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Abstract: Exploring efficient Pt‐free hydrogen evolution reaction (HER) electrocatalyst with low cost and earth‐abundance is a critical challenge. Herein, highly active and stable Mo/α‐MoC1−x catalyst is synthesized via a simple pyrolysis of a MoO3/ethylenediamine hybrid precursor in reductive atmosphere. The as‐prepared Mo/α‐MoC1−x shows excellent HER activity with a low onset potential of −75 mV (vs reversible hydrogen electrode), a small Tafel slope of 81.7 mV dec−1, as well as good stability in acid electrolytes owing to the synergistic effect of Mo and α‐MoC1−x. This novel structure is a candidate for other energy related fields and this simple synthesis method can be further applied for the synthesis of other hybrid catalysts. [ABSTRACT FROM AUTHOR]

Treatment of trans-[MoCl4(MeCN)2] with L (L = Me2S, Me2Se, THT, ½MeSCH2CH2SMe) in CH2Cl2 solution, or reaction of MoCl5 with excess L′ (L′ = nBu2S, nBu2Se, ½MeSCH2CH2SMe, ½iPrSCH2CH2SiPr, ½MeSCH2CH2CH2SMe, ½MeSeCH2CH2CH2SeMe) in MeCN, produces the Mo(iv) complexes, [MoCl4(L)2] and [MoCl4(L′)2], respectively, in good yield. The new complexes have been characterised by IR and UV-vis spectroscopy, elemental analysis and magnetic measurements, whilst crystal structure analyses of trans-[MoCl4(Me2S)2], cis-[MoCl4{RS(CH2)2SR}] (R = Me, iPr) and cis-[MoCl4{MeS(CH2)3SMe}] confirmed their identities and distorted octahedral geometries. The potential of [MoCl4(nBu2E)2] (E = S, Se) as the first examples of molybdenum halide derived single source CVD precursors for the growth of MoE2 thin films was first probed by TGA, which showed multi-step decomposition processes, with the masses of the final residues consistent with MoSe2 (E = Se) and MoCl4 (E = S), respectively. Low pressure CVD experiments conducted at 750 °C (E = S) and 525 °C (E = Se) gave silvery and golden yellow films, respectively. Grazing incidence and in plane XRD data confirmed these to be 2H-MoE2, whilst the texture of the MoSe2 was investigated using pole figure measurements. SEM and EDX data, optical and Raman data on the films are also reported. [ABSTRACT FROM AUTHOR]

A novel liquid phase synthesis of MoS 2 thin films has been achieved. Solubility of Molybdenum(V) chloride in appropriate solvent was optimized while having good coating properties essential for thin film formation. Chemical conversion of the deposited Mo-precursor films on silicon/silicon dioxide substrate to MoS 2 were obtained by annealing in presence of sulfur. This novel method allows facile upscaling process to large substrates with uniform film thickness down to 4 nm, which are of high interest for future low-cost fabrication of electronic devices. UV–Vis, Raman spectroscopy, and X-ray photoelectron spectroscopy measurements confirm the formation of MoS 2 films with a stoichiometric chemical composition of Mo/S ~ 0.47. Furthermore, X-ray diffraction and Transmission electron microscopy measurements revealed formation of polycrystalline films with random grain orientation attributed to the amorphous SiO 2 surface of the substrate. Improved crystallinity of deposited films was achieved by increasing the process temperature. Annealing at temperatures above 750 °C increased the uniformity of multilayer films, together with the increase of MoS 2 grain size to 100 nm. This simple wet-chemical synthesis approach allows upscaling, controllable film thickness and is suitable for preparation of other transition metal dichalcogenides thin films for applications in the future electronics. [ABSTRACT FROM AUTHOR]

The crystallization of a high-purity hexamolybdenum cluster chloride, Cs2[Mo6Cl14], was investigated with the aim of improving its intrinsic properties, including optical properties. In particular, we used the hydrophilicities of alcoholic solvents to purify Cs2[Mo6Cl14] by dehydration. The precursor, trigonal Cs2[Mo6Cl14] with water impurities, or monoclinic Cs2[Mo6Cl14]·H2O, was dispersed in methanol (MeOH), ethanol (EtOH), or 1-propanol (1-PrOH) to induce recrystallization during stirring. As a result, regardless of the precursor, Cs2[Mo6Cl14] crystallized from EtOH and 1-PrOH, while Cs2[Mo6Cl14]·H2O crystallized from MeOH, which indicates that EtOH and 1-PrOH behave as dehydrating agents during recrystallization. Subsequent characterization by X-ray diffraction, thermal desorption, and infrared spectroscopic techniques confirmed that the Cs2[Mo6Cl14] crystallized from EtOH or 1-PrOH, particularly 1-PrOH, is of high purity (fewer inserted water molecules) and high crystallinity. Improved luminescence efficiency following purification was evidenced by time-resolved photoluminescence measurements; the Cs2[Mo6Cl14] purified by dehydration on recrystallization clearly exhibited an increased luminescence lifetime. [ABSTRACT FROM AUTHOR]

This work describes a novel single precursor vapor phase infiltration (VPI) process to dope polyaniline (PANI). The infiltration is performed with the metal containing atomic layer deposition precursors MoCl5 or SnCl4. The conductivities are assessed with four-point probe measurements and show significant enhancements by up to 6 orders of magnitude, confirming the efficiency of the VPI process. Furthermore, it is found that the conductivities of PANI/MoCl5 and PANI/SnCl4 outperform the conductivity of HCl-doped PANI if exposed to elevated temperatures (150 °C) in vacuum. The chemical changes resulting from the infiltration of PANI are characterized applying FTIR and Raman spectroscopy. Scanning electron microscopy images show that the morphologies of the samples do not alter after the infiltration process. [ABSTRACT FROM AUTHOR]

The reactions between MoCl5 and 1-2 equiv. of a selection of sulfoxides at room temperature in dichloromethane as solvent were studied. The 1:1 molar reaction between MoCl5 and dimethyl sulfoxide (DMSO) afforded the C-S coupling product [Me2SCH2SMe][MoOCl4] ( 1), which was isolated in 46 % yield and characterized by analytical and spectroscopic methods and by X-ray diffraction. MoOCl3, SMe2 and HCl were identified as side products. The reactions between MoCl5 and tetrahydrothiophene 1-oxide, nBu2SO, MePhSO or (PhCH2)2SO yielded the corresponding sulfides and, in the cases of (PhCH2)2SO and MePhSO, also C-S activation compounds. According to DFT calculations, the unusual formation of 1 is the consequence of thermodynamically feasible Cl/O interchange between MoCl5 and DMSO, this being a prerequisite for successive C-H bond activation. [ABSTRACT FROM AUTHOR]

The reaction of [MoO 2 (acac) 2 ] with ( E )-2-((2-(benzo[ d ]thiazol-2-yl)hydrazono)methyl)-6-methoxyphenol ( H 2 L ), in acetonitrile and ethanol resulted in the formation of {[MoO 2 (HL)(H 2 O)] 2 [Mo 6 O 19 ]·2MeCN} ( 1 ) (mononuclear cationic complex with hexamolybdate anion) and [MoO 2 L(EtOH)] ( 2 ) (neutral mononuclear complex), depending on the reaction conditions. In these compounds, the ligand is coordinated to the cis -MO 2 2+ core via phenolic-oxygen, thiazole and azomethine nitrogen atoms, while the remaining sixth coordination site is occupied by the oxygen atom from the solvent molecule. Crystal and molecular structures of the compounds 1 and 2 were determined by the single crystal X-ray diffraction method. All of the investigated compounds were further characterized by elemental analysis, FT-IR and NMR spectroscopy. The molybdenum(VI) species were used as catalyst for olefin oxidation in the presence of tert -butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal Mo loading, the presence of the {[MoO 2 (HL)(H 2 O)] 2 [Mo 6 O 19 ]·2MeCN} ( 1 ) resulted in higher oxidation conversion than [MoO 2 L(EtOH)] ( 2 ). It seems 1 contains two potentially active parts, the [MoO 2 (HL)H 2 O] + cation and the Mo 6 O 19 −2 anion. [ABSTRACT FROM AUTHOR]

Distinct batches of orange (1a–e) and green crystals (2a–e) were isolated from the reactions of MoCl5 with tetrahydropyran (thp), respectively at room temperature (in CH2Cl2) and at ca. 80 °C (in ClCH2CH2Cl). Crystals 2a–e are isomorphous to 1a–e and the IR spectra are almost superimposable. 1a–e were identified by X-ray studies as cis-MoCl4(thp)2, in agreement with previous findings. Careful refinement of the X-ray data of 2a–e by modeling one position as disordered between chlorine (minor component) and oxygen (major component) led to the conclusion that 2a–e consisted of a mixture of cis-MoCl4(thp)2 and mer-MoOCl3(thp)2, the latter being largely prevalent. [ABSTRACT FROM AUTHOR]

The reactivity of MoCl5 with α-amino acids was investigated for the first time by choosing CH2Cl2 as the reaction medium. The interaction of MoCl5 with l-proline proceeded with Cl/O interchange and led to the formation of [NH2(CH2)3CHC(O)Cl][MoOCl4], 1, in 63% yield. The reactions of MoCl5 with l-phenylalanine, sarcosine, N,N-dimethylglycine and N,N-dimethyl-l-phenylalanine afforded the α-amino-acylchloride complexes MoOCl3[O=C(Cl)CH(R)N(R′)(R′′)] (R = CH2Ph, R′ = R′′ = H, 2a; R = R′ = H, R′′ = Me, 2b; R = H, R′ = R′′ = Me, 2c; R = CH2Ph, R′ = R′′ = Me, 2d), in ca. 70% yields. According to DFT studies, 2a,d are mononuclear Mo(v) octahedral complexes bearing a N,O-coordinated α-amino-acylchloride ligand. The presumed species formed during the first stages of the MoCl5/l-phenylalanine interaction were DFT-elucidated, thus the calculated Gibbs free energy profile for the multi-step reaction of MoCl5 with l-phenylalanine was traced. [NH3CH(CH2Ph)C(O)Cl][MoOCl4], 3, acting as an intermediate in the course of the formation of 2a, was isolated by combination of [NH3CH(CH2Ph)C(O)Cl][Cl] with MoOCl3. [ABSTRACT FROM AUTHOR]

We have studied the thermal stability of a MoClCH composite in vacuum (10 Pa) at temperatures from 70 to 1150°C. Using chemical and physicochemical analysis data (gas liquid chromatography, MALDI TOF mass spectrometry, and X-ray diffraction), we have identified the nature of the decomposition products of the composite. The solid residue after the decomposition has been shown to consist predominantly of hexagonal molybdenum carbide MoC, with finely dispersed carbon as an impurity phase. Volatile components have been identified as a mixture of alkyl-substituted anthracenes (phenanthrenes) and polycyclic hydrocarbons with saturated and aromatic rings. These results were used to gain insight into the structure of the hydrocarbon matrix of the composite. [ABSTRACT FROM AUTHOR]

The unique oxidizingpower of molybdenum pentachloride providesan easy to perform, versatile, and high yielding method to constructcarbazoles and the corresponding dibenzo analogues of thiophene, furan,and selenophene. The coupling reaction tolerates a variety of functionalgroups. The synthesis is highly modular. By this approach a precursorfor the naturally occurring carbazole koenigicine was prepared. [ABSTRACT FROM AUTHOR]

Abstract: Mo(VI) and Mo(V) salts both react selectively with Hantzsch esters to produce substitute pyridines in good-to-excellent yield (75–99%). The remarkable reactivity and selectivity of MoOCl4 under reflux of acetonitrile and MoCl5 in dichloromethane at room temperature encouraged us to propose that molybdenum-containing enzymes (such as xanthine or aldehyde oxidase) also participate to some degree in the metabolism of 1,4-dihydropyridine drugs in the liver analogous to NADH in the respiratory chain. [Copyright &y& Elsevier]

The structure of β-molybdenum dichloride is compared with that of TcCl2 using EXAFS spectroscopy. For TcCl2, the Tc atom is surrounded by Tc atoms at 2.13(2), 3.45(3), 3.79(4), and 4.02(4) Å. For β-MoCl2, the Mo is surrounded by Mo atoms at 2.21(2), 2.91(3), and 3.83(4) Å. The latter distances are consistent with the presence of an [Mo4Cl12] unit in the solid state, one constituted by two triply Mo-Mo-bonded [Mo2Cl8] units. First-principles calculations show that β-MoCl2 with the TcCl2 "structure type" is less stable than α-MoCl2 (Mo6Cl12) or [Mo4Cl12] edge-sharing clusters. [ABSTRACT FROM AUTHOR]

The article presents a study which determines organometallic cluster structure of lower molybdenum chlorides. The study shows that the structures resemble a distorted icosahedron where the 12-atom and central atom shell can be distinguished. It reveals that the best agreement having the experimental bond lengths was achieved for the carbon coordination by the triple bond.

A dinitrogen-bridged dimolybdenum-tetrachloride complex is prepared and reduced with Super-Hydride (LiBHEt3) to afford the corresponding dimolybdenum-dinitrogen complex together with the formation of molecular dihydrogen. This reaction proceeds via the ligand exchange of the coordinated dihydrogen generated in situ with molecular dinitrogen. [ABSTRACT FROM AUTHOR]

Abstract: The oxidative treatment of a suitable 1,3-diarylpropene precursor by MoCl5 causes a series of redox steps yielding a dimer of dibenzo[a,c]cycloheptene. After the oxidative aryl–aryl bond formation, a C,H activation occurs providing a tropylium intermediate. Upon aqueous workup the metal waste acts as reductive media generating the dimer in an almost quantitative manner. The oxidative generation of the tropylium species as well as the subsequent redox play by the metal waste is unique and unprecedented. The dimeric compound can be oxidatively cleaved and subsequently decarboxylated providing the key intermediate of a previous synthesis of metasequirin-B derivatives. [Copyright &y& Elsevier]