Reactions of triphenylantimony with difluorobromoacetic acid in the presence of tert-butyl hydroperoxide in ether

Abstract

Oxo-bis(difluorobromoacetatotriphenylantimony) [Ph3SbOC(O)CF2Br]2O (1) was synthesized by interaction of equimolar amounts of triphenylantimony and difluorobromoacetic acid in the presence of tert-butyl hydroperoxide in ether at room temperature. Under similar conditions at the molar ratio of 1:2:1; the corresponding triphenylantimony dicarboxylate Ph3Sb[OC(O)CF2Br]2 (2) was formed. The structure of complexes 1 and 2 is proven by X-ray diffraction. Crystallographic characteristics of 1 C40H30Br2F4O5Sb2; M = 1069.96; triclinic syngony; space group P-1; cell parameters: a = 9.899(5) Å; b = 15/325(6) Å; c = 22.083(10) Å;  = 71.858(13); β = 85.93(3);  = 71.405(19); V = 3016(2) Å3; Z = 1.5; calc = 1.767 g/cm3;  = 3.391 mm–1; F(000) = 1554.0; region collection at 2q: 5.67–56.752; –13 ≤ h ≤ 13; –20 ≤ k ≤ 20; –29 ≤ l ≤ 29; total reflections 106273; independent reflections 15000 (Rint = 0.0556); GOOF = 1.019; R-factor = 0.0595]; 2 [C22H15Br2F4O4Sb; M = 700.92; monoclinic syngony; space group C2/c; cell parameters: a = 18.118(16) Å; b = 10.305(6) Å; c = 14.431(11) Å; β = 108.94(6); V = 2548(3) Å3; Z = 4; calc = 1.829 g/cm3;  = 4.272 mm–1; F(000) = 1348.0; collection area by 2q: 5.898–56.99; –24 ≤ h ≤ 24; –13 ≤ k ≤ 13; –19 ≤ l ≤ 19; total reflections 67806; independent reflections 3215 (Rint = 0.0731); GOOF = 1.556; R-factor = 0.1051]. From the X-ray diffraction data it follows that crystal 1 consists of two types of binuclear bridging molecules A and B; one of which is centrosymmetric (the inversion center is the bridging oxygen atom) and has a linear fragment Sb(1)O(1)Sb(1); in the second molecule the analogous angle Sb(2)O(4)Sb(3) is 141.6(2)°; while the lengths of the SbObrid bonds [1.9368(9)1.971(4) Å] are significantly shorter than the terminal SbOterm bonds (2.209(5)2.233(5) Å). The antimony atoms in 1 and 2 have a distorted trigonal-bipyramidal coordination with the oxygen atoms in axial positions [OSbO 176.7(5) Å for 2] and equatorial SbC bond lengths 2.079(4)2.108(6) Å. In the linear centrosymmetric molecule 1A there are coordination bonds of the central metal atom with the carbonyl oxygen atom [Sb∙∙∙O=C 3;450(9) Å]; while in the iso-curved molecule 1B such coordination is observed only for one carbonyl group [3.302(8) Å]. The antimony atoms in the centrosymmetric molecule 2 (the inversion center is the antimony atom) have a distorted trigonal-bipyramidal coordination with the oxygen atoms of the carboxyl groups in the axial positions [OSbO 176.7(5); SbO 2.100(11) Å] and the equatorial phenyl ligands [SbC 2.097(16); 2.110(6) Å]. Due to the bidentate nature of the carboxylate ligands in structure 2; there are intramolecular contacts between the Sb and O atoms of the carbonyl groups [3.174(7) Å]. The formation of intramolecular contacts Sb⋅⋅⋅O(=C) in 2 occurs within two CSbC equatorial angles; as a result; the CSbC equatorial angles differ slightly from each other [117.0(5); 121.5(2); 121.5(2)]. Complete tables of atomic coordinates; bond lengths; and valence angles of compounds 1 and 2 have been deposited at the Cambridge Crystallographic Data Centre (CCDC 2217059 and 2084130; deposit@ccdc.cam.ac.uk; http://www.ccdc.cam.ac.uk).