Reactions of Pentaphenyl- and Penta(para-tolyl)antimony with Ferrocenedicarboxylic Acid

Abstract

Interaction of pentafluorophenyl- and penta(para-tolyl)antimony with ferrocenedicarboxylic acid (molar ratios 1 : 1 and 2 : 1) in toluene (20°C, 24 h) results in the substitution of hydrogen in one or two carboxylate groups, leading to the formation of ferrocenecarboxylates of tetraaryl antimony HOOCС₅H₄FeС₅H₄C(O)OSbPh₄ (1), HOOCС₅H₄FeС₅H₄C(O)OSbTol₄ (2), Ph₄SbC(O)OС₅H₄FeС₅H₄C(O)OSbPh₄ (3) and p-Tol₄SbC(O)OС₅H₄FeС₅H₄C(O)OSbTol₄ (4) with yields up to 83%. Compounds 1−4 were identified by elemental analysis, IR spectroscopy, and X-ray diffraction analysis for 4. The XRD analysis of complex 4 was conducted on an a D8 Quest Bruker automatic four-circle diffractometer (Мо K_α radiation, λ = 0,71073 Å, graphite monochromator) at 293 K. Crystallographic characteristics of 4: monoclinic syngony, space group P2₁/c, a = 17.227(17) Å, b = 11.064(9) Å, c = 30.59(3) Å, β = 100.00(4)°, V = 5742(9) ų, Z = 4, ρ_calc = 1.440 g/cm³, 2θ 6.02°−49.08°, 124 343 total reflections, 9436 independent reflections, number of refined parameters 684, R_int = 0.1051, GOOF 1.094, R₁ = 0.0536, wR₂ = 0.1309, residual electron density (max/min) 0.88/–1.21 e/ų. According to XRD analysis, the coordination of antimony atoms in crystal 4 is distorted octahedral due to the bidentate chelating nature of the carboxylate ligand. Diagonal angles in the two octahedra are 146.4(2)°, 154.0(3)°, 171.0(2)° and 147.4(2)°, 154.8(2)°, 166.9(2)°. The Sb−О distances are 2.296(5), 2.502(5) Å and 2.289(5), 2.453(5) Å, while the Sb−С bonds differ significantly, 2.146(7)−2.166(7) and 2.123(6)−2.165(7) Å. The structural organization of the crystal is mainly governed by С−Н···π interactions.