Deuteron Magnetic Resonance Study in Co(ND3)6Cl3

Deuteron quadrupole coupling tensors in Co(ND3)6Cl3 were determined at various temperatures. The observed quadrupole coupling shows that Co(ND3)63+ ions execute a rapid isotropic reorientation at high temperatures (above 320°K for one of the sites (the 4f sites) and above 190°K for another (the 2e sites), while at low temperatures (below 190°K for the 4f sites, and 170°K for the 2e sites), only a C3 axis reorientation of the ligand ND3 groups is present. The deuteron resonance spectra clearly show that Co(ND3)63+ ions in the 4f sites begin to reorient about one of the three C4 axes at intermediate temperatures (about 240°K). On the basis of the orientation of quadrupole tensors, probable orientations of Co(ND3)63+ ions in the 4f sites in the crystal are proposed. Additional measurements of the proton resonance on a single crystal of Co(NH3)6Cl3support the results obtained from the deuteron resonance. To obtain the reorientation rates and the activation energies of these reorientational motions, the deuter...