Clusters elemental organic fragments

For the purpose of classification, the clusters reported so far, which combine transition metal atoms and either main group elements or elemental organic fragments in their frames, can be divided into the following categories on the basis of their structural features ... 

The synthetic approaches taken for the preparation of interstitial clusters are based on the activation of E-E, E-H, E-C, E-Si, E-O, E-S and E-Q bonds of suitable molecules. The methods to obtain clusters having exposed maingroup elements or elemental organic fragments are either exactly the same or differ only in their use of a source molecule which contains two kinds of E-X bonds... 

Ikble 3-9. Selected metal clusters containing exposed main group elements or elemental organic fragments (Category B). 

A direct derivation of the above approach made the synthesis of most of the clusters containing B, In, Si, Ge, Sn, P, As, Sb, S, Se, and lb interstitial heteroatoms or elemental organic fragments possible by the cleavage of E-H, E-G and E-C bonds under suitable experimental conditions. 

A few of the synthetic methods adopted so far are closely related to the previously examined methods used for the synthesis of clusters containing interstitial or exposed main group elements or elemental organic fragments. For example, as shown in Scheme 3-11, the very peculiar [Bi4Fe4(CO),3] cluster (see Section 3.2.6) has been obtained in two steps through classical redox condensation reactions or by the clockwise condensation induced by fragment elimination. [312] Related syntheses have also been used for the E-Co (E = Sb,Bi) [314, 315] and n-Fe [309] mixed clusters listed in Ihble 3-11. 

S.3 Structural characteristics of TVansition Metal Clusters Containii Interstitial or Exposed Main Group Elements or Elemental Organic Fragments... 

This function provides a normalized (i.e., between 0 and 1) representation of the extent to which two spectra are similar. Using this metric, a coincidence (or similarity) matrix, C, with elements Cy can be generated to tabulate the degree of similarity between the fragment catalogs of every pair of organisms. Likewise, a matrix of distances, D, with elements dy = (1 - Cy) can be created, and used as input to conventional cluster analysis algorithms. 

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