Insight into the Electronic Structure, Optical Properties, And Redox Behavior of the Hybrid Phthalocyaninoclathrochelates from Experimental and Density Functional Theory Approaches

An insight into the electronic structure of several hafnium­(IV),
zirconium­(IV), and lutetium­(III) phthalocyaninoclathrochelates has
been discussed on the basis of experimental UV–vis, MCD, electro-
and spectroelectrochemical data as well as density functional theory
(DFT) and time-dependent DFT (TDDFT) calculations. On the basis of
UV–vis and MCD spectroscopy as well as theoretical predictions,
it was concluded that the electronic structure of the phthalocyninoclathrochelates
can be described in the first approximation as a superposition of
the weakly interacting phthalocyanine and clathrochelate substituents.
Spectroelectrochemical data and DFT calculations clearly confirm that
the highest occupied molecular orbital (HOMO) in all tested complexes
is localized on the phthalocyanine ligand. X-ray crystallography on
zirconium­(IV) and earlier reported hafnium­(IV) phthalocyaninoclathrochelate
complexes revealed a slightly distorted phthalocyanine conformation
with seven-coordinated metal center positioned ∼1 Å above
macrocyclic cavity. The geometry of the encapsulated iron­(II) ion
in the clathrochelate fragment was found to be between trigonal-prismatic
and trigonal-antiprismatic.