Electrospray mass spectrometry characterization of ionic silver(I) and gold(I) complexes of the ligand L = 1-benzyl-2-imidazolyl-diphenylphosphine: Counterion influence in the ionization processes and crystal structure determination of [Ag2L3][CF3SO3]2

One of the most discussed and studied aspects of the silver(I) coordination complexes chemistry is the influence of the counterions in the solid state structures and in the ligand exchange reactions occurring in solution; this kind of chemistry is pretty rare in the gold(I) coordination derivatives. Some silver(I) and gold(I) complexes of the type L2M2X2 (where L is 1-benzyl-2-imidazolyl diphenylphosphine I, M = Ag, X = BF4II; X = NO3III, X = CF3SO3IV, X = BAr4V), L3M2X2 (M = Ag, X =NO3VI, X = BF4VII, X = BAr4VIII, X = CF3SO3IX), LAuCl (X), L2Au2X2 (X = BF4, XI) and L2AuBF4 (XII) have been synthesized. The solid state structures of the compounds I, II, III, and X have been already reported, that of XII will be published elsewhere, whilst the unprecedented structure of IX is discussed here. From the analysis of the structures, it can be argued that in the silver(I) complexes the counterions deeply affect the structure by strongly interacting with the metal centres. Here we report, in addition to the discussion of the structure of IX, the study of these complexes by the ESI mass spectrometry with the target of both studying the counterion effect in the ionization process, and to characterize the above described complexes by this new soft mass spectrometry technique.