f‐Block Phospholyl and Arsolyl Chemistry

The f‐block chemistry of phospholyl and arsolyl ligands, heavier p‐block analogues of substituted cyclopentadienyls (CpR, C5R5) where one or more CR groups are replaced by P or As atoms, is less developed than for lighter isoelectronic C5R5 rings. Heterocyclopentadienyl complexes can exhibit properties that complement and contrast with CpR chemistry. Given that there has been renewed interest in phospholyl and arsolyl f‐block chemistry in the last two decades, coinciding with a renaissance in f‐block solution chemistry, a review of this field is timely. Here, the syntheses of all structurally characterised examples of lanthanide and actinide phospholyl and arsolyl complexes to date are covered, including benzannulated derivatives, and together with group 3 complexes for completeness. The physicochemical properties of these complexes are reviewed, with the intention of motivating further research in this field. Rare earth and actinide phospholyl and arsolyl chemistry is reviewed herein, focusing on structurally characterised complexes where the binding mode of the ligand is well‐defined. A range of binding modes is shown for unsubstituted phospholyl rings, where M=rare earth or actinide metal and E=P, As or Sb; arsolyl binding modes are analogous.