Reactions of elemental sulfur with tetrakis(triphenylphosphine)platinum(0). Formation of a complex containing very nucleophilic bridging sulfido ligands

Abstract

The reactions of Pt(PPh3)4 with elemental sulfur in ratios S/Pt = 3, 4, 5, and 6 give a mixture of compounds identified as [PtS(PPh3)2]2 and PtS4(PPh3)2; PtS2(PPh3)2 is not detected. The dimeric complex also forms on reaction of PtS4(PPh3)2 with 3 mol of Pt(C2H4)(PPh3)2. It is alkylated at one bridging sulfido ligand by CH2Cl2 and CHCl3 to give cations [Pt2(μ-S)-(μ-SR)(PPh3)4]+, R = CH2Cl and CHCl2, respectively, which are characterized as their hexafluorophosphate salts. The cations give extreme AA′BB′X 31Pmr spectra since their cis-phosphorus atoms (A,B) have very similar chemical shifts but different coupling constants to 195Pt(X); spectral features are broadened by thiolate inversion processes. Reactions of bridging sulfido ligands with other electrophiles are discussed.

Extending The Reaction Landscape of the {Pt(μ‐S)2Pt} Core: From Metal Centers to Non‐Metallic Electrophiles

“…Thus, the first step of the reaction involves monoalkylation of the corresponding {Pt(µ-S) 2 Pt} core to yield spectroscopically identifiable intermediates with the formula [L 2 {Pt(µ-S)(µ-SCH 2 Cl)Pt}L 2 ] ϩ , [9,68,69] whose energy is only slightly higher than that of the reactants. Overall, the reactivity of [L 2 Pt(µ-S) 2 PtL 2 ] towards CH 2 Cl 2 provides evidence for the complex sequence of reactions triggered by the nucleophilicity of the sulfur atoms in the {Pt 2 S 2 } core and shows the ability of the terminal phosphane ligands to tune such reactions.…”

Hydrogen Bonding in Crystalline Alcohol Solvates of the Platinum(II) Sulfido Complex [Pt2(μ‐S)2(PPh3)4]

“…Analysis of the product by 1 H NMR spectroscopy in CDCl 3 solution showed the presence of ethanol; integration relative to the PPh 3 resonances suggested the presence of two ethanol molecules per mol of [Pt 2 (µ-S) 2 -(PPh 3 ) 4 ]. Complexes with {Pt 2 S 2 } cores are known to react with chlorinated hydrocarbon solvents such as CH 2 Cl 2 and CHCl 3 , [9][10][11] but this does not invalidate the determination of the presence and amount of ethanol solvent. Elemental microanalytical data for 2a were also supportive of the assignment, thought it must be noted that the theoretical C and H percentages for [Pt 2 (µ-S) 2 4 ]·2EtOH (C 57.2, H 4.6) are rather similar, and within the error of the determination.…”

Alkylation of [Pt2(μ-S)2(PPh3)4] with boronic acid derivatives

“…[3][4][5][6][7][8][9][10][11] Alkylation reactions of 1 with mild electrophiles was realised in the early preliminary studies. [12][13][14][15] Recently, the rudimentary reactivity of 1 with simple mild alkylating agents 13 has been extended to functionalized alkylating agents (electrophiles). 16,17 The alkylation of 1 provides a facile route for the generation of functionalized thiolate ligands .…”