Transition metal complexes are able to bind readily the dioxygen in the
reversible or irreversible manner. It is supposed that coordinated O2 is found
in activated state and, therefore, this allows the use of these compounds as
catalysts in the organic compounds.
In this work the activation of O2 are studied at its coordination to Mn (II) – bipy
compound. The calculations of the [Mn(bipy)2(H2O)2]2+ and [Mn(bipy)2(H2O)O2]2+
(in the Pauling ”end-on” and Griffith ”side-on” modes of oxygen molecule
coordination) systems were performed by the ab initio MO LCAO method in
the restricted open Hartree-Fock-Roothaan approximation at the STO-6G level.
The states with the value of the total spin S=1/2, 3/2 and 5/2 were determined
taking into consideration of the configuration interaction. The geometry
optimization and calculations of the electronic structure were carried out for the
[Mn(phen)2(H2O)2]2+ and [Mn(phen)2O2]2+ compounds in the C2 symmetry, and
for [Mn(phen)2(H2O)O2]2+ in the C1 symmetry.
The results of the total energy calculations (in atomic units of energy (a.u.e.))
in the optimized geometrical configurations are presented in the Table 1.
From the data of this table it is seen that the Pauling’s type of oxygen
coordination is energetically more convenient than the Griffith’s one. The activation
parameters of the oxygen molecule in the coordinated state (the”oxygen-oxygen”
bond lengthening, the decreasing of the dioxygen dissociation energy and the
value of the”oxygen-oxygen” stretching force) are estimated also.
This work was supported by the grant CRDF MC2- 3009.