Electronic spectroscopy and photodissociation dynamics of Co 2 1 – methanol clusters : Co 2 1 ( CH 3 OH ) n ( n = 4 – 7 )

Solvated cluster ions Co(CH3OH)n (n 1⁄4 4–7) have been produced by electrospray and studied using photofragment spectroscopy. There are notable differences between the photodissociation spectra of these complexes and the analogous water complexes. Co(CH3OH)6 absorbs significantly more strongly than Co(H2O)6. The photodissociation spectra of Co (CH3OH)n (n 1⁄4 4, 5 and 6) are very similar, which suggests that they share the Co(CH3OH)4 chromophore, with additional solvent molecules in the second shell. In contrast, our earlier studies indicate that Co(H2O)6 is six coordinate, and its spectrum is significantly different from that of Co(H2O)4. The larger clusters Co (CH3OH)n (n 1⁄4 5–7) dissociate by simple loss of one or more solvent molecules. Larger clusters tend to lose more solvent molecules, especially at higher photon energies. As with the corresponding water cluster, Co(CH3OH)4 photodissociates by proton transfer through a salt-bridge intermediate. This is accompanied by a modest kinetic energy release of 170 kJ mol 1 and occurs with a lifetime of 145 ns.