Spectroscopic investigations of iron(II) and iron(III) oxalates

Abstract

Na tentativa de contribuir para uma melhor caracterização dos complexos de Fe II e Fe III com o ânion oxalato, uma investigação dos seus espectros vibracionais (infravermelho e Raman) e espectros Mössbauer de 57 Fe foi realizada. Foi observado que os dois polimorfos de FeC 2 O 4 . 2H 2 O, α and β, não podem ser diferenciados com exatidão por nenhum destes métodos espectroscópicos, demonstrando uma alta similaridade estrutural das duas formas cristalinas. Amostras parcialmente deuteradas de β-FeC 2 O 4 . 2H 2 O também foram investigadas para aprimorar a análise espectroscópica vibracional. No caso do Fe 2 (C 2 O 4 ) 3. 4H 2 O, um modelo estrutural pôde ser proposto a partir dos resultados dos dados vibracionais e de Mössbauer combinados. O espectro de Mössbauer registrado a 298 K para este complexo é discutido em detalhes pela primeira vez.In an attempt to contribute to a better characterization of Fe II and Fe III oxalate complexes, an investigation of their vibrational (infrared and Raman) and 57 Fe-Mössbauer spectra was performed. It is shown that the two polymorphs, α and β, of FeC 2 O 4 . 2H 2 O cannot be accurately differentiated with any of these spectroscopic methods, demonstrating the high structural similarity of these two crystalline forms. Partially deuterated samples of β-FeC 2 O 4 . 2H 2 O were also investigated to improve the vibrational-spectroscopic analysis. In the case of Fe 2 (C 2 O 4 ) 3. 4H 2 O, a structural model, derived from results of combined vibrational and Mössbauer data, could be proposed. The 298 K Mössbauer spectrum for this complex is discussed in detail for the first time.

Vibrational spectroscopic investigation of the hydrates of manganese(II) oxalate

“…2 shows those corresponding to α-Mn(C 2 O 4 ) · 2H 2 O. These spectra are practically identical to those recently reported for α-Fe(C 2 O 4 ) · 2H 2 O, [13] a fact which is not unexpected taking into account the commented structural analogy between both complexes. In the case of the trihydrate the very strong IR band at about 1600 cm −1 is most clearly splitted, as in the other two hydrates.…”

“…These assignments are based on the spectral behavior of 'free' oxalate [21] and in comparisons with well-known data derived from the studies of a great number of oxalate complexes [22] as well as on the result of our recent investigations of the dihydrates of Fe(II) oxalate [13] and of synthetic moolooite, Cu(C 2 O 4 ) · 0 · 2H 2 O [12] in which the Cu(II) cation presents in the plane an identical infinite-chain structural arrangement as that shown in Fig. 1.…”

“…[7 -9] As part of our studies of oxalate biominerals [2,4] and biomineralization processes in plants, [10,11] we have initiated different studies to attain a wider insight into the general physicochemical properties of metallic oxalates. [12,13] In this paper, we report the results of an investigation of the vibrational spectroscopic behavior of the three known hydrates of manganese(II) oxalate.…”

Characterization and Digital Restauration of XIV-XV Centuries Written Parchments by Means of Nondestructive Techniques: Three Case Studies

“…, and 780 cm −1 ) [33] and gypsum, as shown in Figure 4. e presence of oxalates can suggest a biological attack due to fungal species that can reprecipitate secondary carbonates Wavenumber ( Journal of Spectroscopyand biomineralize hyphae with both calcite and whewellite [29].…”

Synthesis of Nano Iron Oxalate – Structures and Optical Transitions

“…Mg, Mn, Fe, Co, Ni and Zn oxalates had been studied by XRD [4]. Fe(III) oxalate is rarely formed and was studied using Mossbauer, Raman and IR spectroscopy [5]. In the present work, the preparation and the spectral properties of nano oxalate of Fe(II) are studied using TEM, XRD and optical absorption spectroscopy.…”