THE SYNTHESIS OF NEW THIOLATO BRIDGED-IRON CARBONYL-COMPLEXES

The reagent [Me2SSMe]BF4 has been shown to function as MeS+ donor in organometallic synthesis. Here we report reactions of this species and also reactions of the related species [Me2SSR]BF4 (R = Ph, tol) with Fe2(mu-X)(mu-Y)(CO)4(L)2 (X, Y = SMe, SPh, Stol, PMe2; L = PMe3, PPhMe2, PPh2Me) to give [Fe2(mu-X)(mu-Y)(mu-SR)(CO)4(L)2]BF4. This is the first use of the reagents, [Me2SSR]BF4 (R = Ph, tol), as SR+ donors in organometallic synthesis. The regiospecific addition of the SR+ group trans to the phosphine ligands in the precursor was exploited in the synthesis of isomeric species with the formula [Fe2(mu-SMe)2(mu-SPh)(CO)4(PMe3)2]BF4. The H-1 NMR spectra of certain products with bridging SPh and Stol groups indicated the presence of two species, assumed to be conformers differing by the orientation of the organic group. Steric factors are thought to control this structure feature. Reactions between [Me2SSMe]BF4 and either e,e- or a,e-Fe2(mu-SMe)2(CO)6 (separable conformers that differ by the orientation of the methyl groups) result in formation of [Fe2(mu-SMe)3(CO)6]BF4. From both reactions, only the more symmetric conformer (C3 symmetry) can be isolated. An H-1 NMR study indicated that the reaction proceeded through an intermediate, possibly [(CO)3(SMe)Fe(mu-SMe)2Fe(NCMe)(CO)3]BF4. A single-crystal X-ray diffraction study of [Fe2(mu-SMe)3(CO)4(PPhMe2)2]-BF4 is reported. Crystal data: space group P21/c; a = 14.032 (6) angstrom, b = 11.935 (5) angstrom, c = 18.494 (6) angstrom, beta = 101.58 (6)-degrees, V = 3034 (2) angstrom 3, D(calc) = 1.594 g/cm3, Z = 4, R = 0.0970, R(w) = 0.0482 for 2458 independent reflections with F greater-than-or-equal-to 4-sigma-(F) and 2-theta less-than-or-equal-to 55.0-degrees.