Synthesis, purification, and structural characterization of the dimethyldiselenoarsinate anion

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Biochemistry

Background:

• Arsenic and selenium are toxic metalloids with complex environmental speciation.
• Understanding novel arsenic-selenium interactions is crucial for environmental and health risk assessment.

Purpose of the Study:

• To synthesize and characterize a novel arsenic-selenium solution species.
• To elucidate the structure and bonding of the synthesized compound.

Main Methods:

• Synthesis of the arsenic-selenium species using sodium selenite, sodium dimethylarsinate, and glutathione.
• Characterization using selenium-77 nuclear magnetic resonance ((77)Se NMR) spectroscopy.
• Size-exclusion chromatography (SEC) coupled with inductively coupled plasma atomic emission spectrometry (ICP-AES).
• Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS-MS).
• Extended X-ray absorption fine structure (EXAFS) spectroscopy for arsenic (As) and selenium (Se).

Main Results:

• A novel arsenic-selenium species was successfully synthesized in aqueous solution.
• Spectroscopic data confirmed an arsenic-selenium moiety with an As:Se molar ratio of 1:2.
• Mass spectrometry identified the molecular mass and fragmentation patterns.
• EXAFS analysis revealed specific As-C and As-Se bond distances.

Conclusions:

• The novel solution species was identified as the dimethyldiselenoarsinate anion.
• This study provides detailed structural and chemical insights into arsenic-selenium compounds.
• The findings contribute to the understanding of metalloid speciation and biogeochemical cycling.