Typical values of g2S(S+1)τe (on which the paramagnetic relaxation and line broadening—in the absence of Curie-spin relaxation—depend) and of the axial paramagnetic susceptibility anisotropy (on which PCSs and pRDCs depend) for paramagnetic transition metal ions (a). In lanthanoid(iii) ions except gadolinium (b), relaxation is dominated by the Curie spin relaxation, which depends on gJ4J2(J+1)2τr (τr=10 ns, HS=high spin, LS=low spin, Oh=octahedral geometry, Td=tetrahedral geometry).