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Characterization of inorganic coordination complexes by matrix‐assisted laser desorption/ionization mass spectrometry
Author(s) -
Hunsucker Steve W.,
Watson R. Craig,
Tissue Brian M.
Publication year - 2001
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.377
Subject(s) - chemistry , mass spectrometry , matrix assisted laser desorption electrospray ionization , characterization (materials science) , ambient ionization , desorption , sample preparation in mass spectrometry , ionization , matrix (chemical analysis) , soft laser desorption , protein mass spectrometry , matrix assisted laser desorption/ionization , analytical chemistry (journal) , chromatography , electrospray ionization , chemical ionization , organic chemistry , ion , nanotechnology , adsorption , materials science
We report the direct laser desorption/ionization (LDI) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric (MALDI‐TOFMS) analysis of four inorganic coordination complexes: monometallic [Ir(dpp) 2 Cl 2 ](PF 6 ), homonuclear trimetallic {[(bpy) 2 Ru(dpp)] 2 RuCl 2 }‐ (PF 6 ) 4 , and heteronuclear [(tpy)Ru(tpp)Ru(tpp)RhCl 3 ](PF 6 ) 4 and {[(bpy) 2 Ru(dpp)] 2 IrCl 2 }(PF 6 ) 5 (dpp = 2,3‐ bis ‐(2′‐pyridyl)pyrazine, bpy = 2,2′‐bipyridine, tpy = 2,2′,6′,2″‐terpyradine, tpp = 2,3,5,6,‐ tetrakis ‐(2′‐pyridyl)pyrazine). Spectral intensities and fragmentation patterns are compared and evaluated for instrument parameters, matrix selection, and matrix‐to‐analyte ratio. Direct LDI and MALDI mass spectra of the monometallic complex showed the same ion peaks and differed only in the relative peak intensities. Direct LDI of the trimetallic complexes produced only low‐mass fragments containing one metal at most. MALDI spectra of the trimetallic complexes exhibited little fragmentation in the high‐mass region (>1500 Da) and less fragmentation in the low‐mass region compared to direct LDI. Significant fragments of the molecules were detected and identified, including ligand fragments, intermediate‐mass fragments such as [Ru(tpy)] + , and molecular ions with varying degrees of PF 6 − loss ([M − n(PF 6 )] + , where n = 1–3). A correlation exists between the solution‐phase electrochemistry and the observed [M − n(PF 6 )] + series of peaks for the trimetallic complexes. Proper matrix selection for MALDI analysis was vital, as was an appropriate matrix‐to‐analyte ratio. The results demonstrate the applicability of MALDI‐TOFMS for the structural characterization of labile inorganic coordination complexes. Copyright © 2001 John Wiley & Sons, Ltd.