Gas phase basicities of polyfunctional molecules. Part 6: Cyanides and isocyanides

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Organic Chemistry

Background:

• Gas-phase basicity (GB), proton affinity (PA), and protonation entropy (ΔpS°) are key thermochemical properties.
• Cyanides (nitriles) and isocyanides (isonitriles) are important functional groups with unique chemical behaviors.
• Previous data on their basicity may contain inaccuracies, necessitating a comprehensive reevaluation.

Purpose of the Study:

• To compile and critically evaluate existing structural and thermochemical data for cyanides and isocyanides.
• To present a unified and corrected dataset for gas-phase basicity, proton affinity, and protonation entropy.
• To provide new computational data on heats of formation for selected systems.

Main Methods:

• Reevaluation of experimental data using the NIST database scale for proton affinity and gas-phase basicity.
• Application of G4MP2 quantum chemistry computations for structural and energetic analysis.
• Systematic review of literature data across seven chapters covering various cyanide and isocyanide subclasses.

Main Results:

• Compilation of GB, PA, and ΔpS° values for approximately 110 cyanides and isocyanides.
• Identification and correction of erroneous values in existing literature data.
• Provision of computed heats of formation (ΔfH°) at 0 and 298 K for selected compounds.

Conclusions:

• The study provides a reliable and updated resource for the thermochemical properties of cyanides and isocyanides.
• The corrected data and new computational insights enhance understanding of their gas-phase chemistry.
• This review serves as a valuable reference for researchers in physical organic chemistry and computational chemistry.