Antimony atom

Antimony Trioxide. Antimony(III) oxide (antimony sesquioxide) [1309-64-4] Sb203, is dimorphic, existing in an orthorhombic modification valentinite [1317-98-2] is colorless (sp gr 5.67) and exists in a cubic form and senarmontite [12412-52-17, Sb O, is also colorless (sp gr 5.2). The cubic modification is stable at temperatures below 570°C and consists of discrete Sb O molecules. The molecule is similar to that of P40 and As O and consists of a bowed tetrahedron having antimony atoms at each corner united by oxygen atoms lying in front of the edges. This solid crystallizes in a diamond lattice with an Sb O molecule at each carbon position. 

Cyclic and Polymeric Substances Containing Antimony-Antimony Bonds. A number of oiganoantimony compounds containing rings of four, five, or six antimony atoms have been prepared. The first such compound to be adequately characterized, tetrakis-l,2,3,4-/f i-butyltetrastibetane [47191 -73-5], Cj H Sb, was obtained by the interaction of a dialkylstibide and iodine (70) ... 

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).

In [Me3Sb-SbMeI2]47 the trimethylstibine ligand is coordinated to the antimony atom of a T-shaped SbMeI2 moiety. The structure is depicted in Fig. la. 

The length of the coordinative bond (2.86 A) corresponds to a normal Sb-Sb single bond. The coordination geometries of the donor or acceptor antimony atoms are distorted tetrahedral for the former and pseudo trigonal bipyramidal for the latter with the iodine atoms in axial (I-Sb-I 169.71°) and the lone pair, the Me3Sb and the methyl group in equatorial positions. 

Fig. 10b) are similar. In all these complexes the antimony ligand is coordinated to the transition metal center in the apical position. The angles around the four coordinated antimony atom (100.8-106.8° in [(CO)4Fe(ri1-Ph2Sb-CH2-SbPh2)], 99.4-104.9° in [(CO)5W(V-Ph2Sb-CH2-SbPh2)], and... 

The coordination of the iron atom is distorted octahedral, with the CO groups in cA-positions to the antimony atoms being inclined towards the center of the heterocycle. 

Discrete [F(SbF3)4]" units are present in the crystals of KSb4Fi3 (39) and these consist of fluoride ions tetracoordinated by antimony(III) fluoride molecules through the antimony atoms. The coordinate bond lengths are 2.87 A and hence longer than the antimony-fluorine distances in the antimony(III) fluoride molecules, while the Sb-F bonds in the complex anion under consideration are 2.01 A and thus slightly longer than in the uncoordinated SbFs molecules (Fig. 4). 

The SbF6 ion has a central antimony atom with a ground state of 5s25p2 which is trivalent. If the 5s electrons were to be unpaired and one promoted to a 5d orbital the antimony would then be five-valent. If it accepted an electron to make it Sb and the electron was accommodated in another 5d orbital the ion would be six-valent and could accept the six electrons from the six ligand fluorine atoms to give a valence shell of six a pairs. This would indicate that the ion should have a regular octahedral shape. 

Antimony(III) halides are Lewis adds and will form adducts with Lewis bases. An example is provided by Lipka and Mootz,149 who prepared an adduct of diphenyl with SbCl3, 2SbCl3-PhPh (51). A molecule of SbCl3 is bonded to each of the biphenyl rings, but there are two differently bonded antimony atoms. One which forms the chain is six-coordinate there are three chlorine atoms at a normal distance, 2.36 A (av), and two at the longer distances of 3.443... 

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