Formation of onium compounds of antimony in oxidative addition reactions

The interaction of tris(3-trifluoromethylphenyl)antimony with 2,4-dimethylbenzenesulfonic acid in the presence of tert-butyl hydroperoxide (molar ratio 1:2:1) in ether yielded 12% tetrakis(3-trifluoromethylphenyl)antimony 2,4-dimethylbenzenesulfonate (1), which was identified by IR spectroscopy and X-ray structural analysis. The X-ray diffraction analysis was performed on a Bruker D8 QUEST diffractometer. The crystallographic characteristics of the unit cell of the compound are as follows: monoclinic space group P21/c, a = 12.160(8), b = 14.561(11), c = 21.755(14) Å, β = 97.333(18), V = 3821(5) Å3, Z = 4, ρcalc = 1.543 g/cm3, m = 0.869 mm-1, F(000) = 1760, crystal size 0.56´0.15´0.1 mm, data collection range for 2θ, deg: 6.06-49.28, index range -14 ≤ h ≤ 12, -17 ≤ k ≤ 17, -25 ≤ l ≤ 25, the number of measured reflections is 23742, the number of independent reflections is 6398, Rint = 0.0828, GOOF = 1.017, the number of parameters is 480, R1 = 0.0568, wR2 = 0.1414. According to the X-ray diffraction data, the antimony atoms in the compound have a distorted trigonal bipyramidal coordination with the oxygen atom of the sulfonate group in axial position. The CSbO axial angle is 174.08(18)º. The sum of the CSbC equatorial angles is 352.8(2)º, the Sb-Ceq distances [2.121(6), 2.121(6), 2.122(6) Å] are significantly shorter than the Sb-Cax [2.129(7) Å] and Sb-O [2.463(4) Å] bond lengths. Complete tables of atomic coordinates, bond lengths, and bond angles have been deposited with the Cambridge Crystallographic Data Center (No. 2417629; deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/cif).