D° configuration, special properties

We may expect that the future will see many additional uses of cationic zirconocenes in organic synthesis, in which their Lewis acidic character, coupled with the special properties of zirconium (oxophilic, fluorophilic) and its d°-electron configuration (leading, for example, to weak back-bonding) will come into play. 

Considering the special bioactive and biocatalytic functions of copper(II) carboxylate complexes,[9] along with the magnetic properties and various coordination fashions of Cu(II) ion,[10-12] we focused our work on the Cu(II) and H4btec system. Based on the layer structure of [Cu2(btec)(H20) -4H20] (1),[13] in which the Cu(ll) atom with bi-pyramidal configuration is coordinated by two monodentate carboxyl O atoms and three aqua molecules, part of the coordinated aqua molecules of Cu(II) is possible to be replaced by some bridging spacers, such as pyrazine, 4,4 -bipyridine (4,4 -bpy) and the related species, and to construct 2-D and 3-D open-frameworks with variable cavities and channels. 

Compared with the lanthanides or the transition metals, the actinide elements introduce a striking array of novel chemical features, displayed most clearly in the chemistry of uranium. There is the variety of oxidation state, and to some extent the chemical diversity, typical of transition metals in the same periodic group, but physical properties which show that the valence electrons occupy /-orbitals in the manner of the lanthanides. This raises the question of the nature of the chemical bond in the compounds of these elements. The configuration of the uranium atom in the gas phase is f3ds2, so it is natural to ask whether there are special characteristics of the bonding that reflect the presence of both/and d valence orbitals. 

It should be remembered, of course, that Lie groups have an independent existence apart from their role in the theory of f electrons in the lanthanides. Some of the bizarre properties that turn up in the f shell might well derive from isoscalar factors that receive a ready explanation in another context. An example of this is provided by the vanishing of the spin-orbit interaction when it is set between F and G states belonging to the irreducible representation (21) of G2. In the f shell, (21) is merely a 64-dimensional representation of no special interest. However, for mixed configurations of p and h electrons, it fits exactly into the spinor representations (iiiHi 2) of SO(14) with dimensions 2 (Judd 1970). These are the analogs of the spinor representations of eq. (130), and (21) describes the quasiparticle basis of the configurations (p-t-h)". The spinor representations of SO(3) and (Hiii) of SO(ll) provide the quasi-particle bases for the p and h shells respectively and their SO(3) structures, namely S 1,2 and 512+ 912+ is/2> when coupled, must yield the L structure of (21) of G2, namely D-l-F-l-G-l-H-t-K-t-L. In this context, the F and G terms of (21) are associated with the different irreducible representations Sj,2 and S9/2. It is this property,... 

Correlations between electronic configurations for the elements and the periodic table arrangement of elements make it possible to determine a number of details of electronic structure for an element simply on the basis of the location of the element in the periodic table. Special attention is paid to the last or distinguishing electron in an element. Elements are classified according to the type of subshell (s, p, d, f) occupied by this electron. The elements are also classified on the basis of other properties as metals, nonmetals, or metalloids. 

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