The oxidative addition reaction of tris(2-methoxy-5-chlorinephenyl)antimony with trifluoropropionic acid

The interaction of tris (2-methoxy-5-chlorophenyl)antimony with 3,3,3-trifluoropropionic acid in the presence of hydrogen peroxide (1:2:1 mol) in ether proceeds according to the oxidative addition reaction scheme with the formation of bis (3,3,3-trifluoropropionyl) tris (2-methoxy-5-chlorophenyl)antimony [(MeO-2)(Cl-5)C6H3]Sb[OC(O)CH2F3]2. The IR spectra of compound 2, recorded on a Shimadzu IRAffinity-1S Fourier transform IR spectrometer in a KBr pellet in the region of 4000-400 cm-1, contain absorption bands of carbonyl groups, which are shifted to the low-frequency vibration region in comparison with the IR spectra of the initial acids. According to the X-ray diffraction data obtained on a Bruker D8 QUEST diffractometer, compound 1 has the following crystallographic parameters of the unit cell: crystal size 0.23×0.21×0.08 mm3, space group P21/n, а = 8.883(7), b = 21.184(15), c = 13.642(15) Å, α = 90.00°, β = 107.34(3)°, γ = 90.00°, V = 2451(4) Å3, ρcalc = 1.587 g/cm3, Z = 4; crystal 2 has the following crystallographic parameters of the unit cell: 0.3×0.25×0.08 mm3, P21/c, а = 12.00(5), b =16.81(7), c =16.30(9) Å, α =90.00°, β =108.3(3)°, γ =90.00°, V =3121(25) Å3, ρ calc = 1.704 g/cm3, Z = 4. The antimony atom in 2 has a distorted trigonal-bipyramidal coordination with carboxylate ligands in axial positions. The OSbО angles are 174.2(5)°, the sums of the СSbC angles in the equatorial plane are 360°, the axial Sb-O bonds equal 2.073(15), 2.092(15) Å, and the equatorial Sb-С bonds equal 2.05-2.13 Å, which is close to the sum of the covalent radii of the atoms. The intramolecular Sb∙∙∙OМе distances (3.035(3), 3.037(3), 2.992(4) Å (1), 3.03(2), 3.119(17), 3.147(19) Å (2)), as well as Sb∙∙∙OMe for compound 2 (3.232(19), 2.99(2) Å), are much smaller than the sum of the van der Waals radii of atoms.