Group 13 nitrides cluster

The IR spectra of endohedral Li3 xMxN C80, where 0 < x < 3, M = Sc, Y, Tb, Ho or Er, include vibrations of an encaged trimetal nitride cluster.2 The Raman spectra of the D2d symmetry species M2 C84, where M = Sc, Y or Dy, show three groups of metal-cage modes in the range 35-200 cm-1. Variable-temperature data for M = Y shows that there is an order/disorder transition near 150 K.3... 

This result emphasizes the role of interstitial atoms in determining the electronic structure and the properties of these materials. The NigCe core of the cluster can be regarded as a microscopic fragment of a nickel carbide. The interstitial main group atoms form strong bonds with the surroundings these bonds may be viewed as initial step in the formation of a different phase (carbides, nitrides, etc.) within the cluster complex. 

In both metal lattices and closo polyhedral metal clusters there are cavities present, whose dimensions are a function of the number of vertices, the shape of the polyhedral moiety, and the interatomic separation. Partial occupation of these sites within the metal lattice by main group elements results in the formation of interstitial alloys such as, for example, metal hydrides, carbides, and nitrides. Occupation of the cavity within a molecular metal cluster gives rise to interstitial clusters. Although close topological relationships are sometimes found between interstitial alloys and interstitial clusters, the greater degree of freedom of a molecular assembly of metals, in comparison to a three dimensional infinite array of metals, increases the possible number of interstitially lodged elements... 

The electrochemistry of mononuclear metal - sulphur complexes and metallo-sulphur clusters which interact with dinitrogen (or other substrates and inhibitors of the enzyme) or which bear groups such as hydrazide, nitride, or amide are consequently of some relevance to biological nitrogen fixation. 

Besides interstitial carbon atoms, nitride groups have also been used to stabilize the cluster structure of iron-rhodium and iron-iridium hydroformylation catalysts [18]. 

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