Crystal structure and absorption spectroscopy of a dimeric neodymium(III) complex with triethylenetetraaminehexaacetic acid (H6ttha), Na0.5H5.5[Nd2(ttha)2]·7.5NaClO4·16.83H2O
The crystal structure and absorption spectra (IR, UV/VIS) have been determined for Na0.5H5.5[Nd2(ttha)2]· 7.5NaClO4·16.83H2O (H6ttha = triethylenetetraaminehexaacetic acid). The structure consists of the complex dimer, perchlorate anions, sodium cations and water of hydration. Both neodymium(III) ions are nine-co-ordinate. Each ttha ligand is bonded to one NdIII through four of its carboxyl oxygen atoms and three of its nitrogen atoms. Two carboxyl oxygen atoms are bonded to the other NdIII, and the fourth nitrogen atom remains unco-ordinated. The co-ordination spheres of both NdIII are essentially the same and may be defined as distorted tricapped trigonal prisms. Absorption spectra of a single crystal were measured at room and liquid-helium temperatures. The intensities of the f–f transitions were analysed on the basis of Judd–Ofelt theory. Comparison of the absorption spectra of [Nd(ttha)]3– in solution to those of single crystals of Na3[Nd(ttha)]· 2.5NaClO4·7.617H2O and Na0.5H5.5[Nd2(ttha)2]·7.5NaClO4·16.83H2O compounds allowed us to estimate the ratio of mono- to di-meric species in solution.