High-pressure MnP₄, a polyphosphide with Mn–Mn pairs

Abstract

The new compound MnP4 was prepared by reaction of the elemental components at pressures of 30-55 kbar in a tetrahedral anvil high-pressure device. It is a diamagnetic semiconductor with an activation energy of 0-14 eV and crystallizes with space group C2/c, a= 10.513 (1), b= 5.0944 (4), c= 21-804 (2) A, fl=94-71 (1) °, and Z= 16. The structure was determined from single-crystal counter data by Patterson and Fourier methods and refined to a conventional R of 0.051 for 1765 reflections. The Mn atoms are in octahedral P coordination, and the P atoms are tetrahedrally coordinated by Mn and P atoms. The Mn atoms have formal oxidation number 2 + (d 5 configuration). Four MnP6 octahedra share edges to form a linear array of four Mn atoms. The Mn atoms are displaced from the centers of the octahedra toward one another to form pairs with a resulting Mn-Mn bonding distance of 2.941 A, thus accounting for the diamagnetism. Average Mn-P and P-P distances are 2.282 and 2-225 ,£,, respectively. MnP4 can be described as an eight-layer stacking variant of the two-layer CrP4 structure, although bonding within and between the layers is of equal strength. Qualitative MO bonding models for the MnP4 and CrP4 structures are presented that allow rationalization of magnetic and conductive properties. A similar bonding proposal is made for the marcasite and arsenopyrite structures which, as is the case for CrP4 and MnP4, have TPo octahedra linked via edges, with transition metal atoms forming infinite strings and pairs, respectively.

High-pressure phases with ordered defect PbFCl-type structures in the systems V–P and Nb–P

“…3. ) Ideal single-bond P-P distances in elemental P modifications and polyphosphides are close to 2.21 + 0.02A (Dahl, 1969;Jeitschko & Donohue, 1975).…”

“…Because of temperature gradients in the cylindrical samples, the reaction products generally consisted of several phases of which the low-pressure compounds VP2 (Hulliger, 1964), NbP (Boller& Parth6, 1963, and NbP2 (Rundqvist, 1966a) were identified through their powder patterns. In samples with a V:P ratio of 1:2-5 excess black P was observed, indicating the absence of high-pressure compounds with compositions similar to CrP4 (Jeitschko & Donohue, 1972) and MnP4 (Jeitschko & Donohue, 1975).…”

Preparation and structure of technetium triphosphide and rhenium triphosphide, isotypic polyphosphides with metal chains

“…The other two 4d electrons use the two remaining orbitals to form one half-a and one half-7~ bond to each of the two neighboring Tc atoms. The metal-metal bonding in TcP a (and ReP3) corresponds to the bonding in the d 4 marcasites where it has been discussed in more detail before (Jeitschko & Donohue, 1975). The Tc-Tc bond length of 3.092 (1)/k and the Re-Re bond length of 3.122 (2)A (this distance is equivalent to the b axis) seem rather long at first sight, but one has to keep in mind that it is the result of a compromise involving considerable deviations from ideal octahedral and tetrahedral bond angles as has been discussed above.…”

“…A similar net, consisting only of puckered pentagons, was recognized (Jeitschko, 1974) to be the basic building element of many TX 2 (X = pnicogen or chalcogen) compounds including the structures of pyrite, marcasite, arsenopyrite, PdP 2, PdS2, and PdPS. Similarly, many polyphosphides of composition TP 4 can be visualized as stacking variants of a related puckered net consisting of pentagons and hexagons (Jeitschko & Donohue, 1975;Rfihl & Jeitschko, 1981). The ratios of pentagons to hexagons in the nets of the structures with the general compositions TX2, TX 3, and TX 4 are 4:0, 3: 1, and 2:2.…”

Stacking variants of MnP4: preparation and structure of 6-MnP4

“…The first of these compounds, CrP4, was prepared in a well crystallized form at high pressure (15-65 × 10 2 MPa) but could also be obtained at 3 x 10 2 MPa (Jeitschko & Donohue, 1972) and, more recently, by the tin-flux technique (Braun, 1976;Braun & Jeitschko, 1978). A compound with the composition MnP 4 was also first prepared at high pressure (Jeitschko & Donohue, 1975) but was synthesized later at lower pressure (Braun, 1976;Braun & Jeitschko, 1978;von Schnering, 1976). More recently, the preparations, crystal structures and properties of a-FeP 4 (Jeitschko & Braun, 1978;Grandjean, G6rard, Krieger, Heiden, Braun & Jeitschko, 1980), fl-FeP 4 (Sugitani, Kinomura, Koizumi & Kume, 1978), RuP 4 and OsP 4 (Braun & Jeitschko, 1978), and ReP 4 (Jeitschko & Riihl, 1979) have been described.…”