Introduction
The knowledge of the molecular nature of matter and of its changes constitutes at
the present the necessary pathway to understand the chemical properties and the
reactivity. The goal is, based on molecular properties, also inclusive of the electronic properties, to reach more valuable and extensive laws in chemistry. The
complexity of studying even a simple inorganic molecule suggests that approximate
methods have to be used in the quantum mechanical treatment, taking also into
account the macroscopic peculiarities of the chemicals, e.g., their molecular shape.
In the case of inorganic molecules, a convenient approximation source comes
from the symmetry, which constrains the electronic energies and the chemical
bonds to follow its rules. Thus, the first part of the present text will give special
emphasis to the symmetry properties in the frame of group theory and will compare
the use of symmetry operators with that of Hamiltonian operators. If possible, also
the reactivity of the molecules will be rationalized in terms of symmetry properties.
Electronic spectroscopy and magnetism will be used to provide the experimental
confirmation of the electronic energy levels.
The description starts with a short summary of the variation and the perturbation
methods together with a limited description of the group theory, in order to
demonstrate how the symmetry rules simplify the application of the methods.
The electronic structure of simple inorganic molecules is then described as an
example by symmetry-adapted linear combinations of atomic orbitals.
Well-studied coordination compounds with different symmetries, regular and
distorted, are described by using the crystal and ligand field approaches.
Their electronic structure is confirmed by electronic spectra and magnetic
measurements.
Finally, a large number of examples taken from the scientific literature, reported
the capability of the so determined electronic structure to explain the chemical
properties of the systems and in some case their functionality (both chemical and
physical).
An appendix of mathematics useful to understand the theoretical descriptions is
reported.
ix
The knowledge of the molecular nature of matter and of its changes constitutes at
the present the necessary pathway to understand the chemical properties and the
reactivity. The goal is, based on molecular properties, also inclusive of the electronic properties, to reach more valuable and extensive laws in chemistry. The
complexity of studying even a simple inorganic molecule suggests that approximate
methods have to be used in the quantum mechanical treatment, taking also into
account the macroscopic peculiarities of the chemicals, e.g., their molecular shape.
In the case of inorganic molecules, a convenient approximation source comes
from the symmetry, which constrains the electronic energies and the chemical
bonds to follow its rules. Thus, the first part of the present text will give special
emphasis to the symmetry properties in the frame of group theory and will compare
the use of symmetry operators with that of Hamiltonian operators. If possible, also
the reactivity of the molecules will be rationalized in terms of symmetry properties.
Electronic spectroscopy and magnetism will be used to provide the experimental
confirmation of the electronic energy levels.
The description starts with a short summary of the variation and the perturbation
methods together with a limited description of the group theory, in order to
demonstrate how the symmetry rules simplify the application of the methods.
The electronic structure of simple inorganic molecules is then described as an
example by symmetry-adapted linear combinations of atomic orbitals.
Well-studied coordination compounds with different symmetries, regular and
distorted, are described by using the crystal and ligand field approaches.
Their electronic structure is confirmed by electronic spectra and magnetic
measurements.
Finally, a large number of examples taken from the scientific literature, reported
the capability of the so determined electronic structure to explain the chemical
properties of the systems and in some case their functionality (both chemical and
physical).
An appendix of mathematics useful to understand the theoretical descriptions is
reported.
ix