Synthesis and structure of fluorinated tetraphenylantimony β-diketonates

Abstract

The reactions of pentaphenylantimony with fluorinated β-diketones have been studied. The structure of the obtained compounds has been determined by the X-ray diffraction method and confirmed by IR, 1H, 13C and 19F NMR spectroscopy. According to X-ray diffraction analysis data, the reaction products are tetraphenylantimony 1,1,1-trifluoropentane-2,4-dionate (3а), 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionate (3b) and 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyloctane-3,5-dionate (3c): Ph4Sb[OC(R)CHC(R')O] (R = CH3 (3a), Bu-t (3b, 3c); R' = CF3 (3a, 3b), C3F7 (3c)), the antimony atoms in the molecules have a distorted octahedral coordination. The CSbC angles equal 158.26(14)°, 157.90(9)°, 157.75(15)° (3 a‒c), the CSbO angles are 164.70(12)°, 168.05(12)° (3a); 165.47(9)°, 167.37(7)° (3b); 164.96(14)°, 169.66(13)° (3c). The Sb–C bond lengths vary in the ranges of 2.142(4)–2.164(4) Å, 2.144(2)–2.160(2) Å, 2.142(4)–2.160(4) Å (3 a‒c), the Sb–O distances are 2.358(3), 2.333(3) Å (3a); 2.306(2), 2.339(2) Å (3b); 2.376(3), 2.289(3) Å (3c). The 3a and 3b13C NMR spectra contain short spin-spin interactions between carbon and fluorine atoms with a large direct spin-spin coupling constant, 1JCF ≈ 286.0 Hz, which are characteristic for fluorinated compounds.