Electrospray ionization mass spectrometric study of Cu(I) and Cu(II) bipyridine complexes employed in atom transfer radical polymerization

We report an electrospray ionization mass spectrometric study of Cu(I) and Cu(II) bipyridine complexes employed in atom transfer radical polymerization. Mass spectra of Cu(I)Br complexed with 2 equiv. of 4,4'-di(5-nonyl)-2,2'-bipyridine (dNbpy) in toluene, methyl acrylate or styrene showed the presence of Cu(I)(dNbpy)(2)](+) cation and Cu(I)Br(2)](-) anion. For the Cu(II)Br(2)/2dNbpy system, Cu(II)(dNbpy)(2)Br](+), Cu(II)(dNbpy)Br](+), Cu(I)Br(2)](-), Cu(II)Br(3)](-) and Cu(II)(dNbpy)Br(3)](-) species were observed. In addition, for mixed Cu(I)Br/2dNbpy and Cu(II)Br(2)/2dNbpy systems, the negative ion mode showed only the presence of Cu(I)Br(2)](-) anions, which are potentially formed through halogen exchange between Cu(II)Br(3)](-) and Cu(I)(dNbpy)(2)](+). Copyright 2000 John Wiley & Sons, Ltd.