Effect of a metal ion on intramolecular spin exchange in spin-labeled complexes

Article abstract of DOI:10.1007/BF02494758

The characteristic features of intramolecular spin exchange in 14 complexes of Ag^I, Hg^II, Ni^II, Pd^II, Pt^II, Au^III, and Pt^IV with spin-labeled ligands were studied by ESR spectroscopy. The measured values of the exchange integral |J and the differences between the enthalpies of the efficient conformations (ΔH) were compared with the electronic polarization (refraction) R_f of the Ni^II, Pd^II, and Pt^II ions and Klopman's rigidity parameters σ_K, which characterize the total polarazibility of the ions and the degree of covalence of the bond between the metal atom and the donor atom of the ligand, respectively. Delocalization of the electron spin density and the efficiency of spin exchange are determined by the relative contributions of the s, p, and d orbitals, which produce the overlap integral of wave functions, |J|, and by the geometric features of the coordination polyhedron, which affect the mutual orientation of the N-O fragments.