MANGANESE THIOPHENE TRICARBONYL COMPLEXES - NUCLEOPHILIC-ADDITION TO SULFUR AND SYNTHESIS OF THIOPHENIUM SALTS

New thiophene manganese derivatives, [(2-R-1-C4H3S)Mn(CO)(3)](+) 1(sil ) (R-1 = Si(OCH2-CH2)(3)N) and 1(Mn) (R-1 = (C6H6)Mn(CO)(3)), have bee n synthesized and their reaction with nucleophiles studied. Except for the Grignard reagent, nucleophiles (Nu(-) = H-, -CN, P-(O)(OR)(2) (R = Me, Ph)) usually attack the C5 position. Grignard reagents attack th e sulfur atom to yield manganese S-R-thiophene carbonyls 3. To compare the reactivities of 1(sil) and 1(Mn) with that of (thiophene)Mn(CO)(3 )(+) with respect to Grignard reagent addition, the known compounds [( thiophene)Mn(CO)(3)](+) (thiophene = thiophene, 2-methylthiophene, 2,5 -dimethylthiophene) have been synthesized and their reaction with Grig nard reagents studied. In all cases, S-R-thiophene manganese carbonyls 3 were obtained as a sole product. Refluxing 3 (R = Ph, p-tolyl, 2-th ienyl) with Me3NO in benzene yielded diaryl sulfide. Treatment of 3 wi th NOBF4 in CH2Cl2 led to S-R-thiophenium-manganese dicarbohyl nitrosy l cations 4. Photolysis of 4 in acetone gave rise to S-R-thiophenium 5 in high yields. The molecular structures of [{2-exo-P(O)(OMe)(2)-eta( 4)-C4H3S}Mn(CO)(3)] (2(sil,P(O)(OMe)(2))), h-eta(4)-2-{(eta(5)-C6H6)Mn (CO)(3)}SC4H3]Mn(CO)(3) (3(Mn,Ph)), and [P-CH3C6H5-S-2-CH3C4H3] (5(Me, p-tolyl)) have been determined by X-ray studies.