SYNTHESIS, SOLID-STATE STRUCTURE, AND REDUCTION OF 1,1-DICHLORO-2,3,4,5-TETRAMETHYLSILOLE

The previously unknown oro-2,3,4,5-tetramethyl-1-silacyclopenta-2,4-di ene (3) was prepared in a three-step synthesis starting from zirconoce ne dichloride, 2-butyne, and n-butyllithium via -2,3,4,5-tetramethyl-1 -zirconacyclopenta-2,4-diene (1) and 1,4-diiodo-1,2,3,4-tetramethylbut a-1,3-diene (2). 3 was characterized by NMR spectroscopy and single-cr ystal X-ray diffraction. Reaction of the new silole 3 with 4 equivalen ts of lithium in THF gives the corresponding dianion 4. H-1-, C-13-, a nd Si-29-NMR chemical shifts of 4 compared with 3 indicate some aromat ic character for the ionic species. Trapping of 4 with Me(3)SiCl gives 1,1-bis(trimethylsilyl)-2,3,4,5-tetramethylsilole (5) in quantitative yield.