Base-induced fragmentation of a macrocyclic thioether at an (arene)ruthenium(II) center. Generation of eta(1)(S)-ethenethiolate and eta(2)(C,S)-thioacetaldehyde

Treatment of the labile (hexamethylbenzene)ruthenium(II) acetone complex [(eta(6)-C(6)Me(6))Ru(OCMe(2))(3)](2+) with 1,4,7-trithiacyclononane (9S3) gives the half-sandwich salt [(eta 6-C(6)Me(6))RU(9S3)] (PF6)(2) (1), which undergoes two successive deprotonations at its methylene carbon atoms in the presence of KOH. The products are chelate vinyl thioether complexes, [(eta(6)-C(6)Me(6))Ru(S(CH=CH2)CH2CH2SCH2CH2S)]PF6 (2) (48% isolated yield) and (eta(6)-C(6)Me(6))Ru(S(CH=CH2)CH2CH2S)(SCH=CH2) (3) (34% isolated yield); the latter also contains the novel eta(1)(S)-ethenethiolate ligand. Treatment of 1 or 2 with more than 3 molar equiv of KO-t-Bu induces deprotonation of one of the C(6)Me(6) methyl groups; addition of the resulting carbanion to the vinyl group of the coordinated thioether of 3 gives Ru(SCH=CH2)(S(CH2CH2CH2-eta(6)-C(6)Me(5))CH2CH2S) (4) (50% is elated yield), which contains a tridentate arene-thioether-thiolate ligand in addition to eta(1)(S)-ethenethiolate. Complexes 2-4 have been characterized by NMR (H-1, C-13) and IR spectroscopy and by single-crystal X-ray structural analysis. Whereas 2 is reconverted into 1 by acid, in the case of 3 and 4 the ethenethiolate groups are protonated to generate cationic complexes containing eta(2)-thioacetaldehyde, i.e., [(eta(6)-C(6)Me(6))Ru(S(CH=CH2CH2CH2S)(eta(2)-SCHCH3)](+.)(8) and [Ru(eta(2)-SCHCH3)(S(CH2-CH2CH2-eta(6)-C(6)Me(5))CH2CH2S)](+) (7), respectively, which exist as diastereomeric mixtures, as shown by H-1 and C-13 NMR spectroscopy. Complex 8 undergoes a slower, second protonation of the vinyl thioether to give, after C-S bond formation, [(eta(6)-C(6)Me(6))RU(S(eta(2)-CHCH3)CH2CH2SCH2CH2S)](2+) (9).