Keywords: Iron / Cluster compounds / S ligands / Hydrogenase / Electrocatalysis / DihydrogenThe reactions of 1,2,4-trithiolane (1), 1,2,5-trithiepane (6), 1,2,5-trithiocane (12) and 1,2,6-trithionane (10) with nonacarbonyldiiron (2) have been investigated. A novel diiron model complex, which can serve as a model complex of the active site of [Fe-only]-hydrogenase, was formed from the reaction with 1. In contrast, the reaction of 6 with 2 afforded the trinuclear iron cluster 7. Interestingly, the diiron compound 11 was obtained with 1,2,6-trithionane (10), which can be attributed to the more flexible dithiolato ligand 10. Furthermore, the reaction with 1,2,5-trithiocane (12) yielded the trinuclear
Oxidation of spirocylcohexyl-1,2,4-trithiolane 1 yielded the 4-S-and 1-S-oxide, 2 and 3, respectively. The complexation reactions of 1-3 with [Pt(η 2 -nb)(PPh 3 ) 2 ] (4; nb = norbornene) have been studied. The formed dithiolato, thioketone, thiolatosulfenato and sulfine complexes 5-8 have been isolated and characterized by 1 H-, 31 P NMR and IR spectroscopy and by mass spectrometry. The mechanism of the reaction is discussed. The reaction proceeds by insertion of the Pt 0 complex fragment into the sulfur-sulfur bond and subsequent ring contraction by extrusion of a thioketone or sulfine. Compari-
The reaction of a series of stable alpha-chlorinated oligosulfanes 2 and 3 with [Pt(eta(2)-C(2)H(4))(Ph(3)P)2] 1 have been investigated. Starting with the alpha-chlorodisulfanes 2 a,b, the platinum dichloride complex 5 and the side-on bonded thioketone platinum complexes 6 a,b were formed. Complex 1 was treated with corresponding trisulfanes 3 a,b to give 5, 6 a,b and the dithiolatocomplexes 7 a,b. We assume that the {Pt(0)(Ph(3)P)2}-complex fragment inserted along the S--S bond to form the unstable intermediate G, which decomposed to form the products described above. We could prove that the sterically crowded 1,2,4-trithiolane 8 was not involved in the reaction pathway by treatment of 1 with 8 under the same conditions; after 24 h, 8 was found to be unreacted. X-ray structure analyses were performed on complexes 6 a, 7 a and 7 b.
Keywords: 1,2,4-Trithiolanes / S ligands / Oxidative addition / Metallacycles / Reactive intermediates Reactions of 1,2,4-trithiolanes with Pt 0 complexes often proceed via an oxidative addition of the Pt 0 complex fragment into the S-S bond and subsequent extrusion of a thioketone molecule by ring contraction. The six-membered intermediate 5a, formed in the course of the reaction of the parent 1,2,4-trithiolane (1a) and Pt 0 complex 4, was detected by
The cover picture shows the insertion of a Pt0 complex fragment into the S–S bond of a 1,2,4‐trithiolane 1‐S‐oxide. Reactions of Pt0 complexes with small sulfur‐containing heterocycles have become more and more popular in order to generate and stabilize reactive sulfur‐containing species. The reaction presented leads to three‐ and four‐membered platinacycles by ring contraction with expulsion of the reactive thiocarbonyl derivatives. The postulated mechanism for the fragmentation of 1,2,4‐trithiolane 1‐S‐oxide, as well as the molecular structures, give a reasonable explanation for the observed selectivity. Details are discussed in the article by W. Weigand, G. Mloston et al. on p. 5627 ff. We thank Dr. Jaroslaw Romanski for decorating our Christmas tree (background) for this year and designing the cover picture.
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