- Snythesis, characterization and thermal dissociation of cobalt(II) complexes of the photoproducts of octacyanomolybdate(IV) and -tungstate(IV) with ethylenediamine
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Photosubstituted mixed ligand complexes of Co(II) with irradiated solutions of Mo(CN)84- and W(CN)84- with ethylenediamine have been synthesized. The complexes have been isolated and characterized by their elemental analysis and IR spectroscopy. The assigned formulae are Co2[Mo(CN)2(C2H8N2) 2(OH)2]Cl4.2H2O I and Co[W(CN)2(C2H8N2) 2(OH)2]Cl2.2H2O II for Mo(IV) and W(IV) complexes, respectively. The IR peaks observed for both the complexes show N-H stretching, H-N-H bending and stretching vibrations of the C-N and C-C bonds. Depending on the nature of the absorption bands, complex I is assigned as -trans and complex II as -cis configuration. The thermal decomposition of these complexes has been studied by TG and DSC techniques. The reaction scheme for decomposition of each complex has been proposed. The activation energy (Ea), pre-exponential factor (A) and entropy of activation (ΔS#) have been calculated by employing the integral methods like Arrhenius, Coats-Redfern and Doyle. Enthalpy (ΔH) values for each transition are obtained from DSC data.
- Ali,Majid, Kowsar
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- Thermal, spectroscopic and kinetic characterization of reaction products of copper(II) chloride with photoproducts of octacyanocomplexes of Molybdenum(IV) and Tungsten(IV) with ethylenediamine
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The thermal dissociation of complexes formed by copper(II) chloride with photoproducts of M(CN)4-8 [where M=Mo or W] and ethylenediamine has been studied by thermogravimetry (TG), differential scanning calorimetry (DSC) and IR spectroscopy. The observed IR bands for different groups support the assigned composition. Both Mo(IV) and W(IV) show the same stoichiometric behaviour towards complex formation but a different decomposition behaviour. In case of Mo(IV) decomposition takes place in four steps with cyanide and oxide of copper and tetrachloro molybdenum(IV) as residue, while in case of W(IV) the decomposition occurs only in three steps up to 298°C. The copper cyanide along with tetrachloro tungstate(IV) is found as residue. DSC for Mo complex displays four transitions, two exothermic and two endothermic. In case of W, DSC displays three endothermic transitions corresponding to three decomposition steps with three different ΔH values. On the basis of TG and DSC, mechanism for decomposition of each complex has been proposed. Kinetic parameters like activation energy (Ea), frequency factor (A), entropy of activation (ΔS#) for each step has been calculated involving differential methods like Doyle, Coats and Redfern and Arrhenius. The heat of the reaction is obtained from DSC curves.
- Ali,Majid, Kowsar
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- Relaxation and electron transfer dynamics in bare and DTDCI sensitized MoS2 nanoclusters
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The trapping dynamics of photogenerated electron and holes in MoS2 nanoclusters using time resolved emission polarization and absorption spectroscopies were studied. The results indicated that emission from MoS2 band edge state were polarized and that from trapped electrons and holes were unpolarized. Results obtained from MoS2/DTDCI (diethylthiodicarbocyanine iodide) showed that electron emission occurs with a time constant of 12 ps.
- Chikan,Waterland,Huang,Kelley
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- Size-dependent spectroscopy of MoS2 nanoclusters
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The synthesis and characterization of 3.5, 4.5, and 8 nm diameter MoS2 nanoclusters are described. Each size is characterized by TEM images, electron diffraction, and optical spectroscopy. These nanoclusters can be synthesized directly or may be synthesized from samples of polydisperse nanoclusters. Obtaining larger or smaller discrete sizes from polydisperse samples indicates that these nanocluster sizes are thermodynamically favored, that is, these sizes correspond to free-energy minima. Electron diffraction and static spectroscopic results indicate that the particles are three atoms thick, specifically, single S-Mo-S trilayer disks. Static and time-resolved absorption and emission spectroscopy were used to determine the polarizations of the lowest energy allowed transitions in each case. We find that the 8 nm particles have a lowest energy absorption maximum at 473 nm that has mixed x - y and z polarizations, 4.5 nm particles have absorption maxima at 400 and 440 nm that are x - y and z polarized, respectively, and 3.5 nm particles have an absorption maximum at 362 nm that is z polarized. These results indicate that the polarization of the lowest observed transition is size-dependent and that the ordering of the lowest excited states changes as the particle size decreases.
- Chikan,Kelley
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- Synthesis and properties of MoCl4 complexes with thio- and seleno-ethers and their use for chemical vapour deposition of MoSe2 and MoS2 films
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Treatment of trans-[MoCl4(MeCN)2] with L (L = Me2S, Me2Se, THT, 1/2MeSCH2CH2SMe) in CH2Cl2 solution, or reaction of MoCl5 with excess L′ (L′ = nB
- Chang, Yao-Pang,Hector, Andrew L.,Levason, William,Reid, Gillian,Whittam, Joshua
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p. 2406 - 2414
(2018/02/20)
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- Novel benzyl-substituted molybdocene anticancer drugs
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From the reaction of 6-(p-methoxyphenyl) fulvene (1a), 6-(3,4-dimethoxyphenyl) fulvene (1b) and 6-(3,4,5-trimethoxyphenyl) fulvene (1c) with LiBEt3H, lithiated cyclopentadienide intermediates (2a-c) were synthesised. These intermediates were then transmetallated to molybdocene using MoCl4 (synthesized in situ) to yield the benzyl-substituted molybdocenes bis-[(p-methoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3a), bis-[(3,4-dimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3b), and bis-[(3,4,5-trimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3c). The molybdocene 3a was characterised by single crystal X-ray diffraction. All three molybdocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the human renal cell line Caki-1 in order to determine their IC50 values and compare them with the corresponding titanocene and vanadocene dichloride derivatives. Molybdocenes 3b-c were found to have the same IC50 values of 290 μM, while 3a yielded a value of 84 μM, respectively.
- Gleeson, Brendan,Claffey, James,Deally, Anthony,Hogan, Megan,Méndez, Luis Miguel Menéndez,Müller-Bunz, Helge,Patil, Siddappa,Tacke, Matthias
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p. 1831 - 1836
(2010/09/04)
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- Improved preparations of molybdenum coordination compounds from tetrachlorobis(diethyl ether)molybdenum(IV)
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The reduction of MoCl5 with metallic tin in diethyl ether provides a rapid and convenient entry to [MoCl4(OEt2)2] This compound can be transformed easily and in high yields into a variety of other useful synthon
- Stoffelbach, Fran?ois,Saurenz, Dirk,Poli, Rinaldo
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p. 2699 - 2703
(2007/10/03)
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- On tetrachlorophosphonium chlorometallates of rhenium and molybdenum: Syntheses, crystal structures, and magnetism of [PCl4]2[Re2Cl10] and [PCl4]3[ReCl6]2, and the magnetic properties of [PCl4]2[Mo2Cl10]
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MoCl4, ReCl4, and ReCl5 react with PCl5 in sealed glass ampoules at temperatures between 220° and 320° to [PCl4]2[Mo2Cl10] (1) [PCl4]2[Re2Cl10] (2), and [PCL4]3[ReCl6]2 (3). 2 crystallizes isotypically to the previously reported 1 and the respective titanium and tin containing analogues. The structure (triclinic, P1 Z = 1, a = 897.3(2), b = 946.0(2), c = 687.13(9) pm, α = 95.59(2)°, β = 95.80(2)°, γ = 101.07(2)°, V = 565.4(2) 106 pm3) is built of tetrahedral [PCl4]+ and edge sharing double octahedral [Re2Cl10]2- ions and can be derived from a hexagonal closest packing of Cl- ions with tetrahedral and octahedral holes partially filled by P(V) and Re(IV), respectively. 3 crystallizes isotypically to [PCL4]3[PCl6][MCl6] (M = Ti, Sn) (tetragonal, P 42/mbc, Z = 4, a = 1496.2(1), c = 1363.2(2) pm). Because no evidence was found for the presence of [PCl6]- ions, Re in 3 has to be of mixed valency with ReIV and ReV sharing the same crystallographic site. The structure can be derived from a cubic closest packing or alternatively from an only sparsely distorted body centered cubic arrangement of Cl- ions which is rarely found for anion arrays. The tetrahedral and octahedral holes are partially filled by PV and MIV/V, respectively. Magnetic measurements show all three compounds to be paramagnetic and confirm the oxidation state IV for Mo and Re in 1 and 2 and the mixed valence (IV/V) for Re in 3.
- Beck,Mueller-Buschbaum,Wolf
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p. 975 - 981
(2008/10/08)
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- Preparation et identification des produits de l'interaction Cl2-Mo a haute temperature (870-1160 deg C)
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The products resulting from the chlorine interaction with molybdenum powder in the range from 870 deg C to 1160 deg C, have been observed in the experimental conditions allowing to obtain eventually molybdenum coatings by means of chemical deposition of v
- Mezin, A.,Lepage, J.,Paulmier, D.
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p. 660 - 663
(2007/10/02)
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