On the Proton Resonance of Several Hexammine Complex Salts

Abstract

Below liq. H₂ temperature down to liq. He temperature, it seems that the protons of NH₃ ligand are rotating or tunneling about three-fold axis in the complex ions of M(NH₃)₆ type. Above liq. H₂ temperature, there occurs the molecular reorientation in addition to the rotation or the tunneling of the protons of NH₃ about three-fold axis.
The difference of the line width between the diamagnetic and the paramagnetic salts at room temperature is explained by taking account of the short T₁ in the paramagnetic salts.
The magnitude of the observed shift at low temperature is proportional to the susceptibility and such a relation is derived theoretically by evaluating for three spin system. Comparing each line width and the shift of Co and Mn salts with those of Ni salt, it is suggested that the distance between hydrogen atom and the metal ion in Co and Mn salts is much larger than that in Ni salt. In the measurements on the salts of Ni(NH₃)₆Cl₂ and Ni(NH₃)₆(ClO₄)₂ at low temperature, there happened an unexpected phenomenon that the proton line disappears suddenly, though the reason of which is not yet certain.