Modeling Lanthanide Coordination Complexes. Comparison of Semiempirical and Classical Methods

Abstract

A variety of approximate methods for efficient modeling of large lanthanide (Ln) complexes were studied. Attention was paid to ligand motifs prevalent in Ln coordination chemistry. Gadolinium was chosen given its central location in the Ln series and its importance in areas such as magnetic resonance imaging. A semiempirical approach based on a technique first described for europium was extended to gadolinium. Comparison with ab initio, molecular mechanics, and PM3 methods was performed for experimental and model complexes. Electrostatic models were found to be most reliable for cationic, large coordination number complexes with hard nitrogen and oxygen donorsan important subset of lanthanide complexes. When used for appropriate target complexes electrostatic models, particularly when used in conjunction with molecular mechanics, can be an effective and efficient technique for the study of large, experimentally relevant lanthanide coordination complexes.

Sparkle Model for AM1 Calculation of Lanthanide Complexes: Improved Parameters for Europium

“…T. R. Cundari et al have used the SMLC model for Gd(III) for the calculation of many Gd(III) coordination complexes and Gd(III) trihalides. For the last ones, they observed that the SMLC model predicts a wrong D 3 h geometry instead of the correct C 3 v due to its intrinsic electrostatic character . This behavior was reported by us 1 and by ab initio studies using various effective core potentials, ECPs .…”

Neodymium (III) and Samarium (III) Complexes of 2, 2′- ((1E, 1′E) - (1, 2- Phenylenebis(Azanlylidene) bis(Methanylylidene)) DiphenolLigand: Synthesis, Characterization and Biological Activity

“…Lanthanide complexes have been successfully applied as diagnostic tools in biomedical examination such as magneticr imaging. Compounds of gadolinium, for example, are widely used as contrast agents in magnetic resonance imaging(MRI) 6 . The lanthanides also, exhibit noticeable biological activity as some are capable of replacing Ca 2+ ion in organised molecules [7][8][9] .…”