Clusters cubic

Figure 1. Structure of the face-centered cubic cluster [(Me3tacn)gCrgNi6(CN)24] Black, crosshatched, shaded, and white spheres represent Cr, Ni, C, and N atoms, respectively H atoms are omitted for clarity.

One type of this class of compound exists, namely, the cubic cluster species [E4Co4(CO)l2] (150, E = Sb 151, E = Bi) (see Fig. 42). The antimony derivative was reported by Dahl (145) as resulting from a high-temperature and... 

Exercise 5.4. Consider the two limiting cubane cluster geometries shown below. The first has a fully bonded metal tetrahedron with four triply bridging ligands whereas the latter has no M-M bonds and is a three-connect M4E4 cubic cluster. Calculate the expected eve and sep cluster counts of each and thereby illustrate the limits on electron count for this cluster type. 

Cubic clusters on the molecular-cluster-solid-state borderline... 

Answer. The metal count is 59 (9 x 9 (Co) — 11x2 ([Se]2—) = 59). This is 25 more than for [Mo9Sen]2 Indeed a large gamut of electron counts is possible for these condensed octahedral clusters, either molecular or part of extended solids. They are nice examples of compounds which can display variable electron count with constant shape. This situation is somewhat reminiscent of the transition-metal elements which exhibit a metallic d band which is gradually filled as we go from the left to the right of the periodic table without substantial change in their structure. Also review the discussion of cubic clusters in Section 5.2.5. 

MoW284(H20)9] +. Electrochemical studies of these pentacationic mixed metal cubic clusters revealed two reversible redox processes corresponding to a one-electron reduction and a one-electron oxidation. 

Strictly speaking the densities of the electronic cloud on the sites of the atomic nuclei, the so-called on-site density, need not be different for different components of a degenerate wave function. A simple counter-example is a orbital level in a cubic cluster. Let a,) denote a a-type atomic orbital on a given site i. The symmetry adapted linear combinations (SALC s) of these basis orbitals are given by (see Fig. 1) ... 

Perovskite BaTi03 shows phase transitions such as Cubic Tetragonal Orthorombic Trigonal, when it is cooled from high temperature. BaTi03 crystal exists in the cubic state above 120 °C and in the tetragonal state below 120 C. So, the DV-Xa calculations were carried out for both the cubic clusters and the tetragonal clusters, respectively. For the DV-Xa calculations... 

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