Clusters cationic

Figure 13.27 The structures of cationic clusters of Bim"+. The dimensions cited for Bi9 + were obtained from an X-ray study on [(Bi9 +)(Bi )(HfCl6 )3] the corresponding average distances for Bi9 + in BiCli 1 7 i.e. [(Bi9 +)2(BiCl5 )4(Bi2Cl8 )] are 310, 320 and 380pm respectively. The square antiprismatic structure of Big " was established by an X-ray study of Bi8[AlCl4]2. ...

The [Au7(PPh,)7] cation cluster is prepared by evaporating 4 mmol Au onto a solution of 6 mmol PPh3 in 300 mL toluene. The yield is 20-30% (based on Au). 

FIGURE 5.10 (a) Scientific representation of the three-phase structure of a dry ionomer, consisting of cation clusters, lamellae, and disordered regions. (From Cowie, J.M.G., Polymer Chemistry and Physics of Modern Materials, Intertext, London, 1973.)... 

Simple cations are unknown within Group 16 (besides Po), but several highly colored polyatomic cations (cationic clusters), like S " ", Sg, Se, SCg, Te, and Teg" ", have been isolated in non-aqueous media [15]. Some mixed chalcogen cationic clusters have also been reported. These are all unstable in water. 

DF calculations were carried out on CO complexes of small neutral, cationic, and anionic gold clusters Au with n= 1-6. The -coordination mode (terminal C-coordination) was found to be the most favorable one irrespective of the charge of the cluster, and cluster planarity is more stable for the bare clusters and their carbonyls. As expected, adsorption energies are greatest for the cationic clusters, and decrease with size. Instead, the adsorption energies of... 

The reactions of some transition metal cluster ions have been described in a review by Parent and Anderson (201). The review covered reactions reported up to 1992 and so the reactions reported here are generally later than 1992. A recent review by Knickelbein (202) discusses the reactions of cation clusters of iron, cobalt, nickel, copper, silver, niobium, and tungsten with small molecules such as H2 and D2. Some of the reactions in Knickelbein s review are included in the following tables of reactions (Tables IV and V). Table IV gives examples of the reactions of transition metal cluster ions and includes the vaporization source, experimental apparatus, the reactants, and the observed product ions. A few examples from these tables will be selected for further discussion. 

Concise Chemical Bonding Analysis of B3 B 3 Cationic Clusters... 

There are only a few examples of cationic clusters, which is in keeping with the postulated electron-sink effect of the system of metal-metal bonds. This hypothesis is supported by examination of some properties of the clusters Co3(CO)9(/i3-CR) as reported previously207 209. ... 

Up till now anionic mercury clusters have only existed as clearly separable structural units in alloys obtained by highly exothermic reactions between electropositive metals (preferably alkali and alkaline earth metals) and mercury. There is, however, weak evidence that some of the clusters might exist as intermediate species in liquid ammonia [13]. Cationic mercury clusters on the other hand are exclusively synthesized and crystallized by solvent reactions. Figure 2.4-2 gives an overview of the shapes of small monomeric and oligomeric anionic mercury clusters found in alkali and alkaline earth amalgams in comparison with a selection of cationic clusters. For isolated single mercury anions and extended network structures of mercury see Section 2.4.2.4. 

Controlled methanolysis of FeCh in the presence of /3-diketones and of LiOMe or NaOMe in anhydrous methanol gives cyclic hexanuclear yellowish-red cationic clusters [MFeg(OMe)i2L6] (LH = e.g., PhCFl2COCH2COCH2Ph M = Li, Na), in which the Feg(OMe)i2 unit accommodates the alkali metal cation, both in the solid state and in solution. 

There are no well-characterized polymeric bismuth catenates, although a black ether-insoluble substance, described as (PhBi)x, results from the reduction of phenylbismuth halides with LiAlH4.200 A polymeric bismuthine is thought to result from the decomposition of l,T-bibismolane.201 To date, bismuth catenation is limited to Bi2 in the case of free molecules and to some complex anionic and cationic clusters. 

Photo-excited SO2 and SO2 clusters have been observed to undergo a number of excited state and ion-state processes. Ion-state studies have, for example, identified the energy threshold of the ion-state oxygen loss channel of the SO2 monomer and dimer [1], Additionally, studies investigating the metastable decay process of SO2 clusters and mixed S02-water clusters have identified the dissociation pathways and the nature of the charged core of these cationic clusters [2]. The dynamics of oxygen loss of SO2 and SO2 clusters following excitation to the C (2 A ) state, which couples to a repulsive state, have also been studied to determine the influence of the cluster environment on the dissociation process [3]. 

Gas products from the alkylation of acetonitrile were regularly analysed using the same column as used for the side-chain alkylation of toluene. Liquid products were also collected every 30 minutes in an acetone-ice bath, but were analysed using a Porapak Q column at 150-180 °C with a helium carrier gas flow rate of 30 ml/min. To investigate the effect of carbonated catalysts, especially that with the excess cesium cation "clusters", carbon dioxide was introduced to the fresh CsNaX-CsOH at the reaction temperature, 350 °C, for 30 minutes before the alkylation of acetonitrile was carried out in a flow of helium. The cesium clusters of treated catalysts were presumed to be fully carbonated (CS2CO3) clusters and the activity of this catalyst was compared with the untreated CsNaX-CsOH. 

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