Characterization of o-phenanthroline and 2,2'-bipyridine complexes by laser mass spectrometry

Abstract

A series of o-phenanthroline (o-phen) and 2,2'-bipyridine (bpy) metal complexes has been studied by using laser mass spectrometry (LMS). The molecular caton is observed in the positive ion spectra for the tetracoordinated complexes (Ag(L)/sub 2/)NO/sub 3/,(Cu-(L)/sub 2/)/sub 2/SO/sub 4/.5H/sub 2/O, (Cu(L)/sub 2/)SO/sub 4/, and (Tl(L)/sub 2/)(ClO/sub 4/), where L = bpy or o-phen. Structurally significant fragment ions (ML/sub 2//sup +/, ML/sup +/, M/sup +/, LH/sup +/) are also observed. The hexacoordinate complexes (M(L)/sub 3/)Cl/sub 2/ and (Fe(L)/sub 3/)(ClO/sub 4/)/sub 2/, where L = bpy or o-phen and M = Ni, Co, or Ru, show molecular cations in the positive ion spectra; (Mn(bpy)/sub 3/)Br/sub 2/ does not. Generally, fragment ions such as ML/sub 3//sup +/, ML/sub 2/X/sup +/, ML/sub 2/..mu.., MLX/sup +/, ML/sup +/, and (L + H)/sup +/ are observed, where X = halogen. Complexes such as (M(o-phen)/sub 2/(H/sub 2/O)/sub 4/)(ClO/sub 4/)/sub 2/.2o-phen, where M = Ba or Pb, show ions having four ligands, e.g. ML/sub 4/ClO/sub 4//sup +/. The effect of anion on the fragmentation pattern of transition-metal complexes was studied with (Ni(bpy)/sub 3/)X/sub 2/ where X = Cl/sup -/, Br/sup -/, I/sup -/, ClO/sub 4//sup -/, or SCN/sup -/. Molecular cations were observed for all nickel complexes. Themore » fragmentation patterns were similar for halide analogues. Ions arising from ion-molecule reactions from the dissociated products of ClO/sub 4//sup -/ and CNS/sup -/ are observed. The negative ion LMS spectra of all complexes provide information about the anion and the formal oxidation state of the central metal atom. 32 references, 4 figures, 2 tables.« less