HEXAMETHYL-1,2,3-TRISTANNA-[3]FERROCENO - MOLECULAR-STRUCTURE AND CLEAVAGE OF THE TIN-TIN BONDS BY IODINE, SULFUR, SELENIUM, AND TELLURIUM

Hexamethyl-1,2,3-tristanna-[3]ferrocenophane (1) was prepared by the r eaction of 1,1'-bis(dimethylstannyl)ferrocene (3) with bis(diethylamin o)dimethylstannane. The molecular structure of 1 was determined by X-r ay crystallography. The monoclinic unit cell (space group P2(1)/c; a=1 8.659(4), b=17.311(3), c=13.719(3) Angstrom; beta=111.02(3)degrees) co ntains two independent molecules which differ slightly in their confor mation. The cyclopentadienyl rings are almost parallel, but the positi ons of the substituted carbon atoms are twisted by tau approximate to 62 degrees with respect to the ecliptic positions. The reactivity of 1 towards iodine and chalcogens E (E = S, Se, Te) was studied. Iodine r eacts to give 1,1'-bis[iodo (dimethyl)stannyl] ferrocene (6) and dimet hyltin diiodide. In the case of the chalcogens, the detectable and iso lated products are 1,3-distanna-2-chalcogena-[3] ferrocenophanes (E = S (7), Se (8), Te (9)) in addition to trimeric dimethyltin chalcogenid es, (Me2SnE)(3). Crystals suitable far X-ray structural analysis could be obtained of 1,3-distanna-2- thia-[3]ferrocenophane (7); the tricli nic unit cell (space group P (1) over bar) has the dimensions a=6.538( 2), b=9.013(2), c = 15.442(2) Angstrom; alpha=-92.15(2). beta=91.89(2) , gamma=109.43(2)degrees. The molecular structures of 1 and 7 are comp ared with those of other 1,3-distanna-[3]ferrocenophanes. All compound s were studied by NMR spectroscopy (H-1, C-13, Se-77, Sn-119 and Te-12 5 NMR) in order to establish the presence of the ferrocenophanes 7-9 a nd of the cycles (Me2SnE)(3) in solution.