ChemInform Abstract: Discovery of γ‐MnP₄ and the Polymorphism of Manganese Tetraphosphide.

Abstract

Discovery of -MnP 4 and the Polymorphism of Manganese Tetraphosphide. -The new title polymorph of MnP 4 is synthesized by chemical vapor transport of a stoichiometric mixture of manganese and red phosphorus using iodine as transporting agent (evacuated silica tubes, temperature gradient 1073923 K, 14 d). -MnP 4 crystallizes in the monoclinic space group Cc with Z = 8 (single crystal XRD) and is isostructural with -FeP 4. All four binary polymorphs in the MnP4 system are stacking variants of nets built of Mn and P atoms. Mn 2 dumbbells exist in the structure of -MnP4. Magnetic and electrical conductivity measurements show diamagnetism and a small anisotropic band gap of 100-200 meV. DFT calculations show that all known stacking variants of MnP 4 exhibit similar bonding, energy, and thermodynamic properties. -(HENGE, D. B.; HERMUS, M.; LITTERSCHEID, C. F.; WAGNER, N.; BECK, J.; ALBERT*, B.; BRGOCH, J.; Inorg. Chem. 54 (2015) 17, 8761-8768, http://dx.doi.org/10.1021/acs.inorgchem.5b01372 ; Eduard-Zintl-Inst. Anorg. Phys. Chem., TH Darmstadt, D-64287 Darmstadt, Germany; Eng.) -W. Pewestorf 46-016

Structural Diversity and Electronic Properties of 3d Transition Metal Tetraphosphides, TMP4 (TM = V, Cr, Mn, and Fe)

“…11−13 For γ-MnP 4 , the metastable nature is revealed by its formation enthalpy, higher than that of 6-MnP 4 by 36 meV/fu; this agrees well with the high annealing temperature (923−1073 K) during synthesis, and it is difficult to separate from the mixture of manganese tetraphosphides. 14 For iron tetraphosphide (FeP 4 ), the formation enthalpy of α-FeP 4 is close to that of γ-FeP 4 (higher by about 11 meV/fu), whereas β-FeP 4 is higher than γ-FeP 4 by about 64 meV/fu, agreeing with the synthesis at high temperature and high pressure conditions (1373 K and 6 GPa) for β-FeP 4 . 16 Additionally, the calculated phase transition can be found for FeP 4 in Figure 1, γ-FeP 4 transforms into α-phase at 2.8 GPa then to β-phase at 4.9 GPa.…”