Anionic metal clusters

Leopold D G, Ho J and Lineberger W C 1987 Photoelectron spectroscopy of mass-selected metal cluster anions. I. Cuji, n = 1 -10 J. Chem. Phys. 86 1715... 

Berg C, Beyer M, Achatz U, Joes S, Niedner-Schatteburg G and Bondybey V 1998 Effect of charge upon metal cluster chemistry reactions of Nb and Rh anions and cations with benzene J. Chem. Rhys. 108 5398... 

As a result of the systematic application of coordination-chemistry principles, dozens of previously unsuspected stnicture types have been synthesized in which polyhedral boranes or their anions can be considered to act as ligands which donate electron density to metal centres, thereby forming novel metallaboranc elusters, ". Some 40 metals have been found to act as acceptors in this way (see also p. 178). The ideas have been particularly helpful m emphasizing the close interconnection between several previously separated branches of chemistry, notably boron hydride clu.ster chemistry, metallaboranc and metallacarbaborane chemistry (pp. 189-95). organometallic chemistry and metal-metal cluster chemistry. All are now seen to be parts of a coherent whole. 

The mles can readily be extended to isoelectronic anions and carbaboranes (BH=B =C) and also to metalloboranes (p. 174), metallocarbaboranes (p. 194) and even to metal clusters themselves, though they become less reliable the further one moves away from boron in atomic size, ionization energy, electronegativity, etc. 

Many novel cluster compounds have now been prepared in this way, including mixed metal clusters. Further routes involve the oxidative fusion of dicarbon metallacarborane anions to give dimetal tetracarbon clusters such as (103) and (104) O (jjg insertion of isonitriles into inetallaborane clusters to give monocarbon meiallacarboranes such as (105) and the reaction of small ii/t/o-carboranes with alane adducts such as Et3NAlH3 to give the commo species (106) ... 

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

G. Metal Cluster and Metal Oxide Anion Reactions.226... 

Each of the examples (5.1)—(5.4) illustrates the linking of molecules into supramolecular species that constitute new units of liquid, gaseous, or solid phases. Other provocative examples of supramolecular aggregation include the al-lotropic phases of sulfur (composed of a variety of linear and cyclic polymeric chains)9 and the remarkable Zintl salts (with anions composed of variable metal clusters).10... 

There are several kinds of cluster ions, both cations and anions, observed in mass spectrometers. There are bare metal cluster cations and anions, binary clusters cations and anions M Em (where E is an element such as O or S), and other clusters involving ligands and metals. In this section, the bare metal cluster cations Mj and anions M will be discussed separately followed by the binary cluster cations M E+, then binary cluster anions M E , and finally other cluster systems having more than one metal atom. 

Many of the metal cluster anions have been produced by cathode discharge in He doped with Ar and studied in a flow tube reactor. A few clusters have been prepared by laser vaporization using a supersonic cluster beam source and the reac-... 

Gas-Phase Metal Cluster Anions of Transition Metals, Production, and Gas-Phase Reactions... 

Platinum oxide cluster anions [Pt O]- and [PtM02] have been prepared by the reaction of the bare metal cluster anions [Pt ]- with N20 and 02, respectively (255). These platinum oxide cluster anions will oxidize CO to C02 and produce [PtJ, which can be reoxidized by N20 or 02. Thus a cyclic catalytic system for the oxidation of CO by N20 or 02 is produced. 

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