MOSSBAUER-SPECTROSCOPY AND ELECTRONIC-STRUCTURE CALCULATIONS OF THE NITRIDOFERRATES(III) - LI3[FEN2] AND BA3[FEN3]

An unusually negative isomer shift delta is found in the Mossbauer spectrum of the nitridoferrate(III), Ba3[FeN3]. A quantitative analysis of the delta values and the quadrupole splittings for Ba3[FeN3], Li3[FeN2], and a number of other iron compounds by band structure calculations gave a remarkably good linear correlation between delta and the calculated valence electron density. The weakest nuclear shielding by the valence electrons was found for the 3s electrons in Ba3[FeN3], which explains the delta value of -0.55(2) mms-1 relative to alpha-Fe.