Octahedral geometry antimony

Figure 8.27 The Sb2Fn ion in which there is a bridging fluorine linking two SbFs groups, each antimony having an approximately octahedral geometry.

A dimeric structure proposed by Meinema and Noltes for dialkylantimony(V) methoxides has been confirmed by recent Mossbauer studies of R2Sb(OMe)3277). Compounds have octahedral geometry around antimony atoms with methoxo bridges. 

Results of Meinema et al.351) also get support from the X-ray analysis of MeSb-(acac)Cl3355,356. The crystals belong to a tetragonal system in which the methyl group occupies the basal plane. Antimony acquires a slightly distorted octahedral geometry... 

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]. 

Diphenyl(phenylthiolato)antimony, PhjSbSPh, forms an octahedral molybdenum tricarbonyl complex. Mo(CO)3(Ph2SbSPh), with/ac-geometry and the ligands attached via antimony atoms (mean Sb—Mo 2.74 A, Sb—Mo—Sb 91.6-93.3°) rather than sulphur . Antimony-sulphur distances (mean 2.43 A) are normal. 

Diphenylantimony tribromide and acetonitrile form a weak 1 1 complex and, in keeping with the observation that the solvent molecule is readily lost even at room temperature, there is a long Sb N contact (2.53 A) The antimony geometry is distorted octahedral with phenyl groups occupying trans positions the Sb—Br bond trans to acetQnitrile is substantially shorter (2.519 A) than those trans to each other (2.605 A). 

Alkoxides of Sb(III) or Sb(V) with known structures are compounds of the types Sb(0R)3 (3) and Sb(0R)5 (4). They are both dimeric in the solid state, with bridging alkoxy groups and trigonal pyramidal geometry or octahedral coordination about antimony. 

Antimony pentafluoride is tetrameric in the solid phase and trimeric in the gas phase. The trimer consists of a somewhat buckled ring of alternating Sb and bridging fluorine atoms. See Fig. 16.12. The coordination geometries of the Sb atoms are distorted octahedral. 

Only one value is reported for antimony compounds having a symmetry other than octahedral or tetrahedral SbCls resonates at -1-509 ppm, but the line width is about 8000 Hz. This very broad absorption band illustrates the effect on the rate of quadrupolar relaxation as the geometry around the antimony nucleus is reduced from or to trigonal bipyramidal (Csv). 

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