Bond-valence parameters of lanthanides

Ln—O and Ln—N bond-valence parameters have been computed in coordination complexes for lanthanides (Ln) at oxidation states other than +3 (Ce^IV, Sm^II, Eu^II and Yb^II). Moreover, Ln—Cl, Ln—S and Ln—C(π-bonded) bond-valence parameters are presented, as calculated for coordination compounds. In general, the bond-valence parameters decrease in the order Ln—O > Ln—C > Ln—N > Ln—Cl > Ln—S. It has been found that the values of bond-valence parameters decrease with increasing lanthanide atomic number for coordination compounds. As expected, the values of lanthanide–oxygen and lanthanide–nitrogen bond-valence parameters diminish with increasing lanthanide oxidation state. Several examples are given where the total valence of the lanthanide ion is apparently incorrectly assigned, as well as cases where bond-valence method calculations confirm the doubtful oxidation state assignment.