Cluster cations

The stmcture of the last 3 cluster cations are shown in Fig. 13.27. In discussing the... 

Other less-symmetrical coordination geometries for Se and Te occur in the /t,-Se2 and /t-Te2 complexes and the polyatomic cluster cations Seio and Tee" " ", as mentioned below. 

Figure 16.7 Structures of the hetcroatomic cluster cations (a) and (b) (TeiSe ]- .

Abstract Molecular spectroscopy is one of the most important means to characterize the various species in solid, hquid and gaseous elemental sulfur. In this chapter the vibrational, UV-Vis and mass spectra of sulfur molecules with between 2 and 20 atoms are critically reviewed together with the spectra of liquid sulfur and of solid allotropes including polymeric and high-pressure phases. In particular, low temperature Raman spectroscopy is a suitable technique to identify single species in mixtures. In mass spectra cluster cations with up to 56 atoms have been observed but fragmentation processes cause serious difficulties. The UV-Vis spectra of S4 are reassigned. The modern XANES spectroscopy has just started to be applied to sulfur allotropes and other sulfur compounds. 

In the preparation of Mo/HUSY, the cluster 1 amounting to 2.5 wt% (as molybdenum metal) of HUSY was added to the suspension of HUSY 92% of the molybdenum was loaded onto HUSY. The Cl/Mo ratio of Mo/HUSY was found to be 0.34, suggesting that in ion exchange the cluster 1 acted as a trivalent cation on the average. These findings indicate that the protons in HUSY are less exchangeable by the cluster cation than the Na cations in NaY. 

Gilb, S., Weis, P., Furche, F., Ahlrichs, R. and Kappes, M.M. (2002) Structures of small gold cluster cations (Au u< 14) Ion mobility measurements versus density functional calculations. Journal of Chemical Physics, 116, 4094—4101. 

In the reaction with BC13 or BBr3 in toluene as solvent, ionic compounds of type 51 were isolated as the main products together with the arachno-clusters 50 (X = C1, Br) and the compounds Me5C5BX2 as byproducts (Scheme 13). The nido cluster cation in 51 is identical with that in compound 48. 

The most stable cluster consists of an aggregation of four cation vacancies in a tetrahedral geometry surrounding an Fe3+ ion, called a 4 1 cluster. Cations in the sodium chloride structure normally occupy octahedral sites in which each metal is coordinated to six nonmetal atoms. The central Fe3+ ion in the 4 1 cluster is displaced into a normally unoccupied tetrahedral site in which the cation is coordinated to four oxygen ions. Because tetrahedral sites in the sodium chloride structure are normally empty, the Fe3+ is in an interstitial site. Equation (4.1) can now be written correctly as... 

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. 

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

Cluster Cations Source0 Apparatus Reactant Initial Products References... 

The reactions of small cluster cations of copper and silver, Cu and Ag (n = 1-5), with methanol, ethanol, the two isomers of propanol, and the four isomers of butanol have been studied in a FT-ICR mass spectrometer (200). The ions were produced by FAB and exited through a small hole that aided the clustering process. Once in the cell, the ions were collisionally cooled with argon and allowed to react with the alcohols (3-100 x 10 6 Pa) for periods up to 60 s. The Cu4 ion was produced but was of insufficient abundance for reactivity studies. 

The Cu+ ion and the copper cluster cations were more reactive than the similar silver cations. Methanol was unreactive to Cu and Ag (n = 1-5). Ethanol was unreactive to CU5 and Ag+ (n = 3-5). The general reactions are shown as equations with examples given after the equation (see Eqs. 44-48). 

In contrast to the addition of only one benzene molecule to even large niobium cluster anions, small niobium cluster anions react by the addition of up to 5 N2 molecules and up to 15 CO molecules (229). The reactions of the niobium cluster anions Nb (n = 2-7) were qualitatively similar to the reactions of the cluster cations and in both cases CO was more reactive than N2. The rates of reaction generally increased with increasing size of the cluster but in many cases extensive fragmentation of the clusters was observed. 

Gas-phase metal oxide cluster cations have become increasingly interesting because of the possibility that a controlled reaction of size selected clusters might shed some light on condensed-phase catalysts. The possibility of producing small clusters in the condensed phase from deposition of gas-phase clusters has also been a driving force in the study of the reactivity of gas-phase ions. 

The reactions of the vanadium oxide cluster cations with CCI4 were of three types (248). The small cluster ions reacted by transfer of a chloride ion. The larger clusters starting with the V4OJ+ series reacted by the addition of a chlorine atom to the cluster or the loss of one oxygen atom and the addition of two chlorine atoms. 

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