Sparkle/PM3 parameters for praseodymium(III) and ytterbium(III)

The Sparkle model, recently defined for Pr(III) and Yb(III) ions within AM1, is now extended to PM3. The Sparkle/PM3 unsigned mean error, for all interatomic distances between the trivalent lanthanide ion and the ligand atoms of the first sphere of coordination, is 0.09 Å for Pr(III); and 0.08 Å for Yb(III) a level of accuracy equivalent to the Sparkle/AM1 ones of 0.08 Å, and 0.08 Å respectively, as well as to results from present day ab initio effective core potential calculations.