Consecutive fragmentations of the cubane-like zinc cluster [CH3Zn(O-i-C3H7)](4) upon electron ionization

The sequential dissociations of the tetranuclear zinc cluster-ion [(CH3)(3)Zn-4(O-i-C3H7)(4)](+) obtained by dissociative electron ionization of neutral [(CH3) Zn(O-i-C3H7)](4) are investigated by tandem mass spectrometry. After initial loss of a neutral (CH3) Zn(O-i-C3H7) unit to afford [(CH3)(2)Zn-3(O-i-C3H7)(3)](+), hydrogen migration leads to the expulsion of neutral acetone concomitant with [(CH3)(2)Zn-3(O-i-C3H7)(2)(H)](+) as ionic fragment. Unimolecular dissociation of the latter gives rise to [(CH3)(2)Zn-2(O-i-C3H7)](+) and neutral HZn(O-i-C3H7). As demonstrated by collisional ionization of the neutral product, in the fragmentation of the dinuclear cluster [(CH3)(2)Zn-2(O-i-C3H7)](+) neutral CH3ZnH is formed, rather than the more stable fragments Zn + CH4. From the resulting mononuclear species CH3Zn(OC(CH3)(2))(+) acetone is eliminated to afford CH3Zn+ as a quasi-terminal fragment ion.