Spin Density Distribution in Transition Metal Complexes: Some Thoughts and Hints
Abstract The spin density distribution in transition metal complexes is discussed in qualitative terms, taking into account the coexistence of spin delocalization and spin polarization mechanisms, with the help of numerical results for several complexes obtained from density functional calculations. The covalent character of the metal-ligand bonds as well as the σ- or π-characteristics of the partially filled d orbitals must be taken into account to qualitatively predict the sign of the spin density at a particular atom within a ligand. The same patterns can be applied to binuclear complexes and can be helpful in determining the ferro- or antiferromagnetic character of the exchange coupling…
Exchange Coupling in Cyano-Bridged Homodinuclear Cu(II) and Ni(II) Complexes: Synthesis, Structure, Magnetism, and Density Functional Theoretical Study
The synthesis and structural characterization of several new cyano-bridged copper(II) and nickel(II) homodinuclear complexes is presented. The measure of magnetic properties for these complexes is complemented with a computational study of the exchange coupling for several model structures representing this family of compounds. The influence of several factors on the coupling constant has been examined, coordination position occupied by the bridging ligand, distortions of the coordination environment, and relative disposition of the cyanide ion with respect to the M-M vector. Comparison of experimental and calculated coupling constants allows for the rationalization of the most relevant fea…
X-X through-cage bonding in Cu, Ni, and Cr complexes with M3X2 cores (X=S, As).
Density functional calculations on trinuclear complexes bridged by two sulfur atoms, [(tmeda)(3)Cu(3)(mu-S)(2)](3+), [(tmeda)(3)Ni(3)(mu-S)(2)](2+), and [(tmeda)(3)Ni(3)(mu-S(2))](4+), as well as on the formation of [(tmeda)(3)Cu(3)(mu-S)(2)](3+) from a dinuclear [(tmeda)(2)Cu(2)(mu-S(2))](2+) complex and a mononuclear [(tmeda)Cu(eta(2)-S(2))](+) fragment, are reported. A qualitative orbital analysis of the M(3)X(2) framework bonding is presented for the case in which each metal atom M has a square planar coordination sphere completed by one bidentate or two monodentate ligands (that is, [(L(2)M)(3)X(2)] compounds). It is concluded that a framework electron count (FEC) of 12 corresponds to …
ChemInform Abstract: Spin Density Distribution in Transition Metal Complexes: Some Thoughts and Hints
Abstract The spin density distribution in transition metal complexes is discussed in qualitative terms, taking into account the coexistence of spin delocalization and spin polarization mechanisms, with the help of numerical results for several complexes obtained from density functional calculations. The covalent character of the metal-ligand bonds as well as the σ- or π-characteristics of the partially filled d orbitals must be taken into account to qualitatively predict the sign of the spin density at a particular atom within a ligand. The same patterns can be applied to binuclear complexes and can be helpful in determining the ferro- or antiferromagnetic character of the exchange coupling…