Coordinatively unsaturated ruthenium complexes with a tethered SDmp (Dmp=2,6-dimesitylphenyl) ligand, [(DmpS)Ru(PR(3))][BAr(F) (4)] (3 a: R=Et; 3 b: R=Ph; Ar(F)=3,5-(CF(3))(2)C(6)H(3)), were synthesized by the reactions of [{(p-cymene)RuCl}(2)(mu-Cl)(2)], LiSDmp, phosphines, and NaBAr(F) (4). The Ru--S bonds in 3 a and 3 b were found to serve as the polarized reactive site in reactions with alkyl halides, diazoalkanes, (p-tosyliminoiodo)benzene, phenylacetylene, and H(2). Alkylation of 3 a and 3 b with methyl iodide or ethyl bromide occurred instantaneously to give the thioether complexes [(DmpSR')RuX(PR(3))][BAr(F) (4)] (4 a: R=Et, R'=Me, X=I; 4 b: R=R'=Et, X=Br; 4 c: R=Ph, R'=Me, X=I; 4 d: R=Ph, R'=Et, X=Br). Treatment of 3 a with diazoalkanes N(2)CHR (R=CO(2)Et, SiMe(3)) led to the cycloaddition of carbenes to the Ru--S bond to form [DmpS(CHR)Ru(PEt(3))][BAr(F) (4)] (5 a: R=CO(2)Et; 5 b: R=SiMe(3)), whereas the reaction with (p-tosyliminoiodo)benzene gave rise to [DmpS{NS(O)(C(6)H(4)-4-CH(3))O}Ru(PEt(3))][BAr(F) (4)] (6), which contains a five-membered ruthenacycle of RuSNSO. Addition of phenylacetylene to the Ru--S bond occurred reversibly to produce the vinyl sulfide complexes [DmpS(PhCCH)Ru(PR(3))][BAr(F) (4)] (7 a: R=Et; 7 b: R=Ph). On the other hand, the phenylacetylene at ruthenium slowly isomerized to vinylidene and bridged Ru and S in the products, [DmpS{C(CHPh)}Ru(PR(3))][BAr(F) (4)] (8 a: R=Et; 8 b: R=Ph). Complex 3 a catalyzed the hydrogenation of acetophenone, in which the heterolytic H-H splitting at the Ru-S site is suggested to be involved in the mechanism.

The coordinatiVely unsaturated iron(II) amido complex Cp*Fe{N(SiMe 3 ) 2 } (1) serVes as an efficient precursor for the cleaVage of the N-N bond of diphenylhydrazine. The NdN bond of azobenzene was also found to be actiVated by 1 in the presence of pinacolborane.

Transition-metal complexes with low-coordination numbers are a class of highly reactive substances which are important as key intermediates in catalytic reactions. A number of coordinatively unsaturated transition-metal complexes have been reported, most of which contain bulky alkyl, alkoxy, amide, and phospane ligands.[1] Bulky thiolates are also attractive ligands in this regard. The S-donor ligands are

Transition-metal complexes with low-coordination numbers are a class of highly reactive substances which are important as key intermediates in catalytic reactions. A number of coordinatively unsaturated transition-metal complexes have been reported, most of which contain bulky alkyl, alkoxy, amide, and phospane ligands.[1] Bulky thiolates are also attractive ligands in this regard. The S-donor ligands are