STRUCTURE AND SPECTRAL EVALUATION OF COVALENCY IN ND(III) TETRAKIS COMPLEXES WITH CARBACYLAMIDOPHOSPHATE LIGANDS

Two neodymium(III) tetrakis complexes with different carbacylamidophosphate ligands and a tetraethylammonium cation of the formulas NEt4[NdL14] (1Nd) and NEt4[NdL24]·iPrOH (2Nd) were synthesized, where [L1]⁻ is dimethyl-N-trichloroacetyl­ami­­dophosphate, Cl3CC(O)NP(O)(OCH3)2⁻, and [L2]⁻ is diphenyl-N-trichloroacetylami­do­phosphate, Cl3CC(O)NP(O)(OC6H5)2⁻. The compounds were characterized by elemental analysis, infrared spectroscopy, diffuse reflectance electronic spectroscopy, and single-crystal X-ray diffraction analysis. Structural analysis confirmed the formation of anionic complexes featuring a NdO8 coordination environment. Coordination polyhedra of central ions are best described as a triangular dodecahedron for 1Nd and a square antiprism for 2Nd. Diffuse reflectance spectra in the UV–vis–NIR region revealed characteristic f–f transitions of NdIII, with ligand-dependent modulation of band shape and intensity of the “hypersensitive” transitions. The bonding between the metal and the ligands was found to have weak covalent character. Luminescence studies of the 2Nd complex revealed weak emission sensitization by the ligands.