Sparkle model for AM1 calculation of neodymium(III) coordination compounds

The Sparkle/AM1 model, the only available semiempirical quantum chemical model for the calculation of complexes of lanthanide ions, recently defined for Eu(III), Gd(III) and Tb(III), is now extended to Nd(III). Accordingly, all 57 Nd(III) complexes of high crystallographic quality (R-factor < 0.05 Å), possessing oxygen or nitrogen as directly coordinating atoms, present in the Cambridge Structural Database 2003, were considered. A subset of 15 structures was chosen by cluster analysis to constitute the parameterization training set. All 57 complexes were considered back in the validation part, and the Sparkle/AM1 unsigned mean error, for all interatomic distances between the Nd(III) ion and the ligand atoms of the first sphere of coordination, was found to be 0.07 Å, a level of accuracy useful for luminescent complex design and comparable to present day rare earth complex ab initio/ECP calculations, while being hundreds of times faster.