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The title compound is prepared from naphthazarine (5,8-dihydroxy-1,4-naphthoquinone) and tetraphenylstibonium ethoxide (molar ratio 1:2) in dioxane as a solvent. X-ray analysis shows the naphthazarine dianion to act as a bifunctional chelating ligand in which two 2,2′-connected 1,3-diketonato groups are fixed in a coplanar position by two cis-ethenediyl bridges. The interaction of the naphthazarine dianion with the tetraphenylstibonium ions is an intermediate between ionic and covalent bonding. Consequently the antimony ions have strongly distorted octahedral coordination spheres (Sb–O 225,5(4) pm, Sb–C e  215,9(6) pm, Sb–C a  214,8(5) pm; O-Sb-O 75,9(1)°, C e – Sb– C e  103,8(2)°, C a –Sb–C a  166,0(2)°). The chelate rings are folded at the O/O axes (angles of fold 20-36°), the two antimony centers being arranged in trans-positions relative to the plane of the naphthazarine dianion.

zeitschrift für naturforschung b

μ-5,8-Dioxido-1,4-naphthochinon(2–)-O,O″′; O′,O″ ]bis-[tetraphenylantimon(V)]-Dioxan (3/5) / [,u-5,8-Dioxido-l,4-naphthoquinone(2–)-O,O″′; O′,O″]bis[tetraphenylantimony(V)] Dioxane (3/5)