Experimental and Computational ⁷⁷Se NMR Spectroscopic Study on Selenaborane Cluster Compounds

Area of Science:

• Inorganic Chemistry
• Nuclear Magnetic Resonance Spectroscopy
• Boron and Selenium Cluster Chemistry

Background:

• Selenaborane clusters are complex inorganic compounds with diverse structures.
• Nuclear Magnetic Resonance (NMR) spectroscopy is crucial for characterizing these molecules.
• Understanding the relationship between structure and NMR chemical shifts is essential for accurate compound identification.

Purpose of the Study:

• To investigate the correlation between calculated and measured ⁷⁷Se NMR chemical shifts in selenaborane clusters.
• To develop a predictive tool for ⁷⁷Se NMR chemical shifts based on intracluster coordination.
• To facilitate the assignment of ⁷⁷Se NMR resonances in complex selenaborane systems.

Main Methods:

• Calculation of ⁷⁷Se NMR chemical shifts using density functional theory (DFT).
• Measurement of ⁷⁷Se NMR chemical shifts for 13 diverse selenaborane cluster compounds (19 selenium centers).
• Analysis of the relationship between chemical shifts and intracluster selenium coordination.

Main Results:

• A strong correlation was observed between calculated and measured ⁷⁷Se NMR chemical shifts.
• A linear relationship was established, enabling prediction of chemical shift ranges.
• Relative chemical shifts were consistent, allowing confident assignment of selenium resonances.
• A new macropolyhedral selenaborane, Se₂B₁₈H₂₀, was synthesized and characterized.

Conclusions:

• ⁷⁷Se NMR chemical shifts are predictable based on selenium atom coordination in selenaborane clusters.
• The developed correlation serves as a valuable tool for reducing experimental time and effort.
• Accurate assignment of ⁷⁷Se NMR signals is achievable even with lower-level DFT calculations.
• This work advances the understanding and characterization of complex boron-selenium cluster compounds.