Magic numbers in Aln+(H2O)1 cluster cations

We report the observation of magic numbers in the mass spectrum of Aln+(H2O)1. These cluster cations were produced in a laser vaporization source in the presence of trace amounts of water. The most prominent magic number species observed was Al13+(H2O)1. We attribute its pronounced intensity to its enhanced stability resulting from the formation of a coordinate bond between the Al13+ moiety and the oxygen atom of water. The sharing of an oxygen lone electron pair with Al13+ lends to it some of the character of the 40-valence electron, closed shell Al13− magic cluster.