Phosphorus interatomic distance

Table 17 Actinide/Lanthanide-Phosphorus Interatomic Distances in their...

White phosphorus is a white, soft, wax-like transparent mass which often acquires a yellow appearance due to impurities, especially traces of red phosphorus. It has a garlic-like odor. It is made up of cubic crystals, has a density 1.82 g/cm3, and melts at 44.1°C to a colorless or yellowish liquid. X-ray diffraction studies and 3iP-NMR analysis indicate tetrahedral P4 molecules with an interatomic distance of 2.2 lA, and the molecules are able to rotate freely... 

EXAFS studies of A. vinelandii bacterioferritin have shown that there are fewer Fe-Fe contacts in the mineral core than occur with native horse ferritin, and those that do occur are at a greater interatomic distance. Moreover, the EXAFS data showed that the core iron of bacterioferritin had 5 to 6 phosphorus atoms no more than 3.17 A distant, thus supporting a model for the core of an amorphous Fe(III)-phosphate complex in which some of the phosphate bridges Fe(III) ions and some of it is nonbridging. 

GaCls. The presence of the triple bond is supported by the very short phosphorusnitrogen interatomic distance of 1.475(8) A measured by x-ray diffraction in the solid. A trifloromethanesulfonate salt [P=N Mes ]+ [OSO2CF3] (1) is also known and can be stabihzed by further coordination with 2,2 -bipyridyl and other donors, which make the phosphorus atom three-coordinate. ... 

The element phosphorus when condensed from the vapor forms waxy, colorless crystals, called white phosphorus. These crystals and the vapor contain P4 molecules, with the tetrahedral structure shown in the drawing. Each of the six interatomic distances in the molecule has the value 2.20 A. 

SAXS data showed that the molecules of the palladium complex [Pd2(PPh2)H c]n are nearly spherical in shape with a diameter of 15.6 A. EXAFS data showed that both the platinum, [(PPh2)Pt]8 -io, and palladium, [Pd2(PPh2)Hx] , complexes contained only phosphorus and metal atoms in the first coordination sphere. The interatomic distance between Pt(Pd) and the phosphorus atoms is 2.26 A, which is typical of the Pt(Pd)-P distances in platinum and palladium complexes. Comparison with the spectral data of the reference compound, Pd(PPh3)4, showed that each platinum atom is surrounded by four phosphorus atoms (the coordination number, u(P/Pt), is four). The corresponding value for palladium atoms, (P/Pd), is three. 

Also determined by this method are some interatomic distances (see Table 3). Metal-halide and metal-phosphorus distances found by EXAFS for (Ph3P)3RhCl are in reasonable agreement with those determined crystal-lographically. 

Table 3,6. Interatomic distances in some gallium-phosphorus dimeric and trimeric supermolecules.

Table 3.10. Interatomic distances in indium-phosphorus supermolecules.

Possible symmetrical arrangements of up to nine neighbours around a central P atom are depicted in Figure 3.4. Most of these have been found in phosphorus compounds and in nearly all cases the experimental interatomic distances indicate chemical bonding of some kind. The majority of these configurations can be rationalised in terms of traditional single , double or triple bond concepts (see below). 

The range of experimental interatomic distances found between a phosphorus atom P and another (non-metallic) atom X, can be depicted by the scheme in Figure 3.13. 

Solid state studies by x-ray diffraction have shown that interatomic distances are sometimes greater than expected for a single covalent bond (primary bond), but less than the Van der Waal radius sum of the two atoms concerned. The concepts of secondary bonding and dative bonding are sometimes invoked to explain these unusual distances which have been observed in widely differing phosphorus (and other) compounds. 

If radicals are formed in solution, what happens upon vaporization Around this time, studies of the gas-phase structures of the phosphorus and arsenic compounds were initiated in two separate gas electron diffraction (GED) laboratories. It was soon clear that in both cases the compounds were effectively 100% dissociated in the gas phase. However, determination of the molecular structures of the P[CH(SiMe3)2]2 and As[CH(SiMe3)2]2 radicals was a very difficult undertaking as in GED studies resolution of similar interatomic distances is difficult if not impossible. In P[CH(SiMe3)2]2 there are P—C distances and inner and outer Si—C distances, which are aU nearly the same, and there are similar problems with non-bonded distances, P Si, Si Si and C C. In As[CH(SiMe3)2]2 the problems are essentially the same. There are also distortions due to steric crowding, and the molecules have little symmetry (C2 in the gas phase). 

All rare-earth monophosphides have the NaCl-type structure (Bragg 1914). It is characterized by octahedral coordination of phosphorus atoms (fig. 8). The interatomic distances (6r p = l/2a) are close to the sum of atomic radii of the components. 

The crystal structure of CeP2 belongs to NdAs2-type (fig. 10). The phosphorus atoms have CPs in the form of tetragonal pyramids (PI) and distorted tetrahedra (P2) with one or two additional phosphorus atoms, respectively (fig. 10). The phosphorus atoms form fragments of zigzag-like chains (fig. 10). The interatomic distances vary between 0.4064 and 0.3932 (Ce-Ce) 0.3127 and 0.2919 (Ce-P) 5p, P2 = 0.2404 5p2-p2 =0.2453. 

A projection of the crystal structure of NdPs (Wichelhaus and von Schnering 1976) is shown in fig. 14. The CPs of all phosphorus atoms are distorted tetrahedra formed by neodymium and phosphorus atoms (fig. 14). Zigzag-Uke chains of phosphorus atoms are joined with one another by P3 atoms and form a fimnework. No Nd-Nd contacts occur in NdPs structure. Interatomic distances are riNd-p=0.3046-0.2991 5p p = 0.2211-0.2162. 

The structure type LaPs (Wichelhaus and von Schnering 1976) is closely related to the NdPi-type and differs from it by a double lattice parameter a (fig. 15). In both structures the CPs of the phosphorus atoms and their bond types are identical. Interatomic distances are Sta-p=0.3121-0.3035 6p p=0.2216-0.2167. 

The coordination of phosphorus atoms in the EuPy-type structure (von Schnering and Wittmann 1980) is the same as in the LaPy-structure (fig. 17). The phosphorus atoms are linked in ribbons of complicated configuration (fig. 17). The distances between the phosphorus atoms in the ribbons vary between 0.2235 and 0.2180, while those between phosphorus atoms from different ribbons are about 0.350. The interatomic distances Eu-P are 0.3262-0.3062. 

Analysis of the minimum interatomic distances in structures of binary phosphides (table 18) does not show any clear tendencies. The 5r p largely depends on the atomic radius of R and to a smaller degree on the phosphide composition. Hovewer, some increase of the minimum interatomic distances 5r p is observed in phosphides with higher phosphorus contents. The minimum value of the (5p p for most phosphides corresponds to the P-P distances in the phosphorus modifications, 0.221 (white phosphorus) and 0.224 (red phosphorus) with an average value of 0.2219 (Hittorf phosphorus)... 

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