The OC(2)F(5)(-), OCF(CF(3))(2)(-), and OCFCF(2)O(-) Anions: Preparation and Structure

Area of Science:

• Inorganic Chemistry
• Crystallography
• Computational Chemistry

Background:

• Synthesis of novel fluorinated organic compounds is crucial for developing new materials.
• Understanding the structural properties of these compounds provides insights into chemical bonding and reactivity.

Purpose of the Study:

• To synthesize and characterize new fluorinated compounds containing hexamethylpiperidinium (pip(+)) and tetramethylammonium (N(CH3)4(+)) cations.
• To investigate the crystal structures of selected compounds using single-crystal X-ray crystallography.
• To analyze the electronic structure and bonding characteristics, including negative hyperconjugation, and compare experimental findings with ab initio calculations.

Main Methods:

• Synthesis of four novel fluorinated compounds via reactions of fluoride salts with carbonyl fluoride precursors.
• Single-crystal X-ray diffraction analysis to determine the precise atomic arrangements and bond lengths.
• Ab initio calculations to model and predict the electronic structures and compare with experimental data.

Main Results:

• Successful synthesis of pip(+)CF(3)O(-), pip(+)CF(3)CF(2)O(-), pip(+)(CF(3))(2)CFO(-), and N(CH3)4(+)OCFCF(2)O(-).
• Detailed crystal structures were obtained for pip(+)CF(3)CF(2)O(-), pip(+)(CF(3))(2)CFO(-), and N(CH3)4(+)OCFCF(2)O(-), revealing specific lattice parameters and space groups.
• Anion structures indicate the presence of a negative hyperconjugation effect.
• The FCOCF(2)O(-) anion exhibits a non-symmetric structure with a near-planar cis-oxygen configuration, influenced by interionic forces.

Conclusions:

• The synthesized fluorinated compounds possess unique structural features.
• Negative hyperconjugation plays a significant role in the observed anion structures.
• Interionic forces are critical in dictating the specific structural arrangements in the solid state.
• Experimental findings are consistent with theoretical predictions from ab initio calculations.