Di- and Triphenylacetates of Lanthanum and Neodymium. Synthesis, Structural Diversity, and Application in Diene Polymerization

A new family of lanthanide complexes with di- and triphenylacetate ligands was prepared from LnCl₃. Dimeric diphenylacetates were the only isolated products of the reaction between LnCl₃ (Ln = La, Nd) and Ph₂CHCOONa. The exchange reaction between LnCl₃ and Ph₃CCOONa led to the formation of three structurally different types of neodymium and lanthanum complexes under different reaction conditions. Various coordination modes of the carboxylate ligands were revealed, including κ²- and κ¹-terminal coordination, μ₂-κ¹:κ¹-bridging, and μ₂-κ¹:κ²-semibridging. The treatment of La and Nd tris-triphenylacetates with excess AlEt₃ produces the dimeric tetraethylaluminates [Ln₂((μ₂-κ¹:κ¹-Ph₃CCOO)₄(AlEt₄)₂]. The structures of the key La and Nd triphenylacetates that were obtained from these reactions were verified by X-ray diffraction, and the complex [(THF)₄Nd₂(Ph₂CHCOO)₂(μ₂-κ¹:κ²-Ph₂CHCOO)₂(μ₂- κ¹:κ¹-Ph₂CHCOO)₂] was studied by high-resolution X-ray diffraction. Neodymium di- and triphenylacetate complexes can serve as precursors of catalysts for butadiene and isoprene stereospecific 1,4-cis polymerization

Polyphenylcyclopentadienyl Ligands as an Effective Light-Harvesting π‑Bonded Antenna for Lanthanide +3 Ions

A new approach to design “antenna-ligands” to enhance the photoluminescence of lanthanide coordination compounds has been developed based on a π-type ligandthe polyphenyl-substituted cyclopentadienyl. The complexes of di-, tri-, and tetraphenyl cyclopentadienyl ligands with Tb and Gd have been synthesized and all the possible structural types from mononuclear to di- and tetranuclear complexes, as well as a coordination polymer were obtained. All types of the complexes have been studied by single-crystal X-ray diffraction and optical spectroscopy. All terbium complexes are luminescent at ambient temperature and two of them have relatively high quantum yields (50 and 60%). Analysis of energy transfer process has been performed and supported by quantum chemical calculations. The role of a low-lying intraligand charge transfer state formed by extra coordination with K⁺ in the Tb³⁺ ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes containing π-type ligands with desired luminescence properties have been proposed