphine compounds.