Alkylthio Bridged 44 cve Triangular Platinum Clusters:  Synthesis, Oxidation, Degradation, Ligand Substitution, and Quantum Chemical Calculations

Acetylplatinum(II) complexes <i>trans</i>-[Pt(COMe)Cl(L)<sub>2</sub>] (L = PPh<sub>3</sub>, <b>2a</b>; P(4-FC<sub>6</sub>H<sub>4</sub>)<sub>3</sub>, <b>2b</b>) were found to react with dialkyldisulfides R<sub>2</sub>S<sub>2</sub> (R = Me, Et, Pr, Bu; Pr = <i>n</i>-propyl, Bu = <i>n</i>-butyl), yielding trinuclear 44 cve (cluster valence electrons) platinum clusters [(PtL)<sub>3</sub>(μ-SR)<sub>3</sub>]Cl (<b>4</b>). The analogous reaction of <b>2a</b>−<b>b</b> with Ph<sub>2</sub>S<sub>2</sub> gave SPh bridged dinuclear complexes <i>trans</i>-[{PtCl(L)}<sub>2</sub>(μ-SPh)<sub>2</sub>] (<b>5</b>), whereas the addition of Bn<sub>2</sub>S<sub>2</sub> (Bn = benzyl) to <b>2a</b> ended up in the formation of [{Pt(PPh<sub>3</sub>)}<sub>3</sub>(μ<sub>3</sub>-S)(μ-SBn)<sub>3</sub>]Cl (<b>6</b>). Theoretical studies based on the AIM theory revealed that type <b>4</b> complexes must be regarded as triangular platinum clusters with Pt−Pt bonds whereas complex <b>6</b> 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 <b>4</b> proved to be subject to substitution by stronger donating monodentate phosphine ligands (L‘ = PMePh<sub>2</sub>, PMe<sub>2</sub>Ph, PBu<sub>3</sub>) yielding clusters [(PtL‘)<sub>3</sub>(μ-SR)<sub>3</sub>]Cl (<b>9</b>). In case of the reaction of clusters <b>4</b> and <b>9</b> with PPh<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub> (dppm), a fragmentation reaction occurred, and the complexes [(PtL)<sub>2</sub>(μ-SMe)(μ-dppm)]Cl (<b>12</b>) and [Pt(μ-SMe)<sub>2</sub>(dppm)] (<b>13</b>) were isolated. Furthermore, oxidation reactions of cluster [{Pt(PPh<sub>3</sub>)}<sub>3</sub>(μ-SMe)<sub>3</sub>]Cl (<b>4a</b>) using halogens (Br<sub>2</sub>, I<sub>2</sub>) gave dimeric platinum(II) complexes <i>cis</i>-[{PtX(PPh<sub>3</sub>)}<sub>2</sub>(μ-SMe)<sub>2</sub>] (<b>14</b>, X = Br, I) whereas oxidation reactions using sulfur and selenium afforded chalcogen capped trinuclear 48 ve complexes [{Pt(PPh<sub>3</sub>)}<sub>3</sub>(μ<sub>3</sub>-E)(μ-SMe)<sub>3</sub>] (<b>15</b>, 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 <b>4a</b>, the trinuclear complex <b>6</b>, as well as for the dinuclear complexes <i>trans</i>-[{Pt(AsPh<sub>3</sub>)}<sub>2</sub>(μ-SPh)<sub>2</sub>] (<b>5c</b>), [{Pt(PPh<sub>3</sub>)}<sub>2</sub>(μ-SMe)(μ-dppm)]Cl (<b>12a</b>), and [{{PtBr(PPh<sub>3</sub>)}<sub>2</sub>(μ-SMe)<sub>2</sub>] (<b>14a</b>).