Synthesis, structure, and some properties of 1-phenyl-3-methyl-4-(2,3,4,5,6-pentafluorobenzoyl)pyrazol-5-one and its lanthanide complexes

A new 4-acylpyrazolone-1-phenyl-3-methyl-4-(2,3,4,5,6-pentafluorobenzoyl)-1H-pyrazole-5(4H)-one (Pfb-PMPH)-was prepared in a high yield by the reaction of 1-phenyl-3-methylpyrazol-5-one with pentafluorobenzoyl chloride in the presence of calcium and barium hydroxides. On heating this compound in vacuum up to 170A degrees C, elimination of HF takes place to give the intramolecular cyclization product, 1-phenyl-3-methyl-5,6,7,8-tetrafluorochromeno[2,3-c]pyrazol-4(1H)-one. The structures of Pfb-PMPH (HL1) and the cyclization product (L-2) were determined by X-ray diffraction (CIF files CCDC nos. 1010331 (HL1), 1010332 (L-2), 1010333 (VI), 1010334 (VII), 1010335 (VIII), 1010336 (IX), and 1010337 (X)). The reactions of Pfb-PMPH with lanthanide silylamides [(Me3Si)(2)N](3)Ln in a THF solution give pyrazolonate complexes (Pfb-PMP)(3)Ln(THF) (Ln = Sm, Eu, Gd, Tb, Lu). The compounds react with Ph3PO to give the derivatives (Pfb-PMP)(3)Ln(OPPh3)(2) center dot xEtOH, which were studied by X-ray diffraction. The synthesized lanthanide complexes are luminescent at room temperature and exhibit ligand- and metal-centered emission.