Europium complexes: choice of efficient synthetic routes from RM1 thermodynamic quantities as figures of merit

Abstract

We advance the novel general idea that thermodynamic quantities of chemical reactions from RM1 quantum chemical calculations, regarded as figures of merit, are useful to the chemist studying europium complexes. Faced with several different plausible synthetic pathways for the preparation of a given europium complex, the synthetic chemist can now easily compute the RM1 thermodynamic quantities for all of them. As we show, regarding the results as figures of merit, the chemist has a high likelihood of arriving, in an a priori manner, at the most effective synthetic strategy. We further introduce the concept of series of ligands, ordered in terms of their relative displacement abilities in ligand exchange reactions. First, we calculate this series for a few β-diketonate ionic ligands: DBM > BTFA ≈ TTA. Then, we show how this series can help the experimentalist decide, of all possibilities, which would be the most efficient sequence of addition of ionic ligands to obtain the best total reaction yield for the syntheses of mixed ionic ligand europium complexes; and exemplify with two alternate syntheses of [Eu(DBM)(BTFA)(TTA)(TPPO)₂]. The synthetic route that added the ionic ligands according to the calculated series exhibited a yield of 76%; whereas the one that inverted that series displayed less than half that yield: 37%. Then, we introduce the series of relative displacement abilities for the non-ionic ligands considered: both monodentates (both as single ligands and as pairs of ligands) and bidentates: (TPPO,TPPO) > BIPY > PHEN ≈ (PTSO,PTSO) > (DBSO,DBSO) > TPPO > PTSO > DBSO > H₂O. In conclusion, there is seemingly a wealth of useful information to the lanthanide chemistry experimentalist that can be obtained from RM1 quantum chemical calculations of thermodynamic quantities.