Spectra of V(II), V(III), V(IV) and V(V) in 5.6 molar phosphoric acid

Abstract

The spectra of di, tri, tetra and pentavalent vanadium were measured in 5.6 molar H 3PO 4 media for the range of 10,000–53,000 cm −1. V(II) spectra were resolved into bands at 11,400,17,100 and 25,600 cm −1 with residues at 14,300 and 21,900 cm −1. The bands are probably due to 4 A 2 g → 4 T 2 g , 4 T 1 g ( F) and 4 T 1 g ( P) in an octahedral configuration. Residues are probably due to spin forbidden 4 A 2 g → 2 T 1 g , 2 E g transitions. For V(III), strong bonds were found at 15,150 and 23,250 cm −1 that can be attributed to 3 T 1 g → 3 T 2 g , 3 T 1 g in an approximately octahedral configuration. Weaker bands were found at 11,300 and 17,850 cm −1 that can be assigned to spin forbidden 3T 1 g → 1 E 1, 1 T 2 g and 1 A 1 g . In tetravalent vanadium, d-d transitions were found at 12,000, 13,400 and 14,800 cm −1 that can be assigned to 2 B 2 → 2 E( I), 2 B 1 and 2 A 1. The charge transfer spectra of V(V) showed transitions at 27,500, 34,750 and 51,000 cm −1. The V(V) charge transfer spectra may be used as evidence that the 41,00 cm −1 transition for V(IV) is probably a charge transfer rather than a d-d transition.