Nuclear-magnetic-resonance study of spin transfer to H in Rb2CuCl4∙2H2O and Rb2CuBr4∙2H2O

The nuclear magnetic resonance of 1H in Rb2CuCl4∙2H2O and isomorphic Rb2CuBr4∙2H2O has been measured at room temperature, near 165, and 77 K. The fractional spin transfer from the copper ion to hydrogen due to the transferred hyperfine interaction is analyzed: 0.22 ± 0.03% at 300 K, 0.25 ± 0.02% at 168 K, and 0.29 ± 0.02% at 77 K in Rb2CuCl4∙2H2O; and 0.22 ± 0.03% at 300 K, 0.28 ± 0.02% at 163 K, and 0.32 ± 0.02% at 77 K in Rb2CuBr4∙2H2O. The temperature-dependent spin transfers are discussed in terms of the molecular mass and the bond strength of the two compounds.