New bond-valence parameters for lanthanides.

The bond-valence method, especially the valence-sum rule, is very useful for checking if the structures formed by trivalent lanthanides are correct. In this work bond-valence parameters (Rij), which connect bond valences and bond lengths, have been computed for a large number of bonds taken from the Cambridge Structural Database, Version 5.24 (2002) [Allen (2002). Acta Cryst. B58, 380-388]. The calculated values of bond-valence parameters for metal-organic compounds decrease with an increase in lanthanide atomic number; the Rij values are also smaller than bond-valence parameters calculated for inorganic compounds. A summary of bond-valence sums calculated for Rij given in this work and reported in the literature, and a functional correlation between lanthanide-oxygen distances and coordination number are presented.