Synthesis and structure of tris(2-methoxy, 5-chlorinephenyl)antimony dicarboxylates

The interaction of tris (2-methoxy,5-chlorophenyl)antimony with a carboxylic acid in the presence of tert -butylhydroperoxide (1:2:1 mol.) in ether proceeds according to the oxidative addition reaction scheme with the formation of tris (2-methoxy,5-chlorophenyl)antimony dicarboxylates [(MeO-2)(Cl-5)C6H3]Sb[OC(O)R]2 (R = CH2Cl (1), CH2CH2Ph (2), CºCH (3), CºCPh (4)). The IR spectra of compounds 1-4, 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, the crystallographic parameters of the unit cell of compound 1: crystal size 0.26 ´ 0.12 ´ 0.06 mm, space group P-1, а = 9.64(2), b = 11.90(3), c = 15.00(3) Å, α = 108.05(11)°, β = 95.03(9), γ = 112.48(5)°, V = 1469(5) Å3, ρ = 1.658 g/cm3, Z = 2; for crystal 2: 0.47 ´ 0.2 ´ 0.18 mm, P-1, а = 11.987(5), b = 14.342(7), c = 14.96(6) Å, α = 63.267(16)°, β = 73.004(14), γ = 81.60(3)°, V = 2197.3(17) Å3, ρ = 1.395 g/cm3, Z = 2; for crystal 3: 0.49´0.42´0.33 mm, P-1, а = 15.209(16), b = 15.912(14), c = 16.080(13) Å, α = 87.90(3)°, β= 64.84(3), γ = 86.96(5)°, V = 3517(6) Å3, ρ = 1.440 g/cm3, Z = 2; for crystal 4: 0.36 ´ 0.21 ´ 0.11 mm, P 21/ с , а = 13.539(6), b = 16.807(11), c = 19.749(8) Å, α = 90.00°, β= 109.665(12), γ = 90.00°, V = 4232(4) Å3, ρ = 1.436 g/cm3, Z = 4. The antimony atoms in 1-4 have a distorted trigonal-bipyramidal coordination with carboxylate ligands in axial positions. The OSbО angles are 176.67(14)°, 174.88(5)°, 173.59(15)° (174.22(14)°), 172.61(6)°, the sum of the СSbC angles in the equatorial plane are 360°, the axial Sb-O bonds that equal (2.121(5), 2.125(5) Å (1), 2.085(1),2.097(1) Å (2), 2.087(4)-2.137(4) Å (3), 2.1109(17), 2.1017(17) Å (4)) and the equatorial Sb-С bonds that equal (2.104(7)-2.120(6) Å (1), 2.110(2)-2.120 (2) Å (2), 2.075(6)-2.133(6) Å (3), 2.108(3)-2.115(2) Å (4)) are close to the sum of the covalent radii of the atoms. Intramolecular distances Sb∙∙∙O=С (3.018(3), 3.179(3) Å (1), 3.098(3), 3.135(3) Å (2), 3.204(3)-3.220(5) Å (3), 3.129(3), 3.158 (3) Å (4)) and Sb∙∙∙OMe (3.127(3)-3.161(3) Å (1), 3.077(3)-3.210(3) Å (2), 3.136(3)-3.172(3) Å (3), 3.139(3)-3.186(3) Å (4)) are much smaller than the sum of the van der Waals radii of atoms.