Organoantimony halides

Diorganoantimony(V) trihalides seem to prefer six-coordinate, octahedral geometry, and as a consequence will associate into dimers. Thus, dimethylantimony(V) trichloride, Me2SbCl3, was found to be a dimer fMe2SbCl2(A/-Cl)]2, 154, with bridging chlorines, Sb-Cl 2.35 A and Sb- -Cl 2.80 A. A second isomeric form of this compound exists as an ion pair, [SbMe4]+[SbCl6] this illustrates the coordination preferences of antimony [391]. 

Diphenylantimony(V) trichloride is a chlorine-bridged dimeric supermolecule, [Ph2SbCl2( -Cl)]2 (terminal Sb-Cl 2.388 A, bridging Sb-Cl 2.620 A, Sb- -Cl 2.839 A) [392]. The adduct Ph3SbCl2-SbCl3 is a tetranuclear self-assembled supermolecule, 155, also formed via secondary Sb- - -Cl interactions (Sb-Cl 2.306-2.354 A, Sb- - -Cl 3.236 and 3.287 A) [393]. 

Methyldichlorostibacydopentane forms cyclic tetramers, 156, in the crystal [394], Another supermolecular structure is illustrated by (2-pyridyl)(Me3Si)-CSbCl, in which internally chlorine-bridged Sb2C2 rings are interconnected into a linear array, 157 (Sb- -Cl 3.054 A) [395], 

The anion [Ph2Sbl2] is a dimer (Sb-I 2.925 and 3.109 A) consisting of two square pyramids joined by a double Sb-I-Sb bridge [397]. 

Phenylantimony(III) dihalides, PhSbX2 (X = Cl, Br, I), have isotypical structures and are all self-assembled via secondary bonding to form two-dimensional sheets, with all the phenyl groups on the same side of the plane [400]. In these compounds Sb interactions between adjacent molecules are also present. 

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Many organoantimony(III) halides are Lewis amphoteric. They have acidic sites on the Sb atoms and they are also basic through the lone pairs of electrons on the halogen atoms. A frequently encountered consequence of this dual nature is the formation of coordination polymers in the solid state. The resulting structures formed through self-assembly of molecules were considered in a book and in a review article. The Lewis acidity of organoantimony halides is also reflected in the tendency to form stable adducts with neutral donors or with halide anions. The 1 1 adduct (2) is formed by reaction of methylantimony dichloride with 2,2 -bipyridine. " ... 

Reaction of organoantimony halides with phosphorus anions... 

From propylene oxide these catalysts yield crystalline, isotactic polymers. Living polymerizations with metalloporphyrin derivatives are difficult to terminate and are therefore called by some immortal Catalysts like (C6H5)3-SbBr2-(C2H5)3N in combination with Lewis acids also yield crystalline poly(propylene oxide). Others, like pentavalent organoantimony halides, are useful in polymerizations of ethylene oxide. 

Reactions of trimethylstibine sulfide with alkyl halides proceed smoothly under mild conditions to give dialkyl disulfides and organoantimony compounds in quantitative yields 25) ... 

Organoantimony and -bismuth(III) halides are reduced with hydride reagents at low temperatures (equations 61 , 62 , 63 and 64 °). 

Reaction of organoantimony anionic species with phosphorus and arsenic halides... 

Reaction of organoantimony and -bismuth anionic species with metal halides... 

Organoantimony(III) and -bismuth(III) compounds containing electronegative atoms such as halogen, oxygen and so on show Lewis acidic character. Thus, tetracoordinate anions and even pentacoordinate dianions have been prepared from the corresponding halides or pseudohalides, and several of the compounds have recently been fully characterized by X-ray crystallography. Several examples are shown in equations 162 , 163 , 164 , 165 , 166 , 167 , 168 and 169 ... 

Reaction of organoantimony and -bismuth halides with various oxygen nucleophiles gives the corresponding oxygen compounds. Several examples are shown in equations... 

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