Clustering types

P4) is closely similar with P-P distances of 216 pm (smaller than for P4 itself, 221pm). Indeed, a whole series of complexes has now been established with the same structure-motif and differing only in the number of valency electrons in the cluster some of these are summarized in Table 13.11. The number of valence electrons in all these complexes falls in the range 30-34 as predicted by R. Hoffmann and his colleagues.Many other cluster types incorporating differing numbers of Group 15 and transition metal atoms are now known and have been fully reviewed. ... 

The definitions of the cluster ligands of the [3Fe-4S] cluster and of the related structural features are quite useful to predict cluster types in other Fds of known sequence, as well as to determine the nature of the cluster coordinating atoms (and variability) and their control on the type and performances of the metal sites, in particular in terms of cluster stability, cluster interconversion capability, and acceptance of other metals at the cluster. 

Solid-state cluster chemistry is dominated by octahedral (M 5L8)L6 and (MsLi2)L units which are the focus of this paper. These two cluster types are different in the way the metal octahedral core is surrounded by the ligands. In (MsLg)L6-type clusters (Fig. 6.1a), typical for molybdenum and rhenium halides, chalcogenides, and chalcohalides, eight innei hgands (L ) cap the octahedron faces and six outer ligands (L ) are located in the apical positions [9]. For metals with a smaller number of valence electrons, the (M6L i2)L -type clusters... 

The outer ligands in M3Q4L9 (type-I) and M3Q7L6 (type-II) clusters can be easily replaced through nucleophilic substitution reactions. These reactions are discussed separately for each cluster type. 

Uptake, which was seen to be suppressed in the order Ru/Se > Ru/S > Ru black, in accordance with the ORR activity. It should be noted that unlike the cluster-type Ru i Se), and Ru/Se materials, surface modification of bulk polycrystalline Ru with Se did not lead to comparable enhancement of the ORR activity. 

Localization Cluster type Position of the Al atom Cluster composition... 

Cluster types. According to 1/1 AC structures, all three i-QCs types contain building blocks with local fivefold symmetry (Fig. 2). Obviously, a search for possible new QC/AC systems should look to precursors in which clusters with pseudoicosahedral symmetries are major structural motifs. 

The MSX1S cluster type as found in the oxides Zn2Mo308, LiZn2Mo308, and Zn3Mo308. ( See Table / for atom numbering scheme.)... 

Core extrusion studies—removal of the iron-sulfur cluster intact from the enzyme surroundings—have been carried out and the iron-cluster types in proteins identified through the process shown in equation 6.10.18 DMS0/H20 is the protein unfolding solvent for this process. By this method, Fe-protein and MoFe-protein metal-sulfur clusters have been removed from the holoenzyme for separate analysis by many instrumental techniques. 

R3Si709(0H)3], with group 13 metalorganics MR3 have been investigated in detail. In particular, reactions of alanes RxA1H3 x (x= 1-3) have been studied,624 yielding novel heterocyclic and cluster-type complexes. 

It is a well known fact that in light nuclei many states are of the cluster type, see [16]. States close to the threshold energy of break up into constituent clusters are precisely of the cluster type. For example it was found that the calculated second 0+ state in 12C, which corresponds to the observed second 0+ state located at 0.39 MeV above the 3a threshold energy, has a structure where individual a-clustcrs interact predominantly in relative S-waves. Thus it was concluded that the cluster state near = nEa with n = 3 and where Ea is the n-particlc binding energy has an a-particlc gas-like structure. 

The structural principle of alkali metal suboxides has been unique for many years. Early attempts to synthesize cluster-type subnitrides of Ba resulted in the only compound, Ba2N, that is isotypic with Ca2N. Beyond these, the Sr analogue Sr2N, and most recently Sr4N3 [34], have been characterized. 

An example of an edge-sharing cluster is [RuioC2(CO)24]2 (condensation of two octahedral clusters of the type [Ru6(CO)18]2-) another example may be the structure of the ion [Re4(CO)i6]2 which can be described as the edge-sharing condensation of two triangular structures of the neutral cluster type Os3(CO)i2. 

The main characteristic of cluster-type indices is that all bonds are connected to the common, central atom (star-type structure). The third-order cluster molecular connectivity index (3yc) is the first, simplest member of the cluster-type indices where three bonds are joined to the common central atom [102-104, 111-113,152-154,166,167,269]. The simplest chemical structure it refers to is the non-hydrogen part of ferf-butane. This index is then calculated using Eq. (43) ... 

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