Lead optical electronegativities

Although we can conclude from the optical electronegativities that LMCT transitions play a role in the absorption spectra of lead thiolates, it is not currently known to what extent intraatomic transitions may also contribute to these bands, or what orbitals are involved in the transitions. There have been no detailed theoretical studies of lead-thiolate CT bands, and very little work in general has been reported on the absorption spectroscopy of Pb(II) coordination complexes. Although the absorption spectra have been reported for solid-state Pb(ll) alkaline earth sulfides (69-71), these data have not been analyzed extensively. In addition, much of the data that have been reported (69-71) are ambiguous due to insufficient information on sample preparation and composition (95). 

By contrast, if the opposite assumption is made—that the absorption bands are MLCT rather than LMCT—then the value calculated for Xopt(M) = 3.9, which is the optical electronegativity of fluoride on Jprgensen s scale (101). This result is completely untenable, lending further credence to the assertion that the lead-thiolate charge-transfer bands are LMCT in origin. 

Parameters of the three-dimensional structures function as operators between the properties of elements on the one hand, e.g., electronic structure, electronegativity, atomic radii, and properties of the compounds on the other hand, e.g., chemical reactivity, hardness, elasticity, ferroelectricity, electrical conductivity, optical rotatory power, refraction. Mathematical procedures lead from the elements to the structures and from the structures to the properties. If these are formulated as computer programs, they need data given in databases. If databases are used in this way, existing theories cannot only be demonstrated for individual examples but also verified as generally true. 

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