FT RAMAN AND FTIR SPECTRA OF FOUR DISELENITES PbSe₂O₅, CdSe₂O₅, MnSe₂O₅ and Cr₂(Se₂O₅)₃

Abstract

The vibrational spectra of Lead diselenite, Cadmium diselenite, Manganese diselenite and chromium diselenite have been recorded and analysed on the basis of vibrations due to [Formula: see text] ion. The observed spectra clearly indicate the presence of diselenite group in all these compounds. The spectral analysis confirms the orthorhombic nature of MnSe 2 O 5 as suggested by Koskenlinna et al. A large number of vibrational bands in the symmetric stretching region of PhSe 2 O 5 is due to the existence of different Se-O bond lengths. From the spectra it can be seen that the anion is highly distorted angularly in chromium compound. This high distortion in all modes confirms the presence of three crystallographically distinct diselenite groups in chromium compound.

Selenium Oxoanion Compounds of Palladium(II)

“…Several weak bands centered at 560 cm -1 in these three IR spectra can be assigned to the distortions of the [PdO 4 ] square plane. , In the IR spectrum of PdSeO 3 , five sharp bands at 807, 730, 672, 621, and 591 cm -1 are attributable to the vibrational modes of SeO 3 2- . Four sharp bands occur at 828, 786, 722, and 675 cm -1 in the IR spectrum of PdSe 2 O 5 are due to the stretching vibrations of Se−O bonds within the Se 2 O 5 2- anions. , The vibration bands of SeO 4 2- in Na 2 Pd(SeO 4 ) 2 are found at 882, 869, 861, 846, and 832 cm -1 , and match well with the previously reported vibrational data for selenate …”

“…Diselenite compounds containing the Se 2 O 5 2- anion are becoming increasingly common in Se(IV) oxoanion chemistry, and are known with f-block metals, e.g., in UO 2 Se 2 O 5 , with alkaline-earth metals in AESe 2 O 5 (AE = Mg, Ca, Sr, Ba), and with d-block metals, e.g., in MnSe 2 O 5 , and [H 2 pip][Cu 2 (Se 2 O 5 ) 3 ] . MSe 2 O 5 (M = Pb, Cd, Mn) and Cr 2 (Se 2 O 5 ) 3 are also known and have been characterized by vibrational spectroscopy . The ammonium salt of diselenite, (NH 4 ) 2 Se 2 O 5 , has been studied by neutron diffraction and shown to undergo a phase transition at 312 K. − Despite the presence of two lone-pairs of electrons on the diselenite anion, most compounds are centrosymmetric; notable exceptions include LiFe(Se 2 O 5 ) 2 , Nb 2 Se 4 O 13 , Nd 2 (Se 2 O 5 ) 3 ·H 2 SeO 3 ·2H 2 O, and In 2 (Se 2 O 5 ) 3 .…”