Hexamethyl-1,2,3-tristanna-[3]ferrocenophane – Molecular Structure and Cleavage of the Tin–Tin Bonds by Iodine, Sulfur, Selenium, and Tellurium

Abstract

Hexamethyl-1,2,3-tristanna-[3]ferrocenophane (1) was prepared by the reaction of 1,1′-bis(dimethylstannyl)ferrocene (3) with bis(diethylamino)dimethylstannane. The molecular structure of 1 was determined by X-ray crystallography. The monoclinic unit cell (space group P21/c; a = 18.659(4), b = 17.311(3), c = 13.719(3) A; β = 111.02(3)°) contains two independent molecules which differ slightly in their conformation. The cyclopentadienyl rings are almost parallel, but the positions of the substituted carbon atoms are twisted by τ £ 62° with respect to the ecliptic positions. The reactivity of 1 towards iodine and chalcogens E (E = S, Se, Te) was studied. Iodine reacts to give 1,1′-bis[iodo(dimethyl)stannyl]ferrocene (6) and dimethyltin diiodide. In the case of the chalcogens, the detectable and isolated products are 1,3-distanna-2-chalcogena-[3]ferrocenophanes (E = S (7), Se (8), Te (9)) in addition to trimeric dimethyltin chalcogenides, (Me2SnE)3. Crystals suitable for X-ray structural analysis could be obtained of 1,3-distanna-2-thia-[3]ferrocenophane (7); the triclinic unit cell (space group P 1) has the dimensions a = 6.538(2), b = 9.013(2), c = 15.442(2) A; α = 92.15(2), β = 91.89(2), γ = 109.43(2)°. The molecular structures of 1 and 7 are compared with those of other 1,3-distanna-[3]ferrocenophanes. All compounds were studied by NMR spectroscopy (1H, 13C, 77Se, 119Sn and 125Te NMR) in order to establish the presence of the [3]ferrocenophanes 7–9 and of the cycles (Me2SnE)3 in solution.