Antimony , crystal structure

Figure 7.6. A filled. skutterudite antimonide crystal structure. A transition niclal atom (Fc or Co) at the centre of each octahedron is bonded to antimony atoms at each corner. The rare earth atoms (small spheres) are located in cages made by eight octahedra. The large thermal motion of rattling of the rare earth atoms in their cages is believed be responsible for the strikingly low thermal conductivity of these materials (Sales 1997).

This bismuth-III structure is also observed for antimony from 10 to 28 GPa and for bismuth from 2.8 to 8 GPa. At even higher pressures antimony and bismuth adopt the body-centered cubic packing of spheres which is typical for metals. Bi-III has a peculiar incommensurate composite crystal structure. It can be described by two intergrown partial structures that are not compatible metrically with one another (Fig. 11.11). The partial structure 1 consists of square antiprisms which share faces along c and which are connected by tetrahedral building blocks. The partial structure 2 forms linear chains of atoms that run along c in the midst of the square antiprisms. In addition, to compensate for the... 

The reaction of the hexakis(cyclohexylamino)cyclotriphosphazene 136 with 3 equiv of antimony trichloride, in THF and in the presence of triethylamine, resulted in the formation of compound 137 (Equation 13). This compound was recrystallized from a mixture of THF and hexane and the crystal structure unambiguously assigned the structure <2005IC275>. The dimer, compound 138, was formed at room temperature from compound 139 and R3P (R = 7-Pr, Ph). Upon dissolution, compound 140 was formed <2002ZFA1903>. 

Monomeric carbene complexes with 1 1 stoichiometry have now been isolated from the reaction of 4 (R = Bu, adamantyl or 2,4,6-trimethylphenyl R = H) with lithium l,2,4-tris(trimethylsilyl)cyclo-pentadienide (72). The crystal structure of one such complex (R = Bu) revealed that there is a single cr-interaction between the lithium and the carbene center (Li-C(carbene) 1.90 A) with the cyclopentadienyl ring coordinated in an if-fashion to the lithium center. A novel hyper-valent antimonide complex has also been reported (73). Thus, the nucleophilic addition of 4 (R = Mes R = Cl) to Sb(CF3)3 resulted in the isolation of the 1 1 complex with a pseudo-trigonal bipyramidal geometry at the antimony center. 

The compound 4(Ph3SbI)2OI2 is obtained by the addition of I2 in acetonitrile/water to a solution of triphenyl-antimony. The crystal structure contains a one-dimensional chain 53 and (Ph3SbI)20 molecules which are not coordinated to I2. In the ID chain, the distance between the iodine of the (Ph3SbI)20 molecule and the diiodine... 

Physically, antimony s properties are related to sulfur and some of the nonmetals, but chemically, its properties are related to metals. It behaves like a metal and is often found in nature along with other metals. In its pure form it is rather hard and britde with a grayish crystal structure... 

In the latter, the valency angles must be about 100°, so the layers cannot be flat. Their shape is obtained if, in Figure 38, the atoms shown with the clear circles are displaced somewhat below the plane of the paper and the shaded ones similarly, above it. If the layers formed in this way are then arranged on top of one another, the crystal structure of the elements arsenic, antimony and bismuth are obtained in their normal forms in which they have metallic properties. There also exists a modification of phosphorus with a similar structure. In addition, there are other forms of arsenic and antimony, the properties of which correspond to those of yellow phosphorus these forms contain molecules p As4 and Sb4. 

Antimony(III) halides are powerful halide acceptors and form complexes with, for example, monovalent halides to give a variety of interesting structures, e.g. (54)-(56). The tetramethyl-ammonium nonabromodiantimonate(III) dibromine is of interest since the crystal structure contains bromine molecules which bridge the [Sb2Br9]3 anions (56).158... 

One of the more notable features of antimony(V) halide chemistry is the tendency to achieve a CN of six, thus resulting in the facile formation of complex anions, particularly with halide donors (Table 21) the d(Sb—F) depends on the nature of the cation. Their structures are related to the F—Sb- -F interactions between crystal structure units, which is dependent upon the potential field of the cation. 

Antimony pentachloride reacts with alkali pseudohalides (equation 50). Addition of further KX results in dimer formation, [SbCl4X]2. The crystal structure of [SbCLN3]2 shows a distorted... 

The X-ray crystal structure of [Pv TPP(OH)2 ]OH 2H2 O has been determined.32 The porphyrin skeleton is distorted S4 symmetrically to attain short P—distance ( 1.90 A). The hydroxy groups are strongly intermolecularly hydrogen bonded, and the phosphorus atom is displaced from the N4 plane by 0.096 A. The antimony(V) ion is centred in the porphyrin plane in [Sb(OEP)(OH)2]+ with a somewhat large Sb—distance of 2.065(6) A.31 The structure of [Bi(OEP)]NO, is of interest, since the four-coordinate BiUI ion protrudes from the porphyrin N4 plane by 1.09 A with a very long Bi—Npor distance of 2.32 A.31... 

The product shall have the characteristic shining, needlelike structure, steel-grey color, and hardness of the naturally occurring crystalline mineral. The lump form of the antimony sulfide shall be clean and free from adherent gangue material or scale. Pulverized antimony sulfide shall be free from extraneous material as indicated by visual examination under a magnification that clearly shows the crystal structure. The manufacturer shall certify that the product has these physical characteristics... 

The crystal structure of antimony pentachloride, SbCls, is hexagonal (D (, P63 jmmc, a0 = 7.49, and c0 = 8.01 A) with two molecules in the cell. The molecules are hep giving the simple notation 2P(h). In Figure 4.26, we see that the trigonal bipyramidal molecules have their C3 axes parallel to c0, the packing direction. The axial Sb—Cl distance is 2.34 A and that in the equatorial plane is 2.29 A. The closest Cl—Cl distances (3.33 A) are between axial Cl atoms between adjacent molecules. 

A ternary compound of cerium with copper and antimony of the stoichiometric ratio 3 3 4 was identified and studied by means of X-ray analysis by Skolozdra et al. (1993). Ce3Cu3Sb4 compound was found to have the Y3Au3Sb4 type with the lattice parameters of a = 0.9721 (X-ray powder diffraction). For experimental details, see the Y-Cu-Sb system. At variance with this data, Patil et al. (1996) reported a tetragonal distortion of the cubic crystal structure Y3Cu3Sb4 for the Ce3Cu3Sb4 alloy which was prepared by arc melting the constituent ele-... 

---