Chemical Bonding in Polarised Push-Pull Ethylenes

Area of Science:

• Organic Chemistry
• Crystallography
• Computational Chemistry

Background:

• 1,1-Diamino-2,2-bis(triflyl)ethylenes represent a unique class of organic compounds.
• Understanding the electronic structure and bonding in these molecules is crucial for predicting their chemical behavior.
• Previous studies may not have fully elucidated the bonding nuances in both twisted and planar conformations.

Purpose of the Study:

• To synthesize 1,1-diamino-2,2-bis(triflyl)ethylenes with varying structural conformations.
• To experimentally investigate and analyze the bonding properties of these compounds.
• To elucidate the contribution of resonance structures to the overall electronic configuration.

Main Methods:

• Synthesis of twisted and planar 1,1-diamino-2,2-bis(triflyl)ethylene isomers.
• High-resolution X-ray diffraction for structural determination.
• X-ray wavefunction refinement (XWR) for detailed electronic structure analysis.

Main Results:

• Successful synthesis of both twisted and planar 1,1-diamino-2,2-bis(triflyl)ethylene derivatives.
• XWR analysis revealed a dominant charge-separated resonance structure in the twisted isomer.
• The planar isomer exhibited significant π-bonding character alongside a considerable contribution from charge-separated resonance structures.

Conclusions:

• The structural conformation significantly influences the electronic distribution and bonding in 1,1-diamino-2,2-bis(triflyl)ethylenes.
• Charge-separated resonance structures play a crucial role in the bonding of these compounds, particularly in the twisted form.
• Experimental X-ray wavefunction refinement provides deep insights into the intricate bonding mechanisms of novel organic molecules.