Synthesis and Structure Features of Tetraphenylantimony 2,3-Difluoro- and 2,3,4,5,6-Pentafluorobenzoate

Abstract

Tetraphenylantimony 2,3-difluorobenzoate (1) and tetraphenylantimony 2,3,4,5,6-pentafluorobenzoate (2) was obtained by the interaction of pentaphenylantimony with 2,3-difluorobenzoic and 2,3,4,5,6-pentafluorobenzoic acids in benzene with a yield of up to 98 %. The compounds were also synthesized by the ligand redistribution reaction between pentaphenylantimony and triphenylantimony dicarboxylates. The compounds have been identified by IR spectroscopy and X-ray diffraction analysis. According to the X-ray diffraction data, the antimony atoms in compounds 1 and 2 have a distorted trigonal-bipyramidal coordination with the oxygen atom in axial positions. X-ray diffraction analysis was performed on a D8 QUEST diffractometer (Bruker). The crystallographic parameters of the unit cell of the compounds: 1 space group Р1 ̅, а = 9.857(5), b = 10.154(7), c = 14.362(11) Å, α = 83.74(4)°, β = 82.59(3), γ = 68.34(2)°, V = 1321.9(16) Å3, ρcalc = 1.475 g/cm3, Z = 2; 2 space group Р21/с, а = 16.186(9), b = 8.771(6), c = 20.413(13) Å, α = 90.00°, β = 113.073(17), γ = 90.00°, V = 2666(3) Å3, ρcalc = 1.597 g/cm3, Z = 4. The OSbO axial angles are slightly different and amount to 177.90(5)º in 1 and 179.00(5)º in 2. The sums of the CSbC equatorial angles are 356.89(9)º (1), 355.85(7)º (2). The Sb–Ceq distances in compounds 1 and 2 are 2.116(2), 2.119(2), 2.118(2) and 2.1073(17), 2.1158(18), 2.1152(19) Å respectively, which are significantly shorter than the Sb–Сax bond lengths (2.169(2) and 2.1617(19) Å). The organization of molecules in the crystals of compounds is due to hydrogen bonds and CHπ-interactions of the aryl and carboxyl ligands. The main difference between structures 1 and 2 is the different Sb–O bond lengths (2.2864(18) and 2.3168(18) Å), which is due to an increase in the electronegativity of the carboxyl ligand in 2, caused by the presence of five electronegative fluorine atoms in the benzoate substituent. Complete tables of atom coordinates, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Center (No. 1980908 (1); 1977189 (2); deposit@ccdc.cam.ac.uk; http://www.ccdc.cam.ac.uk/data_request/cif).