Characterization of metal complexes of 1,10-phenanthroline, 2,2′-bipyridine, and their derivatives by fast atom bombardment mass spectrometry

Abstract

A series of 1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (5-NO2-phen), 2,9-dimethyl- 1,10-phenanthroline (dmp), 2,2′-bipyridine (bpy), and 4,4′-dimethy-2,2′-bipyridine (dmb) metal complexes has been characterized using fast atom bombardment mass spectrometry (FAB MS). Intact cations are observed in the positive ion FAB mass spectra of all tetracoordinated complexes, [Ag(L)2]NO3, [Cu(L)2]2 SO4•5H2O, [Cu(L)2]SO4, and [Tl(L)2](ClO4), where L=bpy, phen, or dmp. Structurally significant fragment ions (ML2+, ML+, M+, and (L+H)+, where M+=metal ion) are also observed. Species such as Ag[Ag(L)2]NO3+, where L=bpy or phen, and Tl[Tl(phen)2](ClO4)+ are also seen. The hexacoordinate complexes, [Co(phen)3]Cl2, [Ru(bpy)Cl2], [Fe(phen)2(CN)2], [Fe(L)3](ClO4), where L=5-NO2-phen, dmb, or bpy, and [Fe(L)3]SO4, where L=bpy or phen, show intact cations in the positive ion spectra; [Ni(bpy)3]X2, where X=Cl−,Br−, NO3−, ClO4−, SCN−, and tartrate2−, and [Co(bpy)3](ClO4) do not. Generally, fragment ions such as ML3+, ML2X+, ML2+, MLX+, and (L+H)+ are observed, where X=singly charged intact anion or HSO4−. Comparison of FAB results with those of laser mass spectrometry (LMS) show that they are comparable, through reduction processes are more important for FAB. LMS always gave the intact cation while FAB was not consistent. Keywords: FAB mass spectrometry, phenanthroline complexes, bipyridine complexes, laser desorption mass spectrometry.