Control of Oxidation States of Transition Elements (Cr, Mn) in Nitridometalates and the Solid Solution Series Li₆(Ca_1‐xSrx)₂[Mn₂N₆]

Abstract

The formation of ternary nitridometalates from the elements in the case of the systems Li—Cr, V, Mn—N leads to compounds which contain the transition metals in the highest (VV, CrVI) or a comparably high (MnV) oxidation state. In the corresponding calcium and strontium systems, the transition metals show a lower oxidation state (VIII, CrIII, MnIII). Transition metals with intermediate oxidation states (CrV, MnIV) are present in the quaternary (mixed cation) compounds Li4Sr2[Cr 2VN6], Li6Ca2[Mn 2IVN6], and Li6Sr2[Mn 2IVN6] (R3¯(#148), a = 585.9(3) pm, c = 1908.6(4) pm, Z = 3), as well as in the solid solution series Li6(Ca1—xSrx)2[Mn 2IVN6].

Ce2[CrN3]: Single Phase Synthesis and Characterization of a Nitridochromate(I)

“…oxides and halides +7 is not observed so far, however, Li 7 [MnN 4 ] contains Mn V in tetrahedral coordination 11,12. For oxidation states of +4 Mn–Mn bonding together with threefold coordination of each manganese atom by nitrogen in Li 6 Ca 2 [Mn 2 N 6 ] and Li 6 Sr 2 [Mn 2 N 6 ] is observed 13,14. Further compounds with Mn in +4 and +3 exclusively contain manganese in threefold coordination by nitrogen (Sr 8 [MnN 3 ] 3 ,15 Li 24 [MnN 3 ] 3 N 2 ,12 (Ca 3 N) 2 [MnN 3 ],16 Ca 3 [MnN 3 ],17 Sr 3 [MnN 3 ], Ba 3 [MnN 3 ]18).…”

Case of a Strong Antiferromagnetic Exchange Coupling Induced by Spin Polarization of a Mn–Mn Partial Single Bond

“…In the case of the quaternary nitridomanganates(IV) Li 6 Ca 2 [Mn 2 N 6 ] and Li 6 Sr 2 [Mn 2 N 6 ] presented by Kniep et al , the Mn 2 units are located within octahedra of nitride anions N 3– , forming unsupported Mn IV –Mn IV contacts within ethane-like [Mn 2 N 6 ] 10– units with distances d (Mn–Mn) of 2.36 and 2.54 Å for the calcium and strontium compounds, respectively. The electronic structures of these crystalline compounds have been investigated by solid-state density functional theory (DFT) calculations and subsequent analysis of the evaluated electron localization function.…”

The Reduced Nitridogermanates(III) Ca6[Ge2N6] and Sr6[Ge2N6] with Ge−Ge Bonds

“…Each of those compounds features ethane‐analogue [ Tt 2 Ch 6 ] 6− ions. Related compounds in the nitridometalate chemistry of transition metals include the homeotypic hydride Ca 6 [Cr 2 N 6 ]H, [24] as well as Sr 2 Li 6 [Mn 2 N 6 ] and Ca 2 Li 6 [Mn 2 N 6 ], [25, 26] which contain [Mn IV 2 N 6 ] 10− anions in a similar rhombohedral packing motif.…”