ALKYLALUMINUM DERIVATIVES OF 2-THIOPHENEMETHANOL AND 2-FURANMETHANOL - MOLECULAR-STRUCTURE OF A NOVEL ORGANOALUMINUM COMPOUND, ([(ME2AL)3(MU-OCH2-2-C4H3S)6]AL), CONTAINING 4-COORDINATE AND 6-COORDINATE ALUMINUM CENTERS

The reaction of trialkylaluminum derivatives, R3Al (R = Me or Et), wit h alcohols such as 2-thiophenemethanol or2-furanmethanolyields {[(R2M3 (mu-OCH2-2-C4H3E)6]M} (M = Al; E = S, R = Me (1a), Et (1b); E = 0, R = Me (2) and the corresponding alkane, RH, in high yields. The resultin g complex metal alkoxides have been characterized by H-1 and C-13 NMR spectroscopy. The structure of la was determined by single crystal X-r ay diffraction techniques. la was assigned to the orthorhombic cell sy stem, space group Pbcn (No. 60), with cell constants a = 18.153(2) ang strom, b = 11.176(2) angstrom, c = 22.820(2) angstrom, and Z = 4. The structure was refined to a final R = 5.99% (R(w) = 5.39%) based on 142 2 (I(o) greater-than-or-equal-to 2.5sigma(I)) observed reflections. Th e central core of {[(Me2Al)3(mu-OCH2-C4H3S)6] Al} contains an octahedr al aluminium (III) bound through six bridging alkoxide units to three organoaluminium Me2Al- moieties. In solution, the methylene protons of the 2-thiophenemethoxide ligand in la and the 2-furanmethoxide ligand in 2 are diastereotopic, and the full spectrum is consistent with the solid state structure. The room temperature IH NMR spectra of compoun d lb is also consistent with this structure but show the additional fe ature of diastereotopic CH2 groups in the ethyl moiety.