96042-55-6Relevant articles and documents
Experimental and theoretical studies on the mechanism of the C-S bond activation of PdII thiolate/thioether complexes
Kumar, Sushil,Guyon, Fabrice,Knorr, Michael,Labat, Stéphane,Miqueu, Karinne,Golz, Christopher,Strohmann, Carsten
, p. 1303 - 1321 (2017/05/29)
Two equivalents of L (L = 4-methylthio-2-thioxo-1,3-dithiole-5-thiolate or Medmit) react with cis-Pd- (PR3)2Cl2 (R = Ph and Et) to afford Pd(PR3)(η1-L)(η2-L) (R = Et: 1 ; R = Ph: 2) complexes, which have been characterized by X-ray crystallography. These compounds are dynamic in solution due to an exchange of the thiomethyl groups on palladium. Variable-temperature 1H NMR spectroscopy reveals a low coalescence temperature (173 K). Treatment of Pd(diphos)Cl2 (diphos = dppe or dppm) with 2 equiv of L affords thiolato complexes Pd(dppe)(η1-L)2 (3) and Pd(dppm)(η1-L)2 (4). Whereas 3 is rigid in solution with firm η2-coordination of dppe and η1-coordination of the thiolate, two linkage isomers Pd(η2-dppm)(η1-L)2 and Pd(η1-dppm)(η1-L)(η2-L) coexist in a solution of 4. L coordinated on PdII undergoes a S-demethylation reaction leading to dithiolene complexes and MeL. This transformation requires high temperature, and its efficiency depends on the nature of the phosphines as well as the nature of the metal (Pd vs Pt). DFT calculations reveal that the most likely mechanism depends on the lability of phosphines. Starting from M(PR3)2(η1- L)2 (M= Pd and Pt; R = Ph and Et), the favored sequence implies decoordination of one triethyl phosphine (M(PEt3)(η1-L)(η2- L)2 as intermediate) or two triphenylphosphines (Pd(η2-L)2 as intermediate) followed by oxidative addition and reductive elimination (OA/RE) reactions. In the case of PEt3, this OA/RE sequence can also compete with an intramolecular nucleophilic addition (AN), which can be described as an attack of a thiolate sulfur atom on a CH3+ carbocation. An intramolecular SN2 process was found to be the most feasible, starting from M(dppe)(η1-L)2 (M= Pd and Pt), with the nucleophile approaching the thiomethyl group at an angle of 180° with respect to the CCH3-S bond. The influence of the coligand has also been studied experimentally. Structurally characterized disulfide L-L dimer has been isolated upon reaction of 2 equiv of L with MCl2 (M = Pd and Pt).
The synthesis and characterization of platinum monodithiolene complexes containing 1,3-dithiole-2-oxo-4,5-dithiolate (dmid2-) and 1,3-dithiole-2-thione-4,5-dithiolate (dmit2-)
Keefer, Christopher E.,Purrington, Suzanne T.,Bereman, Robert D.,Knight, Brian W.,Bedgood Jr., Danny R.,Boyle, Paul D.
, p. 200 - 208 (2008/10/08)
The platinum monodithiolene complexes (COD)Pt(dmid) (1), (COD)Pt(dmit) (2), (Ph3P)2Pt(dmid) (3) and (Ph3P)2Pt(dmit) (4) (where COD=1,5-cyclooctadiene, dmid=1,3-dithiole-2-oxo-4,5-dithiolate, dmit=1,3-dithiole-2-thione-4,5-dithiolate) have been synthesized and characterized. We report here their 1H NMR, 195Pt NMR, UV-Vis spectra and electrochemistry. The X-ray crystal structures are also reported. 2: orthorhombic, Cmcm, a=10.8535(6), b=16.8503(7), c=7.3622(3) A, Z=4. 3: triclinic, P1, a=11.2051(4), b=11.4409(5), c=15.2212(9) A, α=71.882(4), β=73.125(4), γ= 84.589(6)°, Z=2. 4·CHCl3: triclinic, P1, a=10.2521(5), b=13.9387(14), c=15.6884(18) A, α=67.154(9), β=89.380(15), γ=83.570(13)°, Z=2. The crystal structure of 2 exhibits a molecular stacking pattern which has alternating Pt and S(thione) atoms forming a one-dimensional chain which suggests the presence of a weak axial interaction between the Pt and S(thione). A correlation exists between the 195Pt NMR chemical shifts and the one-electron oxidation potentials of these complexes. In addition, it is shown that the carbonyl of the dmid2- ligand is not susceptible to alkoxide attack when coordinated to platinum.
