Hexanuclear clusters electronic structures

In compliance with the nuclearity principle, polynuclear clusters are subdivided into a number of other subgroups, e.g. hexanuclear, octanuclear, etc. The binuclear clusters of technetium may be classified according to the electronic structure of their Tc-Tc2 bonds. Then, the d4-d4 complexes with quadruple M-M bonds are the father of all binuclear complexes with Tc-Tc bonds. The addition or removal of electrons from Tc-Tc bonds [1,11] should result in a decrease in the formal multiplicity of M-M bonds. Thus, for instance, the formal multiplicity of Tc-Tc bonds of d3-d3 and d5-d5 binuclear complexes equals3 3, that of d4 d5 and d4-d3 complexes equals 3.5, etc. 

The electronic structures for many hexanuclear clusters adopting the basic geometries displayed in Figs. 1 and 2 have been investigated using a variety of computational methods (30, 35-47). We will therefore only briefly summarize the results obtained from DFT calculations performed—by methods described in detail elsewhere (30, 44, 45)—on a few representative examples. 

The effect of long-range electron transfer on chemiluminescence of the hexanuclear cluster ion Mo6Cl f in the presence of three series of structurally and electronically related organic compounds (aromatic amine radical cations A+, nitroaromatic... 

Returning to [Co6N(CO)i5] and [Rh6N(CO)i5] , both of these are 90-electron hexanuclear clusters. As such they adopt a more open structure than octahedral clusters containing 86 electrons, i.e., [Ru6N(CO)i6] . 

The hexanuclear cluster [Os6(CO)ig] (69) and the corresponding dianion [69] are notable since the structural change from the bicapped tetrahedron of 69 (170) to the octahedron of osmium atoms in [69f (171) is exactly that predicted by polyhedral skeletal electron-pair theory (172). 

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