Ditechnetium Heptoxide Revisited: Solid-State, Gas-Phase, and Theoretical Studies

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Computational Chemistry

Background:

• Technetium heptoxide (Tc2O7) is a compound of a synthetic element with limited characterization data.
• Understanding the structural and chemical properties of Tc2O7 is crucial for its handling and potential applications.

Purpose of the Study:

• To synthesize and characterize technetium heptoxide (Tc2O7).
• To elucidate the solid-state structure and gas-phase behavior of Tc2O7 using experimental and theoretical methods.

Main Methods:

• Synthesis of Tc2O7 via oxidation of TcO2.
• Single-crystal X-ray diffraction for solid-state structure determination.
• Electron-impact mass spectrometry (EI-MS) for gas-phase analysis.
• Density functional theory (DFT) for computational modeling.

Main Results:

• Tc2O7 crystallizes as a molecular solid in the orthorhombic space group Pbca.
• The solid-state Tc2O7 molecule exhibits a linear Tc-O-Tc bridge (180.0°).
• EI-MS reveals mononuclear (TcO3, TcO2) and dinuclear (Tc2O7, Tc2O5) species in the gas phase.
• DFT calculations confirm the experimental solid-state structure and predict a bent gas-phase geometry (156.5°).

Conclusions:

• The study provides a comprehensive characterization of Tc2O7, detailing its synthesis, solid-state structure, and gas-phase chemistry.
• A significant difference in geometry between the solid-state (linear) and gas-phase (bent) Tc2O7 molecule was observed.
• The findings highlight distinct gas-phase chemistry between technetium and rhenium heptoxides.