Electrospray ionization mass spectrometric study of 1,3,4-oxadiazole-copper complexes

The complexes of 2,5-disubstituted-1,3,4-oxadiazoles, namely 2,5-diphenyl-1,3,4-oxadiazole (1), 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (2) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (3), with copper cation were studied by electrospray ionization mass spectrometry (ESI-MS). The ability of the compounds studied to form complexes with copper (under the ESI conditions) can be ordered as 2 > 1 > 3. The compounds studied tend to form both 1: 1 and 2: 1 chelate complexes with both copper(II) and copper(l). The complexes with copper(I) are formed in the ESI process. The influence of solvent polarity, solution flow-rate, counter ions 2(Cl-, NO3- CH3COO-, SO42-, acetylacetonates) on the type of the ions observed was studied. Copyright (C) 2004 John Wiley Sons, Ltd.