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Two techniques are applied and the results compared both in the plasma core and in the edge region of "Thorello" to estimate electron temperature fluctuations. The first method is a fast-sweep Langmuir probe: it is a new apparatus based on a dual channel circuit that compensates for stray capacitance and permits sweep speeds up to 400 kHz, so that we can investigate the electrostatic turbulence with good temporal resolution. The second technique is the conventional triple probe: this method allows us to measure density, temperature, and floating potential as a function of time. The fast-sweep Langmuir probe provides a more reliable electron temperature fluctuations and these measurements are essential for a correct interpretation of density and potential fluctuations.

The hydrolysis of the [NI6(CO) 12]2- anion under buffered conditions results in the synthesis of the interstitial hydride derivatives [Ni12(C0)21H2]2- and [Nil2(C0)21H]3-. The two compounds are related by an easily reversible protonation-deprotonation equilibrium. In contrast, deprotonation of [Ni12(C0)21H]3- to the corresponding [Nil2(C0)21]4- tetraanion is possible only under severe conditions. The tetraanion has been obtained as a byproduct of the synthesis of [Ni6(Co)12]2- by reduction of Ni(C0)4 in KOH-saturated methanolic solution.

The synthesis and the structure of the novel trianion [fe3Rh3(CO)17]3- is reported; the metal framework of this 88 valence electron bimetallic cluster is unusual, and consists of an Fe2Rh3 trigonal bipyramid with iron and rhodium atoms in apical sites and a dangling Fe atom attached to the apical Rh.

The dark brown [Ir3Ni6(m-CO)6(m3-CO)2(CO)9]3- trianion has been obtained by redox condensation between [Ni(CO)4] and [Ir(CO)4]-. This new mixed-metal cluster is rapidly degraded, at room temperature and atmospheric pressure, by carbon monoxide to form the [Ni(CO)4] and [Ir(CO)4]- parent mononuclear compounds. The metal framework consists of a face-sharing bioctahedron, with the three iridium atoms located in the inner triangle.

In the title compound two C‐atoms are located in the cavity of a cluster. The CċC distance in very short—only 1.49 Å (for comparison: CC single bond 1.54 Å)—but, as deduced from a consideration of the number of cluster valence electrons, a delocalized CC interaction is more probable than a localized one. (Figure Presented.) Copyright © 1984 by Verlag Chemie, GmbH, Germany

The synthesis and properties of the new dicarbidocarbonyl bimetallic clusters [Co3Ni7(CO)16C2]2- and [Co3Ni7(co)15C2]3- are described. Anion I is paramagnetic, and has a metal frame based on a 3,4,3-C2h stack of metal atoms. The resulting deca-vertces metal polyhedron encapsulates a c2 fragment showing a short C-C interatomic separation of 1.48 Å

The syntheses and interconversions of mixed iron-rhodium carbonyl clusters are described; a combination of X-ray analysis and multinuclear n.m.r. measurements allowed the structural characterisation of [FeRh4(CO)15]2-, [FeRh5(CO)16]-, and [Fe2Rh4(C0)16]2- which can all be obtained from the unstable cluster, [Fe2Rh(CO)x]

Reaction of [Co3(CO)9CCl] with [Ni6(CO)12]2- results in a complicated mixture of mixed Co-Ni carbide carbonyl clusters, among which the [Co3Ni9C(CO)21]3- trianion has been isolated in a pure crystalline state and fully characterized by X-ray crystallography. The metal framework of this compound is unprecedented in cluster geometries and may be described as a square antiprism of metal atoms tetra-capped on two alternate pairs of adjacent triangular faces. Despite the presence of a caged carbon atom in the square-antiprismatic cavity, the compound is readily degraded by carbon monoxide (25 "C, 1 atm) mainly to a mixture of [Co(CO)4]- and [Ni(CO)4]. Corresponding degradation of the cluster under a mixture of carbon monoxide and hydrogen yields, in addition, trace amounts of organics, mainly C1 and C2 hydrocarbons, probably derived from the carbide atom.

The synthesis and chemical behaviour of the new iron-rhodium anionic carbonyl clusters [Fe2Rh(CO)x]- ( x = 10 or 11) [FeRh4CO)15]2-, [Fe2Rh4(C0)16]2-, and [FeRh5(CO)16]- are reported. Low-temperature multinuclear n.m.r. studies (l3C, 13C-(103Rh}, and l03Rh) on the penta- and hexa-nuclear clusters allow their structures in solution to be unambiguously established and their fluxional behaviour has been investigated through variable-temperature measurements. None shows rearrangement of the metal polyhedron.

The anion [HFe3Rh(CO)12]2− was obtained by reaction of [HFe(CO)4]− with Rh2(CO)4Cl2 in refluxing THF. Its solid state structure consists of a tetrahedron of metal atoms with three edge-bridging and nine terminal carbonyl groups. The hydridic ligand bridges a face containing the rhodium atom.