P₂²⁻and P³⁻Units in the [Rh₈P₉]^δ−Polyanion of La₄Rh₈P₉

Abstract

The phosphide La(4)Rh(8)P(9) was synthesized from the elements in a bismuth flux. The structure was refined from single crystal diffractometer data: space group Cmcm, a = 1303.1(2), b = 1893.2(2), c = 576.70(6) pm, wR2 = 0.0277, 1380 F(2) values, 65 variables. The rhodium and phosphorus atoms build up a three-dimensional [Rh(8)P(9)] polyanion which leaves larger cages for the three crystallographically independent lanthanum sites. The rhodium atoms have between four and six phosphorus neighbors at Rh-P distance ranging from 229 to 254 pm. Three of the four crystallographically independent phosphorus atoms are isolated (P(3-) units), while the P4 atoms form dimers with double bond character (208 pm P-P). The P(2)(2-) diphosphenide units bond side-on to a Rh3 and end-on to four Rh5 atoms. (31)P magic angle spinning (MAS) NMR spectroscopy is able to resolve three of the four crystallographically distinct phosphorus sites. The doubly bonded phosphorus site P4 is characterized by an axially symmetric shielding tensor of moderate anisotropy Δσ = σ(33) - σ(iso) = 257 ppm. Electronic band structure calculations prove the metallic character and reveal the significant difference between the isolated P(3-) and the phosphorus atoms of the P(2)(2-) units. Magnetic susceptibility measurement reveals Pauli paramagnetism.

Triclinic La7Zn2P11 with P3−, P24−, and P35− units: a combined study by 31P solid-state NMR spectroscopy and single crystal X-ray diffraction

“…They have to adjust to the three different phosphide species with different charges. This is comparable to the structures of La 4 Rh 8 P 9 (288.6-345.9 pm) 52 or La 3 Zn 2−x P 4 (294.0-306.2 pm). 9 The final crystal chemical question concerns the driving force for the triclinic structure.…”

PbP7– a polyphosphide with a three-dimensional [P7]2−network of condensed and P-bridged P6hexagons

“…a solution assisted metathesis reaction Na 3 P + BiCl 3 → BiP + 3NaCl. 13 During our systematic bismuth and lead-flux assisted synthesis of phosphides, [14][15][16] we also tried synthesis of lead phosphides through a low-temperature route with several annealing steps along with a lead flux. These studies led to the first lead polyphosphide PbP…”

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“…Initially, well‐shaped Ho 3 Rh 9 Si 2 Sn 3 single crystals were obtained during an attempt to grow “HoRh 6 Sn 4 ” single crystals from a bismuth flux. This technique has recently successfully been used for the growth of germanide9,12 and phosphide13,14 single crystals. Therefore the elements (500 mg in the ideal stoichiometric ratio 1:6:4) were melted in an arc‐furnace15 in an argon atmosphere of about 700 mbar.…”