The calculations on magnetic exchange interaction of Cl3FeOFeCl3 2- and the related modeling compounds were performed by using the density functional theory coupling the broken symmetry approach. The calculated results show the absence of a direct Cl3Fe-FeCl3 magnetic coupling and the effect of the terminal Cl ligands on magnetic exchange interaction in [Fe-O-Fe]4+, while the protonation of

The geometry structure, dissociation energy, vibrational frequencies, and low-lying spin-state energy spectrum of Mn2+ are investigated by using ab initio CASSCF/ECP10MDF, complete active space self-consistent field/atomic natural orbital basis sets CASSCF/ANO-s, CASPT2/ECP10MDF, and second-order perturbation theory with CASSCF reference function/atomic natural orbital basis sets CASPT2/ANO-s levels of theory. For the ground state the dissociation energy of 1.397 eV calculated at the CASPT2/ANO-s level supports Jarrlod's experimental value of 1.39 eV. The equilibrium bond length and vibrational frequency are 2.940 Å calculated at the CASPT2/ANO-s level of theory and 214.4cm−1 calculated at the CASSCF/ANO-s level of theory, respectively. On the basis of the mixed-valence model, the Heisenberg exchange constant J−71.2cm−1 and the double-exchange constant B 647.7cm−1 are extracted explicitly from the low-lying energy spectrum calculated at the higher levels of theory. The magnetic competition between the weaker Heisenberg exchange interactions and the stronger double-exchange interactions makes the ground state a 12g+ state, consistent with electron paramagnetic resonance experimental observation, which explains unusual magnetic properties of Mn2+, quite different from the antiferromagnetic ground state of Mn2 and Cr2. On the other hand, the results calculated at the higher levels of theory show the consistent antiferromagnetic Heisenberg exchange interactions between 3d−3d for Cr2, Mn2+, and Mn2.

Magnetic exchange interaction for the μ-hydroxo bridged vanadium (IV) dimers is investigated based on calculations of density functional theory combined with the broken-symmetry approach. It is found that there is an exponential correlation between the V-O (hydroxo)-V angle, the V-O (hydroxo) distance and the exchange coupling constants J. Meanwhile, the calculated results reveal that the deprotonation of the bridging hydroxo ligand causes a sharp increase of the exchange coupling interaction, but the magnetic coupling constant J is insensitive to the deprotonation of the bridging aquo ligand. Moreover, simplifying each 1,2-bridging squarate ligand with two OCH2 groups almost does not influence magnetic exchange behavior between the two vanadium (IV) ions, and the principle of the shortest superex-change pathway is available for the multiplicity of the bridging ligand in the μ-hydroxo bridged vanadium (IV) di-mers.

The long disputed mechanism for the F2 addition to ethene is elucidated by density functional theory calculations. With hybrid functionals and a large basis set, DFT provides an excellent description for the dissociation of ground state F2, and a reasonable account for the F2

A useful parameter describing magnetic coupling interactions has been inspected in transition metal dimers, in which two transition metal ions are bridged by extended bis-bidentate ligands. This parameter is the square of overlap integral between the spatial parts of magnetic orbitals in the broken symmetry state. The oxalato-bridged Cu (II) dimers, in which the Cu (II) atom is either in tetrahedral or square pyramid coordination environment, have been calculated with the density functional theory coupling the broken symmetry approach.