Ring opening and oligomerization of thiirane by hexaosmium carbonyl cluster complexes

Abstract

Metal complexes have played central roles in the initiation and propagation of many important polymerization reactions.1 Studies of the reactions of metal carbonyl cluster complexes with episulfides have shown sulfur transfer and alkene elimination to be the preferred reaction pathway (e.g., eq l).2 Although thiirane, C2H4S, is able to serve as a ligand through coordination of the sulfur atom,3 very little is known about the nature of the ring opening and eventual elimination of alkene in these reactions. The

New evidence on the factors affecting bridging and semibridging character of carbonyl ligands. The structures of Mn2(CO)7(μ‐SCH2CH2S) and its phosphine derivatives Mn2(CO)7‐X(PMe2Ph)X(μ‐SCH2CH2S), × = 1,2

“…In this report we describe the synthesis and structure of the new compound Mn 2 (µ-SCH 2 CH 2 S)(CO) 7 , 1, and the syntheses and structures of a series of its phosphinesubstituted derivatives. All of these compounds contain a bridging ethanedithiolato ligand and a bridging carbonyl ligand that exhibits varying degrees of asymmetric semibridging coordination that appears to be dependent on the nature of the phosphine ligand coordinations.…”

Reactivity of tervalent titanium compounds (.eta.5-C5Me5)2TiR (R = Me, Et): insertion versus .beta.-hydrogen transfer and olefin extrusion. Preparation of the paramagnetic titanium alkoxide, iminoacyl, acyl, vinyl, and azomethide complexes (.eta.5-C5Me5)2TiX and oxidation of these with PbCl2 to the diamagnetic tetravalent derivatives (.eta.5-C5Me5)2Ti(X)Cl

“…Other unsaturated molecules like olefm, MeaCC=N, acetone, and internal acetylenes do not insert readily.% Since 8-hydrogen-containing complexes Cp*,TiFt are liable to lose olefin, and insertion into the Ti-H bond is much faster than insertion into the T i 4 bond, the reactivity of the Cp*,TiR compounds is completely dominated by net 8-hydrogen-transfer reactions. The reactivity of 2 therefore closely resembles that of Cp*2TiH.12J3b For the strongly Lewis acidic, do, group 3 and lanthanide element compounds Cp*,MR, 8-hydrogen elimination, although kinetically within reach, normally competm with other pathways like 8-alkyl eliminations and allylic and vinylic C-H activations. "s6 These reactions are not observed for compounds Cp*,TiR, resulting in relatively simple reactivity patterns.…”

“…A generally applicable method has been worked out to sidestep these problems of characterization. Cp*,TiR compounds can be readily converted into their diamagnetic monochloride analogues Cp*,Ti(R)Cl by oxidation with PbCl, (eq 3).14b The latter compounds are Cp*,TiR + f/zPbC12 -Cp*,Ti(R)Cl+ 7,Pb (3) easily identified by conventional NMR methods. This technique has extensively been applied in this study to demonstrate the presene of ligand R or X in paramagnetic compounds Cp*,TiX and Cp*,TiR obtained from Cp*,TiMe and Cp*,TiEt and reported in this or previous papers.13 In addition to the fact that oxidation to Cp*,Ti(R)Cl is very helpful for identification, the method also is an excellent synthetic route to new mixed hydrocarbyl compounds Cp*,Ti(R)R'.…”

“…tionse3 Some of these compounds are active catalysts for isomerization, hydrogenation, oligomerization, and polymerization of alkene^.^ Of particular interest is the activation of both aromatic and aliphatic C-H bonds by these comple~es.~~~ This proceeds in a concerted fashion, via a highly polar [2, + 2,] transition state, referred to as o-bond metathesisak Concerted mechanisms are characteristic for group 3 and lanthanide compounds, which have high M-C dissociation energies6 and lack low-energy metal electrons. Heteronuclear unsaturated molecules insert into the M-C bond, as is expected for highly polar bonds.…”

Catalytic Transformations of Thiiranes by (Thiirane)W(CO)5Complexes

“…It has also been shown that thiirane can react with metal clusters without the complete elimination of the hydrocarbon fragment, as shown by the formation of complexes containing dithiolato ligands from the reactions of thiirane with Os 6 (CO) 17 (NCMe) and Os 6 (CO) 16 (NCMe) 2 (eq 2) …”