Chlorobis(pentafluoroethyl)phosphane: improved synthesis and molecular structure in the gas phase

Area of Science:

• Organophosphorus Chemistry
• Fluorine Chemistry
• Structural Chemistry

Background:

• Bis(pentafluoroethyl)phosphinous chloride ((C2F5)2PCl) is a valuable fluorinated organophosphorus compound.
• Previous synthesis routes for (C2F5)2PCl were inefficient.
• Understanding the structure and conformation of (C2F5)2PCl is crucial for its applications.

Purpose of the Study:

• To develop an improved and efficient synthesis protocol for (C2F5)2PCl.
• To elucidate the molecular structure and conformational landscape of (C2F5)2PCl using experimental and computational methods.

Main Methods:

• Improved synthesis starting from (C2F5)3PF2 involving reduction, hydrolysis, and chlorination.
• Gas electron diffraction (GED) for experimental structural determination.
• Quantum chemical calculations (MP2/TZVPP) to investigate potential energy surfaces and conformers.

Main Results:

• A 66% overall yield of (C2F5)2PCl was achieved through the improved synthesis.
• GED analysis indicated the presence of two conformers, with the most stable conformer comprising 61(5)% of the total.
• Experimental structural parameters from GED were in good agreement with MP2/TZVPP calculations, with a notable difference in the C-P-C angle.

Conclusions:

• The improved synthesis provides efficient access to (C2F5)2PCl.
• The molecular structure of (C2F5)2PCl is characterized by specific conformational preferences and a C-P-C bond angle of 98.2(4)° for the most abundant conformer.
• The combination of GED and quantum chemical calculations offers a powerful approach for studying the structure of fluorinated organophosphorus compounds.