Closed-shell complexes

The spectroscopic properties of these closed-shell complex anions are drastically changed if metal ions which are easily oxidized enter the second co-... 

In our opinion this shows that the thermal quenching temperature of the luminescence of the closed-shell complexes depends more strongly on the energy difference between the parabolae than on their offset ). In fact only the colourless complexes are able to show luminescence of any importance. 

Since no advanced calculations on the square-pyramidal closed-shell complexes are available, it is difficult to understand the low transition probability in the emission. As a matter of fact we have the spin selection rule prohibiting fast decay from the excited triplet level. A simple m.o. approachshows that it is hard to see where an orbital selection rule would originate from. The long decay time is then ascribed to orbital overlap restriction, but a more quantitative approach is necessary. 

In this section, however, we wish to discuss another phenomenon, viz. that the spectral properties of the closed-shell complex are changed drastically by the presence... 

Fig. 31a-d. Several possibilities for the splitting of the Tj level of a tetrahedral closed-shell complex, (a) cubic symmetry without spin-orbit coupling, (b) S4 symmetry without SO coupling, (c) cubic symmetry with SO coupling (level sequence as deduced from decay-time measurements on CaW04). (d) as (c) (level sequence as deduced from decay-time measurements on PbMoO4). After Ref. 74... 

Hence, for the Ft complex, the scalar-relativistic DKH Hamiltonian and the spin-orbit ZORA-Hamiltonian recover relativistic effects on the electron density of the valence region found in four-component calculations. This is particularly remarkable since the DKH density has not been corrected for the picture-change error in these calculations. The difference density maps for the Ft complex clearly show the importance of the scalar-relativistic contraction of the inner shells, while spin-orbit effects can be neglected for this closed-shell complex (otherwise, the DKH results would deviate much more from the fourspin-orbit-coupling-induced splitting of the d shell is small but noticeable. 

Stabilization of C28 by an endohedral species is a fascinating topic especially as the C28 cage provides itself 28 electrons, and has the ability to accept four electrons in the LUMO allowing a route to a 32 electrons closed-shell M C2s system. Because of the quasi monoreference (94.3%) nature of the ground state of C28 [38] one can expect that the DFT is an appropriate theoretical framework for the study of the An C2s closed-shell complexes. 

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