AdNDP method

In Table 29.1, we summarized our results of electronic structure calculations for Bf -Bjj. We reported symmetry, spectroscopic state, valence electronic configuration, number of 2c-2e peripheral B-B a-bonds, number of delocalized o- and TT-bonds, and assignment of global aromaticity/antiaromaticity. The description of chemical bonding in terms of 2c-2e peripheral B-B a-bonds and nc-2e delocalized a- and tt-bonds was obtained via AdNDP method at... 

The detailed description of the AdNDP method and its application to boron clusters, prototypical aromatic hydrocarbons, gold clusters, metalloorganic complexes, and inorganic complexes containing metal clusters as the building blocks can be found elsewhere [58-64]. The AdNDP analysis allows us to introduce a new aromaticity criterion. A chemical species should be considered aromatic if there is a... 

Figure 14.9 Experimental structure of the [Pd4(P4-CgHg)(p4-CgHg)]+ sandwich complex. (a) The chemical bonding picture of the complex obtained via the AdNDP method ...

Therefore the X3 (X = Sc, Y, La) clusters satisfy the 4n -f 2 counting rule for a-aromaticity and the 4n - - 2 Huckel rule for Tt-aromaticity in cyclic systems with odd numbers of atoms (see Table 1). Thus, all three anions are d-orbital based doubly (a- and rr-) aromatic systems. The obtained via the AdNDP method 3c-2e d-AO based Or-bond and 3c-2e d-AO based rtf-bond are similar to the 3c-2e la i and la model molecular orbitals presented in Figs. 5 and 11, respectively. 

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