Phosphoramides bearing isoxazole derivative: spectroscopic and structural characterization, study of hydrogen-bonding interactions and two lanthanide complexes (LnIII = Ce and Eu)

In this study, the synthesis and spectroscopic characterization of new phosphoramides based on 3-amino-5-methylisoxazole with the formula R2P(O)[NH-C4H4NO], R = C6H5O (1), C6H5 (2), RP(O)[NH-C4H4NO]2, R = C6H5O (3), CH3-C6H4O (4), C6H5NH (5), (C6H5)ClP(O)[NH-C4H4NO] (6) and two lanthanide complexes [Ln(2)2(NO3)3(EtOH)]·EtOH, Ln(III) = Ce (7) and Eu (8), have been reported. The structural study of (3) shows the presence of two conformers (crystallographically independent molecules) in the crystalline lattice, caused by different orientations of the phenyl and isoxazole rings. For (3), the intermolecular interactions have been studied by Hirshfeld surface analysis and fingerprint plots. Furthermore, the electronic and energy aspects of hydrogen bonds between molecules of (3) have been explored by density functional theory (DFT) calculations. X-ray crystallography of complexes (7) and (8) reveals that two phosphoramide ligands take part in coordination to the metal, one as monodentate from O(phosphoryl), and the other one as chelate through O(phosphoryl) and N(ring). The complexes are also composed of two conformers in the solid-state structure. Quantum theory of atoms in molecules (QTAIM) analysis discloses the electrostatic nature of the Ln-ligand interaction.

A click chemistry approach to 5,5'-disubstituted-3,3'-bisisoxazoles from dichloroglyoxime and alkynes: luminescent organometallic iridium and rhenium bisisoxazole complexes

5,5'-Disubstituted-3,3'-bisisoxazoles are prepared in one step by the dropwise addition of aqueous potassium hydrogen carbonate to a mixture of dichloroglyoxime and terminal alkynes. The reaction exhibits a striking preference for the 5,5'-disubstituted 3,3'-bisisoxazole over the 4,5'-regioisomer. Organometallic iridium and rhenium bisisoxazole complexes are luminescent with emission wavelengths varying depending upon the identity of the 5,5'-substituent (phenyl, butyl).