Solid mercury dihydride: mercurophilic bonding in molecular HgH(2) polymers

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Spectroscopy

Background:

• Mercury dihydride (HgH2) is a molecule of interest due to its potential covalent bonding.
• Previous studies on mercury hydrides have been limited, necessitating further investigation into their formation and properties.

Purpose of the Study:

• To synthesize and characterize the mercury dihydride (HgH2) molecule in a solid matrix.
• To investigate the structural and spectral properties of HgH2, including its dimer and trimer forms.
• To determine the thermal stability and decomposition behavior of solid HgH2.

Main Methods:

• Atomic mercury was subjected to mercury arc irradiation within a solid hydrogen matrix.
• Infrared (IR) spectroscopy was used to identify and characterize the HgH2 molecule and its aggregates.
• Annealing and controlled warming of the hydrogen matrix were employed to isolate solid HgH2.

Main Results:

• The linear HgH2 molecule was successfully synthesized, exhibiting characteristic IR absorptions at 1902 and 773 cm(-1).
• Annealing produced HgH2 dimer and trimer species.
• Solid HgH2, isolated after hydrogen sublimation, showed distinct IR absorptions at 1802 and 673 cm(-1) and decomposed between 150-170 K.

Conclusions:

• The formation of linear HgH2 in solid hydrogen is feasible via photochemical reactions.
• HgH2 exists as a covalent molecular solid with unique spectral signatures and thermal properties.
• This research provides foundational data for understanding mercury hydride chemistry in condensed phases.