Configuration and State Correlation

The state symmetries of heteronuclear diatomic molecules are simpler than those of homonuclear diatomics the g and u states of Doo/i simply coalesce in Coot . Table 3.2 summarizes the correlations of the irreps of Doo/i with those of its subgroup Coov and between the latter and those of C2v  

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Figure 6.18. Excited-state barriers a) orbital correlation diagram for a thermally forbidden conversion of an alternant hydrocarbon b) the corresponding configuration and state correlation diagram for the case that Ihe HOMO— LUMO excitation does not represent the longesl-wavelength absorption.

Fig. 5a and b. Correlation diagram for electron configurations and states in the cyclobutene-butadiene interconversion a) conrotatory motion, b) disrotatory motion... 

Lowdin, P.-O., and Redei, L., Combined use of the methods of superposition of configurations and correlation factor on the ground states of He-like ions."... 

In contrast to chloride compounds, niobium oxides have a VEC of 14 electrons, due to an overall anti-bonding character of the a2u state, caused by a stronger Nb-O anti-bonding contribution. In some cases, the VEC cannot be determined unambiguously due to the uncertainty in the electron distribution between the clusters and additional niobium atoms present in the majority of the structures. The 14-electron compounds exhibit semiconducting properties and weak temperature-independent paramagnetism. Unlike niobium chlorides, the oxides do not exhibit a correlation between the electronic configuration and intra-cluster bond distances. 

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