Abstract
The effect of solvent and counter ion on the complexes of 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (1) with Fe+2 and Fe+3 has been studied by electrospray ionization mass spectrometry (ESI/MS). As expected, upon ESI conditions the metal reduction proceeds, but it can be deduced that complexes with Fe+2 are favored over those with Fe+3. When methanol is used as solvent, the formation of complexes of stoichiometry 2: 1 and 1: 1 with counter ion attached (monovalent anion) is favored, for example, [12 + FeCl]+ ion. The use of methanol/water (1 / 1) as solvent favors the formation of complexes of stoichiometry 2:1 and 3: 1, namely doubly charged [12+Fe]+2 and [13+Fe]+2 ions. The complexes containing anion of oxidative properties (ClO4−, NO3−), when the higher cone voltage is applied, yield unusual species [1 n +FeO m ]+ (n = 1, 2; m = 1, 2). The use of divalent counter ion (SO4−2) resulted in formation of complexes containing two iron cations, namely [1 n + Fe2SO4]+2 (n = 2, 3, 4) ions. These ions can be regarded as Fe-1 complexes bridged by a sulfate anion.
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