Shuji Emori

Magnetic interaction between binuclear clusters in potassium trihalocuprates(II) and dimethylammonium trihalocuprates(II)

Abstract The magnetic susceptibilities of potassium trichlorocuprate(II), potassium tribromocuprate(II), dimethylammonium trichlorocuprate(II), and dimethylammonium tribromocuprate(II) were determined in a temperature range of 4.2–300°K and analyzed with the molecular field model, the Ising model, and the Heisenberg model. Spin interaction operators between copper atoms belonging to different dimer ions, [Cu 2 X 6 ] 2− , as well as between copper atoms within a dimer ion, the energy of interaction between the dimers amounting to 5–20% of the interaction energy within the dimer for potassium trihalocuprates(II) and to about 50% for dimethylammonium tribromocuprate(II).

Broad-line PMR spectra and magnetic susceptibilities of copper(II) complexes of pyrazine

Abstract The broad-line PMR spectra of dinitrato(pyrazine)copper(II), dichloro(pyrazine)copper(II), and dibromo(pyrazine)copper(II) were recorded at temperatures between 160 and 300 K. The powder crystals of the complexes show composite absorption curves having a low field shift. The composite shape of the observed curves is attributable to dipole-dipole interaction between neighboring protons in pyrazine. From the shift, the spin densities on carbon atoms of pyrazine were evaluated. The observed magnetic susceptibilities of the complexes conform to the linear Heisenberg model. The exchange integral for a pathway through pyrazine is very small compared with that for a pyridazine pathway in the corresponding copper(II) complexes of pyridazine. This can be explained qualitatively by a spin polarization mechanism.