Identification of Photochemically Generated Volatile Species of Ruthenium and Osmium Using Direct Analysis in Real...

Area of Science:

• Analytical Chemistry
• Inorganic Chemistry
• Mass Spectrometry

Background:

• Volatile metal carbonyls are challenging to identify due to their reactivity.
• Photochemical vapor generation (PVG) offers a method for generating volatile metal species.
• Direct analysis in real time (DART) high-resolution mass spectrometry (HRMS) provides sensitive detection capabilities.

Purpose of the Study:

• To identify unknown volatile carbonyls of Ruthenium (Ru) and Osmium (Os) generated via UV photolysis.
• To investigate the utility of coupling PVG with N2-based DART-HRMS for analyzing metal carbonyls.
• To elucidate the fragmentation and ionization pathways of metal carbonyls under DART conditions.

Main Methods:

• Coupling of Photochemical Vapor Generation (PVG) with Direct Analysis in Real Time (DART) High-Resolution Mass Spectrometry (HRMS).
• Utilizing N2 as the discharge gas in DART-HRMS.
• Employing various photochemical media, including formic acid (HCOOH), nitric acid (HNO3), hydrogen peroxide (H2O2), and acetic acid (CH3COOH), with transition metal mediators (Co2+, Fe2+).
• Analysis of volatile standards like W(CO)6 and Fe(CO)5 to understand ionization mechanisms.

Main Results:

• PVG-DART-HRMS successfully identified mononuclear Ru(CO)5 and Os(CO)5 generated from HCOOH-based media.
• Oxidative conditions using H2O2 or HNO3 led to the identification of OsO4.
• The presence of Co2+ as a mediator resulted in the co-generation of Co(CO)4H, complicating analysis.
• DART-HRMS revealed significant structural changes in carbonyls, including CO loss, oxidation, and hydration.

Conclusions:

• The combined PVG-DART-HRMS technique is effective for identifying volatile Ru and Os carbonyls.
• The method provides insights into the formation and stability of metal carbonyls under photochemical conditions.
• Understanding DART ionization behavior is crucial for accurate identification of metal carbonyl species.