Experiment proves that the ions [Cu(H2O)(n)](2+) (n=1,2) are stable in thegas phase

Electrospray ionization has been used to create the cupric ion hydrate [Cu( H2O)(4)](2+) Collisional. activation and dissociation of this ion in a trip le sector electrostatic mass spectrometer leads to the formation of the dou bly charged ions [Cu(H2O)(3)](2+), [Cu(H2O)](2+) and [Cu(H2O)](2+). The obs ervation of the latter two ions vindicates the results of published theoret ical calculations [El-Nahas et at., Chem. Phys. Lett. 318 (2000) 333], whic h predicted the stability of the cupric ion solvated by one or two water mo lecules and refutes the belief of Stace et al. [Chem. Phys. Lett. 329 (2000 ) 173] that their pick-up experiments prove that [Cu(H2O)(3)](2+) is the lo west stable gas-phase hydrate of the cupric ion. (C) 2001 Published by Else vier Science B.V.