Recent advances in the syntheses and structures of some lanthanoid group 15 heterocyclic complexes

Full text: Novel rare earth pyrazolate complexes of the general formula [Ln(η2 -RR'pz)3 (solvent)n] may be prepared by the redox transmetallation/ligand exchange reaction. Representative X-ray structures for R = R' = But or Ph, or R = Me, R'= Ph have shown monomeric structures with three η2-pyrazolate ligands, which have the centres of the N-N bonds and the metal near coplanar. Thallium(I) pyrazolate complexes have been synthesised by treating appropriate pyrazoles with thallium(I) ethoxide in a variety of solvents. These thallium(I) pyrazolates were then treated with lanthanoid metal to afford the first lanthanoid(II) pyrazolate complexes. A crystal structures of a lanthanoid(II) pyrazolate complexes of the type Ln(Phpz)2 (dme)2 have been determined which also exhibit a monomeric structures with h2-pyrazolate ligands despite low steric constraints. Other lanthanoid(II) pyrazolates have also been prepared and their structures determined. Treatment of a related thallium(I)diphosphastibolyl complex with ytterbium metal afforded the first tris(diphosphastibolyl)-lanthanoid complex. Two diphosphastibolyl rings were bound in an η5 fashion and the third was bound η2