Synthesis and structure of a tri-p-tolylantimony derivative of glycolic acid

Interaction of tri- p -tolylantimony with tert -butylhydroperoxide and glycolic acid (1:1:2) led to 2,2,2-tri- p -tolyl-1,3-dioxa-2λ5-stibolan-4-one in 75% yield. Its structure was evaluated by NMR and X-ray methods. Unlike the previously described similar reaction of triphenylantimony with hydrogen peroxide and lactic acid, during this reaction it is a cyclometallic compound that is formed, and not the corresponding dicarboxylate, which becomes obvious from the spectrum pattern, in which there is no signal of the hydroxyl group. The C23H23O3Sb crystals are described by the rhombic symmetry group Pbca with cell parameters: a = 15.01871(11), b = 15.37651(11), c = 17.04701(12) Å, Z = 8. Using the structural parameter τ, it has been concluded that the coordination of the antimony atom in this organometallic compound is close to trigonal-bipyramidal (according to the X-ray data, τ = 0.77). The XRD data, including the coordinates of atoms, bond lengths and valence angles, are deposited in the Cambridge Structural Database (CCDC 2370604).