Larger Aromatic Complexes of the Group 3 Metals and Lanthanides

Back to the future of organolanthanide chemistry

“…These requirements are reminiscent of the lanthanide multiple-decker chemistry developed with large aromatic ligands such as Cot and its substituted analogs. 25,222 Monometallic sandwich compounds have already shown promising results, as in the case of titanium for example, which also demonstrated that the presence of protons could not be as critical as anticipated with such ligands (Fig. 10).…”

“…4). 36,77,[116][117][118][119][120][121][122] With the recent introduction of novel organometallic architectures as supporting ligands, such as large ring ligands, 25,36,37 further development in this field is likely to be expected. The development of ligand structures inducing long luminescence lifetimes is highly desirable for lightpromoted photoredox reactions to maximize the probability of an electron transfer from the organolanthanide complex to the substrate.…”

“…As such, derivatives of the versatile Cp and Cot ligands were used and constitute most of the sandwich complexes made in this area. 23,25 Once the novelty of those arrangements wore off, the structural properties were primarily designed for the reactivity of the complexes. One key example is the development of the pentamethylcyclopentadienyl ligand (Cp*) and the corresponding Sm II and Yb II complexes as base-free or solvate adduct versions.…”

“…The size mismatch between the small cyclopentadienyl ligand and the large metallic f-elements has been easily corrected by increasing the size of the aromatic ligand used, either by substituting the hydrogens with bulkier groups 23,24 or using larger aromatic rings. 25,26 Both methods proved very efficient in accessing sandwich compounds of various charges and oxidation states with f-elements.…”

“…As such, derivatives of the versatile Cp and Cot ligands were used and constitute most of the sandwich complexes made in this area. 23,25…”