No abstract

A series of new “magic number” metal oxide clusters are described for the group V metals antimony and bismuth. Specific nonstatistical stoichiometries of M x O y cation and anion clusters are formed preferentially in the gas phase when oxidized metal is vaporized or when metal is vaporized and combined with gas phase oxygen (e.g., Bi7O10 +, Bi9O14 +). Essentially the same stoichiometries are seen for antimony and bismuth analogues. The species produced in cluster growth are also produced preferentially by photodissociation of larger clusters. Localized covalent bonding schemes are suggested for these clusters, and polyhedral cage structures are proposed. The stoichiometries observed require a 3+ metal oxidation state in the small clusters, which shifts over to one or more 5+ metal atoms in larger clusters.

Ca + – C 2 H 2 is produced in a molecular beam and studied with mass-selected photodissociation spectroscopy. A spectrum with sharp vibrational and rotational structure is measured near the Ca+ (2P←2S) transition. Ca+–C2H2 has a π-complex structure with a Ca+–C2H2 bond distance of r0″=2.80±0.20 Å, a vibrational frequency (Ca+–C2H2 stretch) of ΔG1/2″=169 cm−1, and a dissociation energy of D0″=18.6±5.0 kcal/mol. This is the first spectroscopic determination of these properties for an isolated metal cation π complex.