β-Diketonate Ln3+ Chelates, Stereoisomerism and X-Ray Diffraction Studies of Facial Complexes Under Photochemical Condition

Abstract

Conversion, separation and characterisation of meridional isomer of series of facial—lanthanide (Br–β–diketonato/β–ketoester)₃ under photochemical condition is reported. When irradiated at λ=254 nm, the facial stereoisomer—[Ln(Br–β–diketonato)₃·2H₂O] 2H₂O readily isomerises giving a product which has, on the basis of NMR and IR spectral details, been identified as the meridional isomer. The continuous photolysis on facial—[Ln(Br–β–ketoester)₃·2H₂O] 2H₂O readily hydrolyse which has, on the basis of X-ray diffraction data, been identified as Ln(CH₃COO)₃·4H₂O.Fac → Mer stereiosomerism under thermal condition while met with failure.