Raman spectra of the lanthanide oxalates

Abstract

Raman and infrared spectral data are presented for the trivalent lanthanide sesquioxalates, M,(C,O,), * nH,O, except the promethium complex, in the region from 100 to 4000 cm-'. These complexes were isolated by precipitation from aqueous solution using Na,C,O, . In addition, several commercially available oxalate complexes were examined. On the basis of nearly identical Raman spectral patterns, two distinct structural groups have been identified. The first group consists of the isostructural (monoclinic) decahydrates of La3+ through Er". For this group, a linear correlation is found for the frequencies of several skeletal stretching modes versus the lanthanide ionic radius. The second group consists of the isostructural (triclinic) hexahydrates of Er3+ through Lu3+. In agreement with existing x-ray diffraction data, these vibrational data indicate structural differences between the hexa-and deca-hydrates. In addition, unique vibrational spectral patterns have been obtained for what appear to be other hydrated forms of the oxalates of Ho3+, Er3+ and Lu", possessing structures different from those of the above hexa-and deca-hydrates. For all of these complexes, the Raman data suggest that the oxalate ligand is tetradentate coordinated to two lanthanide ions. Thus, the structural differences undoubtedly result from the lanthanide contraction and changes in the disposition of coordinated and interstitial water molecules.

Spectroscopic Studies and Crystal Structures of Double Thorium(IV) Oxalates with Sodium Ions

“…Furthermore, the Raman spectrum of complex 2 appears to have two additional unique lines, a moderately strong band at 1068 cm –1 and a weak band at 725 cm –1 . The band near 1051 cm –1 was previously observed for the lanthanum oxalate complexes 34. However, the origin of these two extra bands is still under investigation.…”

Synthesis and characterization of Th1−xLnxO2−x/2 mixed-oxides

“…For 0.21 x Nd 0.84, the prepared oxalates were always polyphased. XRD revealed the presence of two to three crystalline structures in this range [43] and monoclinic P2 1 /c, which corresponds to the most common structure of Nd(C 2 O 4 ) 1.5 Á5H 2 O [60][61][62]. Finally, for x Nd = 0.97 and x Nd = 1, the monoclinic P2 1 /c structure was the only one stabilized.…”

“…From this data, one can find all the C-C and C-O related vibration bands of oxalate-based metal organic frameworks. The positions and assignment of all the observed bands are also given in supplementary data according to that proposed by Clavier et al [42] and Morris and Hobart [60]. From IR and m-Raman, the progressive splitting of some bands was noted when increasing the lanthanide content which suggests structural modifications with x.…”

Effect of neodymium doping on structural, microscopic and electrical properties of barium phosphate system

“…Fujitha et al 10 have suggested that the metal oxygen bands will appear around 800 cm À1 . Morris, 11 Gibson and Stump 12 have proposed the presence of another metal oxygen bands at 500 cm À1 . Comparison of the FTIR spectrum of NdBP with that of pure BP reveals a slight shift in some of the characteristically vibrational frequency because of Nd doping.…”