Arenethiolate Ligands Research Articles

Synthesis of Molybdenum and Tungsten Alkylidene Complexes That Contain Sterically Demanding Arenethiolate Ligands.

Imido alkylidene complexes of Mo and W and oxo alkylidene complexes of W that contain thiophenoxide ligands of the type S-2,3,5,6-Ph4C6H (STPP) and S-2,6-(mesityl)2C6H3 (SHMT = S-hexamethylterphenyl) have been prepared in order to compare their metathesis activity with that of the analogous phenoxide complexes. All thiolate complexes were significantly slower (up to ∼10× slower) for the metathesis homocoupling of 1-octene or polymerization of 2,3-dicarbomethoxynorbornene, and none of them was Z-selective. The slower rates could be attributed to the greater σ-donating ability of a thiophenoxide versus the analogous phenoxide and consequently a higher electron density at the metal in the thiophenoxide complexes.

Surface chemistry of arenethiolate-capped PbS quantum dots and application as colloidally stable photovoltaic ink

Suitable post-synthesis surface modification of lead-chalcogenide quantum dots (QDs) is crucial to enable their integration in photovoltaic devices. We have developed a solution-phase ligand exchange strategy that exploits arenethiolate anions to replace the pristine oleate ligands on PbS QDs, while preserving the long-term colloidal stability of QDs and allowing their solution-based processability into photoconductive thin-films. Complete QD surface modification is demonstrated by IR spectroscopy analysis, whereas UV–Vis–NIR Absorption Spectroscopy provides quantitative evaluation of stoichiometry and thermodynamic stability of the resulting system. Arenethiolate ligands permit to reduce the inter-particle distance in PbS QD solids, leading to a drastic improvement of the photoinduced charge transport properties. Therefore, smooth dense-packed thin-films of arenethiolate-capped PbS QDs obtained via a single solution-processing step are integrated in heterojunction solar cells: such devices generate remarkable photocurrent densities (14mAcm−2) and overall efficiencies (1.85%), which are outstanding for a single PbS QD layer. Solution-phase surface modification of QDs thus represents an effective intermediate step towards low-cost processing for all-inorganic and hybrid organic/inorganic QD-based photovoltaics.

Electrochemical properties of 2,2':6', 2 -terpyridine complexes of platinum(II) with arenethiolate ligands. Alkylation of reduced forms of the complexes

Three mixed-ligand terpyridine-thiolate PtII complexes containing 2,2":6",2″-terpyridine (tpy) and para-substituted thiophenolate ions, [(tpy)Pt(SC6H4-4-X)]BF4 (X = NMe2, H, NO2) were synthesized. The complexes were isolated as chlorides or tetrafluoroborates and characterized by electrochemistry, visible electronic spectroscopy and 1H NMR spectroscopy, and elemental analysis. Remarkable influence of the electron-donating/withdrawing properties of the substituent in the thiolate ligand on the physicochemical properties of the complexes, in particular, on the electrochemical reduction potentials, was found. The reduced forms of the complexes undergo electrochemically initiated alkylation with alkyl halides, resulting in the formation of Pt alkyl compounds.

Electron Hopping through Films of Arenethiolate Monolayer-Protected Gold Clusters

Electron hopping in films of arenethiolate (benzylthiolate, phenylethylthiolate, phenylbutanethiolate, and cresolthiolate) monolayer-protected cluster molecules (MPCs) is investigated through measurements of solid-state electronic conductivity. Electron donor−acceptor hopping rates between the Au cores of arenethiolate MPCs exceed those of previously studied solid-state alkanethiolate MPC films, but the electronic coupling term, β = 0.8 Å-1, is nearly the same. Rate constants range from 108 to 1011 s-1 across the series of arenethiolate MPCs; for the case of cresolthiolate, the rate corresponds to a single molecule resistance of ∼107 Ω/cresolthiolate ligand. The 4−8 kJ/mol activation-barrier energies for electron hopping are generally in line with the Marcus theory prediction. The low barrier energies and large rate constants arise from a combination of the low dielectric medium environment of the reactants (the MPC cores) and the partly aromatic tunneling bridges. The sharp increase in film conductivity upon substituting arenethiolate ligands for >50% of the hexanethiolates on a hexanethiolate-protected MPC suggests a percolation effect.

Synthetic, Structural, and Redox Studies of Arene Alkyl Complexes of Tantalum(III) Supported by Aryloxide and Arenethiolate Ligands

A series of η6-hexamethylbenzene alkyl and aryl complexes of tantalum(III) supported by aryloxide and arenethiolate ligands have been prepared, characterized, and compared to their halide analogues. Thus, (η6-C6Me6)Ta(OAr)2Cl (1, Ar = 2,6-C6H3iPr2) reacts with MeMgBr at low temperature to afford (η6-C6Me6)Ta(OAr)2Me (3). Low-temperature alkylation of (η6-C6Me6)Ta(OAr)Cl2 (2) with 2 equiv of RMgBr forms (η6-C6Me6)Ta(OAr)R2 (4, R = Me; 5, R = Et) and with 2 equiv of RLi affords (η6-C6Me6)Ta(OAr)R2 (6, R = CH2SiMe3; 7, R = Ph). Complexes 3−7 are more stable than their halide precursors; no products arising from α- or β-H elimination processes were identified upon thermolysis. In addition to NMR studies of these compounds, cyclic voltammetry experiments show two oxidation processes; the Ta(III) ⇄ Ta(IV) couple is quasi-reversible, and the Ta(IV) → Ta(V) process is irreversible. Molecules of 5 exhibit a folded arene ligand with π-electron localization (diene−diyl structure) and normal ethyl ligands (no evidence for agostic interactions). Under the appropriate conditions, (η6-C6Me6)Ta(OAr)Cl2 (2) can be monoalkylated using 1 equiv of LiCH2SiMe3 or LiPh to afford (η6-C6Me6)Ta(OAr)(CH2SiMe3)Cl (8) and (η6-C6Me6)Ta(OAr)(Ph)Cl (9). However, attempts to monoalkylate (η6-C6Me6)Ta(OAr)Cl2 with 1 equiv of either MeMgBr or EtMgBr provide the “double-exchange” products (η6-C6Me6)Ta(OAr)(Me)Br (10) and (η6-C6Me6)Ta(OAr)(Et)Br (11), respectively. The metathesis product (η6-C6Me6)Ta(OAr)(Et)Cl (12) is isolated in good yield upon attempts to alkylate (η6-C6Me6)Ta(OAr)(CH2SiMe3)Cl (8) with ZnEt2. However, (η6-C6Me6)Ta(OAr)(CH2SiMe3)Cl (8) reacts with PhLi to afford (η6-C6Me6)Ta(OAr)(CH2SiMe3)Ph (13). The halide alkyl complexes (η6-C6Me6)Ta(OAr)(Et)Br (11) and (η6-C6Me6)Ta(OAr)(CH2SiMe3)Cl (8) react with LiBEt3H to provide the hydrido complexes (η6-C6Me6)Ta(OAr)(Et)H (14) and (η6-C6Me6)Ta(OAr)(CH2SiMe3)H (15), respectively. The arenethiolate complexes (η6-C6Me6)Ta(OAr)(SAr‘)Cl (16) (Ar‘ = 2,4,6-C6H2iPr3) and (η6-C6Me6)Ta(OAr)(S(mes))Cl (17) (mes = 2,4,6-C6H2Me3) are formed upon reacting (η6-C6Me6)Ta(OAr)Cl2 (2) with the appropriate lithium arenethiolate reagent, and the characterization of these species is discussed.

Palladium arenethiolates with intramolecularly coordinating nitrogen lewis bases

AbstractThe reaction of [PdCl2(MeCN)2] with one or two equivalents of Me3SiSC6H4NMe2‐2 in toluene affords the mono(arenethiolate) complex [PdCl(SC6H4NMe2‐2)] (1) or the bis(arenethiolate) complex [Pd(SC6H4NMe2‐2)2] (2), respectively, in high yields. [PdCl(SC6H4NMe2‐2)] (1) exists as a tetramer in the solid state (X‐ray) while [Pd(SC6H4NMe2‐2)2] (2) is a monomer both in the solid state and in solution (cryoscopy, NMR). The X‐ray structure determination of tetrameric 1 shows arenethiolate ligands bridging between PdCl units to form a unique eight‐membered U‐shaped Pd4S4 ring. Crystals of 1 are tetragonal, space group magnified image, with a = b = 12.0495(10) Å, c = 16.672(1) Å, V= 2420.6(3) Å3, Z = 2, and final R = 0.029, wR = 0.034 and S = 1.42 for 1174 reflections with I > 2.5 σ(I) and 111 variables. The X‐ray structure determination of 2 shows it to be monomeric in the solid state. The palladium has a square‐planar geometry that results from coordination by two S,N‐chelating arenethiolate ligands with a trans S and trans N arrangement of the donor atoms. Crystals of 2 are triclinic, space group magnified image, with a = 8.9923(5) Å, b = 9.2472(5) Å, c = 11.5933(6) Å, V = 825.93(9) Å3, Z = 2, and final R = 0.025, wR = 0.047 and S = 0.53 for 3603 reflections with I > 2.5 σ(I) and 226 variables.

ChemInform Abstract: First Examples of Six‐Coordinate Homoleptic Complexes with Monodentate Arenethiolate Ligands. Synthesis and Structural Characterization of ( Ph4P)2(Nb(SPh)6), Na(THF)3Nb(SPh‐pMe)6, ((15‐crown‐5)Na)(Ta(SPh)6), and Nb2(μ2‐SPh)4(SPh)2Cl2(C2H5CN)2.

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First examples of six-coordinate niobium and tantalum homoleptic complexes with monodentate arenethiolate ligands. Synthesis and structural characterization of [Ph4P]2[Nb(SPh)6], Na(THF)3Nb(SPh-pMe)6. [(15-crown-5)Na][Ta(SPh)6], and Nb2(.mu.2-SPh)4(SPh)4(SPh)2Cl2(C2H5CN)2

First examples of six-coordinate niobium and tantalum homoleptic complexes with monodentate arenethiolate ligands. Synthesis and structural characterization of [Ph4P]2[Nb(SPh)6], Na(THF)3Nb(SPh-pMe)6. [(15-crown-5)Na][Ta(SPh)6], and Nb2(.mu.2-SPh)4(SPh)4(SPh)2Cl2(C2H5CN)2

ChemInform Abstract: Preparation and Characterization of Molybdenum(IV)‐Alkyne Complexes Containing Bulky Aryloxide or Arenethiolate Ligands.

AbstractStarting with the tetrachloroalkyne complexes (III) or the tetrakis(arenethiolate) complexes (VII), the title complexes (I) and (II) are prepared as shown in the scheme.

Preparation and characterization of molybdenum(IV)-alkyne complexes containing bulky aryloxide or arenethiolate ligands

Preparation et structure cristalline des complexes Mo(alcyne)(DIPP) 2 Cl 2 , Mo(alcyne)(DIPP) 3 Cl et Mo(alcyne)(DIPP) 4 (DIPP= − O-C 6 H 3 -i-Pr 2 ) et Mo(alcyne)(TIPT) 4 (TIPT= − S-C 6 H 2 -i-Pr 3 ). Reactions electrochimiques