Element-Element-Bindungen. II. Synthese und Struktur eines anellierten Tetrastibaadamantans,dargestellt aus Antimon(III)-chlorid und Natrium-cyclopentadienid

Element-Element Bonds. II. Synthesis and Structure of an Anellated Tetrastibaadamantane, Formed by Antimony(III) Chloride and Sodium Cyclopentadienide Revising the reaction between antimony(III) chloride and sodium cyclopentadienide in tetrahydrofuran (THF), originally published by FISCHER und SCHREINER 3], we could not verify the stated formation of tetra(cyclopentadienyl)distibane being red both in the solid and in solution. The pale yellow compound isolated instead is sodium 18-cyclopenta-2,4-dienyl-4,8,12-cyclopenta-2,4-diene-1,1,2-triyl-3a,8a-epistibino-tricyclopenta1,4,7]tristiboninide] = 3 tetrahydrofuran 1 . Shown by an x-ray crystal structure determination (?45°C; monoclinic; Cc; a = 1882.7(9); b = 1183.5(5); c = 1733.8(13) pm; β = 93.38(5)°; Z = 4; R = 0.043) three (μ₃-C₅H₃) units together with four antimony atoms build up a tetrastibaadamantane framework with a (σ-C₅H₅) and a (μ₂-C₅H₃^?) group as additional substituents. Nearly centric above the anionic ring a sodium cation coordinated by three THF molecules is placed. Characteristic bond lengths and angles lie in the following ranges: Sb? C(sp²) 212–216; Sb? C(sp³) 216–228; Na? C 270–284; Na? O 226–235 pm; C? Sb? C 91–97; Sb? C? Sb 109–110°. ¹H and ¹³C-{¹H} n.m.r. spectra are discussed; the ion pair 1 shows a degenerate valency tautomerism in solution.