Synthesis and structure of tris(4-trifluoromethylphenyl)antimony derivatives
Authors:   South Ural State University, Chelyabinsk, Russian Federation, Sharutin V. , Senchurin V. , Trotsenko D. 
Published: November 2023

Interaction of tris(4-trifluoromethylphenyl)antimony (1) with copper(II) chloride and copper(II) bromide in acetone has been used to synthesize tris(4-trifluoromethylphenyl)antimony dichloride (2) and dibromide (3), yielding 85 % and 92 %, respectively. Oxidation of 1 by tert-butyl hydroperoxide in the presence of 2,5-difluorobenzoic acid (mole ratio 1:1:2) in ether is accompanied by the formation of tris(4-trifluoromethylphenyl)antimony bis(2,5-difluorobenzoate) (4), yielding 81%. Compounds 1–4 have been identified by IR spectroscopy and X-ray diffraction analysis. According to the X-ray analysis data, obtained on an automatic D8 Quest Bruker diffractometer (Mo K-radiation, λ = 0.71073 Å, graphite monochromator) at 293 K, for crystals 1 [C21H12F9Sb, M 557.06, symmetry group Р–1; cell parameters: a = 10.858(13) Å, b =11.072(13) Å, c = 11.432(18) Å, α = 104.91(7) degrees, β = 113.61(5) degrees, γ = 106.89(5) degrees; V = 1090(3) Å3; the crystal size is 0.34  0.33  0.3 mm; intervals of reflection indexes are 14  h  14, 15  k  15, 15  l  15; total reflections 40268; independent reflections 5862; Rint 0,0477; GOOF 1.049; R1 = 0.0533, wR2 = 0.1427; residual electron density 1.16/1.04 e/Å3], 2 [C21H12F9Cl2Sb, M 627.98, symmetry group Р–1; cell parameters: a = 7.920(4) Å, b = 14.732(7) Å, c = 21.759(13) Å, α = 75.31(2) degrees, β = 86.12(3) degrees, γ = 76.10(2) degrees; V = 2384(2) Å3; the crystal size is 0.650.150.11 mm; intervals of reflection indexes are 11  h  11, 21  k  22, 32  l  32; total reflections 138621; independent reflections 12076; Rint 0.0553; GOOF 1.109; R1 = 0.0429, wR2 = 0.0960; residual electron density 1.28/1.06 e/Å3], 3 [C27H18Br2F9Sb, M 794.98, symmetry group Р–1; cell parameters: a = 9.129(8) Å, b = 12.120(8) Å, c = 14.454(14) Å, α = 76.41(3) degrees, β = 85.93(5) degrees, γ = 68.69(3) degrees; V = 1448(2) Å3; the crystal size is 0.490.490.31 mm; intervals of reflection indexes are 12  h  12, 16  k  16, 19  l  19; total reflections 64492; independent reflections 7337; Rint 0.0545; GOOF 1.014; R1 = 0.0366, wR2 = 0.0817; residual electron density 0.68/0.61 e/Å3], and 4 [C35H18F13O4Sb, M 871.27, symmetry group Р–1; cell parameters: a = 11.575(14) Å, b = 12.017(17) Å, c = 15.041(16) Å, α = 76.33(5) degrees,β = 69.62(5) degrees, γ = 64.04(6) degrees; V = 1755(4) Å3; the crystal size is 0.31  0.12  0.11 mm; intervals of reflection indexes are 15  h  14, 15  k  15, 19  l  19; total reflections 44416; independent reflections 8033; Rint 0.0393; GOOF 1.072; R1 = 0.0326,wR2 = 0.0798; residual electron density 1,03/0,57 e/Å3], the antimony atoms in 1 have a trigonal pyramidal coordination, in 24 they have a trigonal bipyramidal coordination with electronegative ligands in axial positions. The Sb–C bond lengths in 1 are 2.155(5), 2.164(6), and 2.170(5) Å, the CSbC bond angles are 95.04(18), 95.70(17), and 97.20(18) degrees, which is less than the value of the tetrahedral angle; this is explained by the presence of a lone electron pair on the antimony atom. The C–F bond lengths vary in the range of 1.143(12)–1.334(11) Å. Crystals 2 consist of two types of crystallographically independent molecules, the geometrical parameters of which differ slightly from each other. Compound 3 is (4-CF3C6H4)3SbBr2 ∙ PhH solvate. In crystal 4, antimony atoms are coordinated by the oxygen atoms of bidentate carboxylate ligands (the Sb–O and Sb∙∙∙O=C distances are 2.120(3), 2.144(3), and 2.829(5), 2.911(6) Å, respectively).