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Albrecht C, Schwieger S, Bruhn C, Wagner C, Kluge R, Schmidt H, Steinborn D: Alkylthio bridged 44 cve triangular platinum clusters: synthesis, oxidation, degradation, ligand substitution, and quantum chemical calculations. J Am Chem Soc. 2007 Apr 18;129(15):4551-66. Epub 2007 Mar 23.
Acetylplatinum (II) complexes trans-[Pt (COMe) Cl (L) 2] (L = PPh3, 2a; P (4-FC6H4) 3, 2b) were found to react with dialkyldisulfides R2S2 (R = Me, Et, Pr, Bu; Pr = n-propyl, Bu = n-butyl), yielding trinuclear 44 cve (cluster valence electrons) platinum clusters [(PtL) 3 (mu-SR) 3] Cl (4). The analogous reaction of 2a-b with Ph2S2 gave SPh bridged dinuclear complexes trans-[{PtCl (L)}2 (mu-SPh) 2] (5), whereas the addition of Bn2S2 (Bn = benzyl) to 2a ended up in the formation of [{Pt (PPh3)}3 (mu3-S)(mu-SBn) 3] Cl (6). Theoretical studies based on the AIM theory revealed that type 4 complexes must be regarded as triangular platinum clusters with Pt-Pt bonds whereas complex 6 must be treated as a sulfur capped 48 ve (valence electrons) trinuclear platinum (II) complex without Pt-Pt bonding interactions. Phosphine ligands with a lower donor capability in clusters 4 proved to be subject to substitution by stronger donating monodentate phosphine ligands (L' = PMePh2, PMe2Ph, PBu3) yielding clusters [(PtL') 3 (mu-SR) 3] Cl (9). In case of the reaction of clusters 4 and 9 with PPh2CH2PPh2 (dppm), a fragmentation reaction occurred, and the complexes [(PtL) 2 (mu-SMe)(mu-dppm)] Cl (12) and [Pt (mu-SMe) 2 (dppm)] (13) were isolated. Furthermore, oxidation reactions of cluster [{Pt (PPh3)}3 (mu-SMe) 3] Cl (4a) using halogens (Br2, I2) gave dimeric platinum (II) complexes cis-[{PtX (PPh3)}2 (mu-SMe) 2] (14, X = Br, I) whereas oxidation reactions using sulfur and selenium afforded chalcogen capped trinuclear 48 ve complexes [{Pt (PPh3)}3 (mu3-E)(mu-SMe) 3] (15, E = S, Se). All compounds were fully characterized by means of NMR and IR spectroscopy, microanalyses, and ESI mass spectrometry. Furthermore, X-ray diffraction analyses were performed for the triangular cluster 4a, the trinuclear complex 6, as well as for the dinuclear complexes trans-[{Pt (AsPh3)}2 (mu-SPh) 2] (5c), [{Pt (PPh3)}2 (mu-SMe)(mu-dppm)] Cl (12a), and [{{PtBr (PPh3)}2 (mu-SMe) 2] (14a). |
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