Tris(4-Fluorophenyl)Antimony Dicarboranylcarboxylates

Abstract

Tris(4-fluorophenyl)antimony bis(2-methylcarboranylcarboxylate) (1) and bis(carboranylcarboxylate) (2) were obtained by the oxidative addition reaction between tris(4-fluorophenyl)antimony, carborane-containing carboxylic acid and tertiary butyl hydroperoxide in diethyl ether with high yield. The compound has been identified by NMR, IR spectroscopy and X-ray diffraction analysis. According to the X-ray diffraction analysis the target product 1 is a benzene solvate. The antimony atom in the molecules of compounds 1 and 2 has a distorted trigonal-bipyramidal coordination with the oxygen atoms of carboxylate ligands in the axial positions. The Sb–C bond lengths intervals are 2.086(4)–2.110(3) Å (1), 2.083(5)–2.103(5) Å (2). The Sb–O bonds are equal to 2.116(3), 2.130(3) Å (1) and 2.124(5), 2.111(4) Å (2). The Sb–C distances are shorter than the Sb–O distances, which is typical for the previously structurally characterized triarylantimony dicarboxylates. The values of CSbC individual angles are 115.97(15)°, 116.70(14)°, 127.32(15)° (1) and 113.9(2)°, 114.5(2)°, 131.6(2)° (2). Significant increase in one of the angles is associated with the cis-conformation of the carboxylate ligands relatively to the equatorial plane. The OSbO axial angles are 172.66(10)° (1) and 175.75(14)° (2). The conformation of the aryl ligands with respect to the equatorial plane [C₃] is a propeller. The structures of tris(4-fluorophenyl)antimony dicarboranylcarboxylates contain intramolecular contacts between the antimony atoms and the oxygen atoms of carboxylate ligands. The Sb···O=С distances are 3.349(3), 3.237(3) Å (1); 3.284(6), 3.316(7) Å (2), which is less than the sum of the van der Waals radii of antimony and oxygen atoms (3.70 Å). The formation of a spatial network in crystals of compounds 1 and 2 is due to the presence of weak hydrogen bonds involving boron atoms of carboxylate ligands and fluorine atoms of aryl ligands: F···Н (2.49 Å), B···Н (3.18 Å) (1) and F···Н (2.29 Å), B···Н (3.18 Å) (2). Complete tables of coordinates of atoms, bond lengths and valence angles are deposited at the Cambridge Structural Data Bank (No. 1880056 for 1; No. 1919919 for 2; deposit@ccdc.cam.ac.uk; http:// www.ccdc.cam.ac.uk/data_request/cif).