Collision-induced dissociation of MCl+ adducts (M = Mg, Mn, Zn, Co, Ni andCu) and Cu+ and Ag+ adducts of dithioalkyl ketene acetals

Electrospray ionization mass spectra of equimolar solutions of dithioalkyl ketene acetals I and 2 and metal chlorides (MgCl2, MnCl2, ZnCl2, CoCl2, NiC l2 and CuCl2) produced abundant ligated metal ion adducts [1 + MCl](+) and [2 + MCl](+). In addition, CuCl2 also gave rise to Cut adducts. The ligated metal ion adducts upon collision-induced dissociation (CID) showed charact eristic fragmentation pathways reflecting the favoured site of coordination . The results show that MgCl+ prefers oxygen over sulfur, whereas the rever se is true for ZnCl+ adducts, exemplified by the preferred fragmentation of [1 + MgCl](+) as elimination of MgCl(OH), while that of [1 + ZnCl](+) is e xpulsion of ZnCl(SCH3). Co and Ni chloride adducts tend to give stable meta l coordinated species. Cleavage of the dithiolane ring followed by eliminat ion of C2H4S is the preferred pathway during the CID of [2 + MCl](+) adduct s. The CuCl+ adducts of 1 and 2 showed reduction of Cu-(I) to Cu-(0) result ing in the M+ ions of I and 2. Abstraction of CH3 resulting in elimination of CuCH3 was observed during CID of Cu+ adducts of 1 and 2. A comparative s tudy of the corresponding Ag+ adducts revealed a similar behaviour. Copyrig ht (C) 2001 John Wiley & Sons, Ltd.