Isoselenocyanates with Sterically Encumbered Substituents─Synthesis, Structures, and Spectroscopic Properties.

Area of Science:

• Organometallic Chemistry
• Synthetic Chemistry
• Spectroscopy

Background:

• Isoselenocyanates are versatile organoselenium compounds.
• Understanding the electronic and steric effects of organic substituents is crucial for designing new selenium-containing molecules.

Purpose of the Study:

• To synthesize a diverse range of isoselenocyanates (SeCNR) with varying organic residues.
• To characterize these compounds using spectroscopic methods and X-ray diffraction.
• To investigate the influence of organic substituents on 77Se NMR chemical shifts and explore reaction mechanisms.

Main Methods:

• Synthesis of isoselenocyanates via reaction of isocyanides with elemental selenium.
• Characterization using X-ray diffraction, 77Se NMR spectroscopy, and other spectroscopic techniques.
• Density Functional Theory (DFT) modeling for chemical shift correlation.
• Isotopic labeling (13C) for coupling constant determination.

Main Results:

• Successful synthesis of a series of isoselenocyanates with sterically hindered and electronically diverse organic groups.
• Good to medium yields obtained, indicating the general suitability of the synthetic approach.
• 77Se NMR chemical shifts correlated well with DFT-modeled values.
• Experimental 77Se-13C couplings were determined for a specific isoselenocyanate.
• Identification of a selenourea byproduct, suggesting the influence of the supporting base on the reaction pathway.

Conclusions:

• The reaction of isocyanides with elemental selenium is a generally suitable method for synthesizing a wide array of isoselenocyanates.
• Organic substituents significantly influence the 77Se NMR chemical shifts, consistent with theoretical predictions.
• The choice of supporting base can impact the reaction outcome, potentially leading to different product types.