ON THE INTERACTION BETWEEN AZIDE AND MANGANESE IONS AT SEVERAL OXIDATION STATES

Abstract

The interaction between azide and manganese ions, at several oxidation states (II, III, IV, V, VI and VII), has been investigated in aqueous medium at 25.0 ± 0.1°C and ionic strength 2.0 mol · L⁻¹(NaClO₄). Spectral data were obtained from absorbance measurements in order to calculate the molar absorptivity. The molar absorptivity values calculated, at 430 nm, for [Mn(N₃)₃],[Mn(N₃)₄]⁻ and [Mn(N₃)₅]⁻² were 230, 3,700 and 6,600 mol⁻¹ · L · cm⁻¹, respectively. Mn(IV) and Mn(V) are not stable in azide aqueous solution medium and spectral characteristics are similar to Mn(III)/N₃₋ complexes. Additions of permanganate or manganese(VI) solution, as K₂ MnO₄, to several azide buffers solutions, N₃₋/HN₃, have produced species which have shown similar spectral characteristics with at 438 nm.

Keywords:

• Azide
• Manganese
• Spectrophotometric studies

ACKNOWLEDGMENTS

The authors gratefully acknowledge financial support from the Brazilian Foundations (CNPq and FAPESP).