Atanasov, Mihail Comba, Peter Daul, Claude 2006-11-14 Exchange coupling across the cyanide bridge in a series of novel cyanometalate complexes with Cu^II-NC-M^III (M = Cr and low-spin Mn,Fe) fragments has been studied using the broken-symmetry DFT approach and an empirical model, which allows us to relate the exchange coupling constant with σ-, π-, and π*-type spin densities of the CN⁻ bridging ligand. Ferromagnetic exchange is found to be dominated by π-delocalization via the CN⁻π pathway, whereas spin polarization with participation of σ orbitals (in examples, where the d<i>_z </i>² orbital of M^III is empty) and π* orbitals of CN⁻ yields negative spin occupations in these orbitals, and reduces the Cu^II- M^III exchange coupling constant. When the d<i>_z</i>² orbital of M^III is singly occupied, an additional positive spin density appears in the σ(CN) orbital and leads to an increase of the ferromagnetic Cu- NC-M exchange constant. For low-spin [M^III(CN)₆]³⁻ complexes, the d<i>_z</i>² orbital occupancy results in high-spin metastable excited states, and this offers interesting aspects for applications in the area of molecular photomagnetism. The DFT values of the exchange coupling parameters resulting from different occupations of the t_2g orbitals of low-spin (t_2g⁵) Fe^III are used to discuss the effect of spin-orbit coupling on the isotropic and anisotropic exchange coupling in linear Cu-NC-Fe pairs. application/pdf https://folia.unifr.ch/global/documents/300595 https://folia.unifr.ch/documents/300595/files/daul_dsm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1021/jp066020q info:eu-repo/semantics/openAccess License undefined The Journal of Physical Chemistry A. - 2006, vol. 110, no. 49, p. 13332 -13340 info:eu-repo/classification/udc/54 DFT studies on the magnetic exchange across the cyanide bridge http://purl.org/coar/resource_type/c_6501