Facile allylic C-H bond activation on the bridging disulfide ligand in the Ru(III) dinuclear complex having a conjugated RuSSRu core

C-H cleavage and double alkyl additions to the disulfido ligand in dicyanido-bridged Ru2S2 complexes

Novel dicyanido-bridged dicationic RuIIISSRuIII complexes [{Ru(P(OCH3)3)2}2(mu-S2)(mu-X)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (4, X=Cl, Br) were synthesized by the abstraction of the two terminal halide ions of [{RuX(P(OCH3)3)2}2(mu-S2)(mu-X)2] (1, X=Cl, Br) followed by treatment with m-xylylenedicyanide. 4 reacted with 2,3-dimethylbutadiene to give the C4S2 ring-bridged complex [{Ru(P(OCH3)3)2}2{mu-SCH2C(CH3)=C(CH3)CH2S}(mu-X)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (6, X=Cl, Br). In addition, 4 reacted with 1-alkenes in CH3OH to give alkenyl disulfide complexes [{Ru(P(OCH3)3)2}2{mu-SS(CH2C=CHR)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3) (7: R=CH2CH3, 9: R=CH2CH2CH3) and alkenyl methyl disulfide complexes [{Ru(P(OCH3)3)2}2{mu-S(CH3)S(CH2C=HR)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (8: R=CH2CH3, 10: R=CH2CH2CH3) via the activation of an allylic C-H bond followed by the elimination of H+ or condensation with CH3OH. Additionally, the reaction of 4 with 3-penten-1-ol gave [{Ru(P(OCH3)3)2}2{mu-SS(CH2C=CHCH2OH)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3) (11) via the elimination of H+ and [{Ru(P(OCH3)3)2}2(mu-SCH2CH=CHCH2S)(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (12) via the intramolecular elimination of a H2O molecule. 12 was exclusively obtained from the reaction of 4 with 4-bromo-1-butene.

Elimination of HX (X = Cl, Br) from haloalkenes on the Ru2Q2 (Q = S, Se) core complex

Treatment of [[Ru(P(OCH3)3)2(CH3CN)3]2(mu-Q2)](CF3SO3)4 (1, Q = S; 2, Q = Se) with haloalkenes resulted in the formation of complexes carrying unsaturated C3Q2 five-membered or C4Q2 six-membered rings via elimination of HX (X = Cl, Br). The reactions of 1 and 2 with allyl bromide gave the corresponding addition products, [[Ru(P(OCH3)3)2(CH3CN)3]2(mu-QCH=CHCH2Q)](CF3SO3)4 (3, Q = S; 4, Q = Se), via elimination of HBr. The elimination process seems to be thermodynamically controlled and takes place at the final stage of the reaction. The steric effect of the halogen atoms seems more operative than the electronic one.

Dehydration reaction of hydroxyl substituted alkenes and alkynes on the Ru(2)S(2) complex

A variety of inter- and intramolecular dehydration was found in the reactions of [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)(mu-S(2))](CF(3)SO(3))(4) (1) with hydroxyl substituted alkenes and alkynes. Treatment of 1 with allyl alcohol gave a C(3)S(2) five-membered ring complex, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)CH(2)CH(OCH(2)CH=CH(2))S]](CF(3)SO(3))(4) (2), via C-S bond formation after C-H bond activation and intermolecular dehydration. On the other hand, intramolecular dehydration was observed in the reaction of 1 with 3-buten-1-ol giving a C(4)S(2) six-membered ring complex, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2) [mu-SCH(2)CH=CHCH(2)S]](CF(3)SO(3))(4) (3). Complex 1 reacts with 2-propyn-1-ol or 2-butyn-1-ol to give homocoupling products, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCR=CHCH(OCH(2)C triple bond CR)S]](CF(3)SO(3))(4) (4: R = H, 5: R = CH(3)), via intermolecular dehydration. In the reaction with 2-propyn-1-ol, the intermediate complex having a hydroxyl group, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH=CHCH(OH)S]](CF(3)SO(3))(4) (6), was isolated, which further reacted with 2-propyn-1-ol and 2-butyn-1-ol to give 4 and a cross-coupling product, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH=CHCH(OCH(2)C triple bond CCH(3))S]](CF(3)SO(3))(4) (7), respectively. The reaction of 1 with diols, (HO)CHRC triple bond CCHR(OH), gave furyl complexes, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SSC=CROCR=CH]](CF(3)SO(3))(3) (8: R = H, 9: R = CH(3)) via intramolecular elimination of a H(2)O molecule and a H(+). Even though (HO)(H(3)C)(2)CC triple bond CC(CH(3))(2)(OH) does not have any propargylic C-H bond, it also reacts with 1 to give [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)C(=CH(2))C(=C=C(CH(3))(2))]S](CF(3)SO(3))(4) (10). In addition, the reaction of 1 with (CH(3)O)(H(3)C)(2)CC triple bond CC(CH(3))(2)(OCH(3)) gives [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(2)][mu-S=C(C(CH(3))(2)OCH(3))C=CC(CH(3))CH(2)S][Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)]](CF(3)SO(3))(4) (11), in which one molecule of CH(3)OH is eliminated, and the S-S bond is cleaved.

Reactions of dithiolate ligands in mononuclear complexes of rhenium(V)

The thermal reactions of the Re(V) dithiolate complex Cp'ReCl2(SCH2CH2S), 1 (where Cp' = EtMe4C5), and related derivatives have been studied. When 1 is heated in toluene in a sealed evacuated tube at 100 degrees C, a dehydrogenation reaction occurs to form a new rhenium complex with a dithiolene ligand, Cp'ReCl2(SCHCHS), 6, in ca. 40% yield. The structure of 6 has been confirmed by an X-ray diffraction study. Under the thermal conditions studied, 1 also undergoes an olefin extrusion reaction. Free ethene is detected in the NMR spectrum of the products, and insoluble rhenium products are also formed. When 1 is reacted with excess ethene under mild conditions, a new organic product, 1,4-dithiane, is formed. Complex 1 is also found to react with oxidants, such as O2 and S8, under mild conditions to form the dehydrogenation product 6. Kinetic studies of the thermal reaction of 1 and related derivatives have been completed, and possible mechanisms for the thermally induced dehydrogenation reaction are discussed.