LIQUID MATRIX INDUCED PROCESSES IN FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY OF POLYAZACROWN TRANSITION-METAL COMPLEXES

A FAB-MS study of several macrocyclic divalent (Ni(II), Cu(II), Ag(II) ) and trivalent (Cr(III), Mn(III), Fe(III), Co(III), Ni(III), Rh(III)) transition metal (M) polyamine complexes based on 1,4,7-triazacyclono nane ([9]ane-N3) (L1) and 1,4,8,11-tetraazacyclotetradecane ([14]ane-N 4) (L2) has been undertaken, using glycerol, thioglycerol and m-nitrob enzyl alcohol (m-NBA) as matrices. Removal of one neutralizing anion f rom the complexes ([9]ane-N3)2M(n+)nX- and [([14]ane-N4)M(n+)(n-1)X-]Y - produces cations [([9]ane-N3)2M(n+)(n-1)X-]+ and [([14]ane-N4)M(n+)( n-1)X-]+ that, in most of the cases, represent the highest mass ion in the spectra. Subsequent matrix assisted one-electron reduction(s) and concomitant anion loss(es) produce singly charged species [([9]ane-N3 )2M(n-1)+(n-2)X-]+ and [([14]ane-N4)M(-1)+(n-2)X-]+, with the metal in a lower oxidation state, which undergo successive oxidative dehydroge nations.