Linked clusters

A MOF constructed from rhodium paddlewheel clusters linked to porphyrinic ligands already discussed in Section 4.3.1.1 shows an interesting synergetic behavior when the porphyrinic rings are loaded with metals like Cu , Ni , or Pd . In the hydrogenation of olefins, the hydride species at the rhodium center is transferred to the coordinated olefin adsorbed on a metal ion in the center of the porphyrin ring to form an alkyl species, and next this alkyl species reacts with a hydride species activated at the rhodium center to form the alkane [81]. 

Typical surfaces observed in Ising model simulations are illustrated in Fig. 2. The size and extent of adatom and vacancy clusters increases with the temperature. Above a transition temperature (T. 62 for the surface illustrated), the clusters percolate. That is, some of the clusters link up to produce a connected network over the entire surface. Above Tj, crystal growth can proceed without two-dimensional nucleation, since large clusters are an inherent part of the interface structure. Finite growth rates are expected at arbitrarily small values of the supersaturation. 

Top two representations of the [Mo6C18]4+ cluster and the structure of the [Mo6C114]2- ion. Bottom array of Mo6Clg clusters linked via chlorine atoms to a layer in Mo6C112... 

The 22-vertex carborane C4B18H22 (COMC (1982) 5.4.2.6.7) was structurally characterized by X-ray crystallography and contains two nido-type 7,8-C2B9 clusters linked by three B-B bonds between B-B edges on their open faces.665 It is considered to be related to the neutral 7,8-C2B9Hi3 rather than the 7,8-C2B9Hi2 anion on the basis of NMR spectroscopic and structural comparisons.52,665... 

Figure 4.31. Crystal structure of the Chevrel phase Mo6PbS8. Portions of four rhombohedral unit cells with one common Pb atom (black) are shown. The bonding between different clusters is suggested by the Mo—S inter-cluster links.

The PET class has many samples that are very closely clustered (linked at a distance of 0.1). This can also be seen in the plot of the preprocessed data (Figure 4.20). 

FIGURE 35. Structure of trinuclear Ni clusters linked by diNC ligands. 

Reaction of Cul with bis(phenylthio)methane in acetonitrile in a 2 1 molar ratio gave air-stable colorless crystals of general formula [ Cu4(p,3-I)4 [ i-PhSCH2SPh j2] 9 (Scheme 8). Modification of the molar ratio—for example, a 1 1 or 1 2 molar ratio—had no influence on the composition of the resulting material and only compound 9 was formed.145 The crystal structure of 9 (Fig. 13) consists of cubane-like Cu4I4 clusters linked by bridging dithioether ligands to... 

For the sake of correctness, it is necessary to note that we disregarded such theoretically important concepts as the linked cluster (linked connected graph) theorem and the exclusion principle violating (EPV) diagrams. This is in accordance with our aim to maintain the practical nature of this review. The linked cluster theorem and EPV diagrams are of importance in the fourth and higher orders of the perturbation theory which, in our opinion, shall hardly be accessible to routine calculations in the foreseeable future. For detailed information on the linked cluster theorem and EPV diagrams see Refs.9,33,34,4a ... 

Poster 27. W. Takahara and F. Minami (Osaka University) Chemical Nature of Si-O Bonds in Silica-Based Clusters-Linking for Element Selection Rules in Biological System... 

The structure may be described as molybdate clusters linked through copper octahedra into one-dimensional chains which are in turn cross-linked by ethylene-diphosphonate subunits into a two-dimensional network. The (Cu(bpy)(Mo40i2) (H20)2 2+ substructure is shown in Figure 18b. 

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