Cluster compounds ligands

Johnson et al. (132) have also discussed the validity or otherwise of such analogies. Spectra from the same type of surface species that give similar vibrational spectroscopic patterns can show readily measurable frequency variations that may be much more significant in reactivity terms. However, it seems clear that in many cases the overall spectral patterns of cluster-compound ligands do provide useful and reliable fingerprints for identifying the structures of surface species. 

These carbene (or alkylidene) complexes are used for various transformations. Known reactions of these complexes are (a) alkene metathesis, (b) alkene cyclopropanation, (c) carbonyl alkenation, (d) insertion into C-H, N-H and O-H bonds, (e) ylide formation and (f) dimerization. The reactivity of these complexes can be tuned by varying the metal, oxidation state or ligands. Nowadays carbene complexes with cumulated double bonds have also been synthesized and investigated [45-49] as well as carbene cluster compounds, which will not be discussed here [50]. 

Table 6.3 Ligand arrangement and structural properties in reported niobium oxychloride cluster compounds.

In view of this, it is not surprising that dithiocarbamato compounds with copper in the oxidation state + 3 are stable instead it must be regarded as unexpected that Cu(I) dithiocarbamato complexes exist. The latter complexes are not simply monomeric, but they are tetrameric metal cluster compounds. Obviously, the stability must be attributed to the metal-metal bond rather than to the stabilising effect of the ligand. 

The Wade rules can be applied to ligand-free cluster compounds of main-group elements. If we postulate one lone electron pair pointing outwards on each of the n atoms, then g — 2n electrons remain for the polyhedron skeleton (g = total number of valence elec-... 

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