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[Display omitted] • Synthesis of phosphorus free organic molybdenum additive. • Phosphorus free organic molybdenum additive greatly reduces wear volume. • The organic molybdenum additive has excellent anti-friction and anti-wear. • The lubrication mechanism of organic molybdenum additive was discussed. A phosphorus-free triazine-based organic molybdenum compound (DCDM) was designed and synthesized by using the click chemistry approach, and its friction-reducing and anti-wear properties were evaluated in PAO10 base oil. The results indicated that DCDM exhibited excellent tribological performance, with a reduction of approximately 35% in friction coefficient and about 46% in wear scar diameter, due to the synergy effect between Mo and S. Surface analysis by EDS and XPS revealed the formation of MoO 3 , Fe 2 (SO 4) 3 , FeS, and MoS 2 in the friction film. And it was furhter confirmed that the presence of MoS 2 in the friction film contributed most significantly to the enhancement of the friction-reducing and anti-wear properties of the developed triazine-based organic molybdenum compound in PAO10 base oil. [ABSTRACT FROM AUTHOR]

The aim of this mini review was to report the molybdenum compound intervention to control cancer disease. The intervention explains its roles and progress from inorganic molybdenum compounds via organomolybdenum complexes to its nanoparticles to control oesophageal cancer and breast cancer as case studies. Main contributions of molybdenum compounds as anticancer agents could be observed in their nanofibrous support with suitable physicochemical properties, combination therapy, and biosensors (biomarkers). Recent areas in anticancer drug design, which entail the uses of selected targets, were also surveyed and proposed. [ABSTRACT FROM AUTHOR]

The lubricating properties of two different organomolybdenum additives combined with ZDDP were evaluated for different tribopairs involving carbon-based coatings, hydrogenated DLC and nanocrystalline diamond NCD. Their performances were investigated using reciprocating linear tribometer and compared with the traditional additivation MoDTC/ZDDP. The highly sulfurised moly-trimer additive and organic molybdate ester additive displayed good friction reducing properties in comparison with traditional additivation MoDTC for all tribopairs tested, especially organic molybdate ester. XPS and ToF-SIMS surface analyses performed on the tribofilms formed with these different organomolybdenum additives showed the formation of MoS 2 /MoS 2− x O x species exhibiting a solid lubricant character, but preferentially on steel surfaces. HRTEM/EDS analyses confirmed the presence of MoS 2 /MoS 2− x O x sheets embedded inside an oxygen-rich amorphous matrix. This is different from the traditional additivation that leads to the polyphosphate/phosphate glass matrix. Organic molybdate ester is a sulfur- and phosphorus-free additive that appears particularly interesting for achieving low friction while minimizing the S content of the lubricant. [ABSTRACT FROM AUTHOR]

A family of low-valent molybdenum complexes supported by the pincer ligand PNMeP (PNMeP = MeN(CH2CH2PPh2)2) was prepared and characterized, including (PNMeP)Mo(C2H4)2, which contains an agostic interaction between the metal and the N-methyl substituent. This β-agostic C-H bond was cleaved by molybdenum and produced a cyclometalated molybdenum formate complex, (κ4-PNMeP)Mo(C2H4)(κ2-O2CH), upon exposure to CO2. This species serves as a promotor of CO2 hydrogenation to formate under basic conditions, a rare transformation for group VI metals. The performance of the precatalyst was enhanced with the addition of Lewis acid salts. [ABSTRACT FROM AUTHOR]

The cyclopentadienyl molybdenum carbonyl complexes [( η 5 -C 5 H 4 R)Mo(CO) 2 ( η 3 -C 3 H 5 )] and [( η 5 -C 5 H 5 )Mo(CO) 3 (CH 2 R)] (R = H, COOH) have been shown to promote acid-catalysed reactions in liquid phase, under moderate conditions. The catalytic alcoholysis of styrene oxide with ethanol at 35 °C gave 2-ethoxy-2-phenylethanol in 100% yield within 30 min for the dicarbonyl complexes and 3–6 h for the tricarbonyl complexes. Steady catalytic performances were observed in consecutive runs with the same catalytic solution, suggesting fairly good catalytic stability. In the second acid-catalysed reaction studied, the isomerization of α-pinene oxide at 55 °C gave campholenic aldehyde and trans -carveol in a total yield of up to 86% at 100% conversion. Chemoselectivity is shown to be solvent dependent. [ABSTRACT FROM AUTHOR]

Abstract: Compounds [Cp*2M2O5] (M = Mo, W) react with stoichiometric amounts of H2O2 (as a 30% w/w solution in water) and t BuOOH (TBHP, as a 70% w/w solution in decane) in MeCN solution to yield a variety of products as shown by the 1H NMR monitoring of the Cp* resonance. The reaction rate increases in the order W < Mo and TBHP < H2O2. While the total Cp* intensity remains constant when using stoichiometric amounts of oxidant, use of excess oxidant results in the ultimate total Cp* loss. From the decomposed solutions, crystals of [Cp*2Mo6O17] (1), (C5Me5O)[Cp*M6O18] (M = Mo, 2a; W, 2b), and (C5Me5O)2[Mo6O19] (3) were recovered and analyzed by X-ray diffraction. Catalytic cyclooctene epoxidation experiments with ( n Bu4N)2[M6O19] (M = Mo, W) in a 3:1 MeCN/toluene mixture at 55 °C using either aqueous H2O2 or TBHP/decane as oxidant revealed that these are not the active forms of the catalyst which is generated under the same conditions from [Cp*2M2O5], as reported in previous contributions from our group (Chem. Eur. J., 2010, 16, 9572–9584; Eur. J. Inorg. Chem., 2013, 2728–2735). Further catalytic studies using aged [Cp*2Mo2O5]/TBHP and [Cp*2W2O5]/H2O2 solutions show a small loss of activity (<50% in one week) attesting the robustness of the non-organometallic catalytically active species that is generated from the decomposition of [Cp*2M2O5]. These results cast doubts on the role of cyclopentadienyl as a supporting ligand for stable olefin epoxidation catalysts. [Copyright &y& Elsevier]

Due to the increasing demand of low emission and fuel economy, friction modifiers have been widely used in lubricating compositions to adjust friction and wear properties of lubricants. Recent achievements in the application of friction modifiers for liquid lubricants (2007-present) are reviewed in this paper. There are three types of friction modifiers for liquid lubricants: organomolybdenum compounds, organic friction modifiers, as well as nanoparticles. The tribological properties and lubrication mechanisms of these friction modifiers are discussed. The problems and some suggestions for the future directions of research on friction modifiers are proposed. [ABSTRACT FROM AUTHOR]

A novel uncatalyzed reaction betweenTpMo(CO)2(5-trifluoroacetoxy-η3-5,6-dihydropyranyl/dihydropyridinyl)complexes and electron-rich arenes/olefins is reported. The reactionproceeds under mild reaction conditions so that a variety of functionalgroups are tolerated. Combined with a stereospecific annulative demetalation,the new reaction provides a rapid access to polycyclic alkaloid structures.The sequential protocol was used to prepare analogues of the antimalarialagent isofebrifugine. [ABSTRACT FROM AUTHOR]

The aqueous chemistry of Cp 2MoCl 2 was investigated utilizing density functional methodology in conjunction with a conductor-like polarizable continuum solvation model. A stepwise process has been found for hydrolysis of Cp 2MoCl 2 in which the second Cl − loss is more energy-demanding than the first as experimentally found. Interestingly, the Cl − loss from [Cp 2Mo(H 2O)Cl] + can occur either directly or after deprotonation. Both mechanisms are competitive when the pH effect is not considered in the computations, but the latter is the most favored when considering a physiological pH. We corroborate that [Cp 2Mo(OH)(H 2O)] + is the active species and also show why [Cp 2Mo(OH)] + is the reactive form in Cp 2MoCl 2(aq)-promoted reactions. Dimerization of [Cp 2Mo(OH)(H 2O)] + occurs via a relatively low Gibbs energy barrier in water solution of 11.8 kcal mol −1, being the inactive dimer [Cp 2Mo(μ-OH) 2MoCp 2] 2+ clearly more stable than the two separate monomers. This explains why the rate of the Cp 2MoCl 2(aq)-promoted reactions is adversely affected. Besides, we also propose a reinterpretation of the assignment of the experimental p Ka 2.2 ± 0.2 recently found for hydrolysis of Cp 2MoCl 2(aq) and suggest a revision of the equilibrium scheme proposed in this chemistry. Therefore, the present study provides a more complete insight about this kind of processes that can help in designing more efficient catalysts for organic transformations and, particularly, new functionalized molybdocenes to increase/enhance their biological activity. [ABSTRACT FROM AUTHOR]

Abstract: A novel Dy(III)-based organodiphosphonate-functionalized polyoxomolybdate [NH2(CH3)2]3{[Dy(DMF)2(H2O)4]3[Dy(DMF)3{(Mo3O8)(O3PCOCH3PO3)}3]2}∙6DMF·2H2O (1) (DMF=N,N-Dimethylformamide) has been synthesized and characterized by elemental analysis, IR spectrum, thermogravimetric analysis (TG), UV spectroscopy, fluorescence spectroscopy and single-crystal powder X-ray diffraction (PXRD). Compound 1 is composed of two monocapped [Dy(DMF)3{(Mo3O8)(O3PCOCH3PO3)}3]6− subunits and three [Dy(DMF)2(H2O)4]3+ coordination cations, which contain an internal capsule. The UV spectra indicate that compound 1 is stable in the pH range of 2.76–4.75. [Copyright &y& Elsevier]

Molybdenum and tungsten bispyrrolidealkylidene complexes thatcontain a 2,6-dimesitylphenylimido (NAr*) ligand have been prepared,in which the pyrrolide is the parent pyrrolide or 2,5-dimethylpyrrolide.Monoalkoxide pyrrolide (MAP) complexes were prepared through additionof 1 equiv of an alcohol to the bispyrrolide complexes. MAP compoundsthat contain the parent pyrrolide (NC4H4–) are pyridine adducts, while those that contain 2,5-dimethylpyrrolideare pyridine free. Molybdenum and tungsten MAP 2,5-dimethylpyrrolidecomplexes that contain O-t-Bu, OCMe(CF3)2, orO-2,6-Me2C6H3ligands were foundto have approximately equal amounts of synand antialkylidene isomers, which allowed a study of the interconversionof the two employing 1H–1H EXSY methods.The Keqvalues ([syn]/[anti]) are all 2–3 orders of magnitude smaller thanthose observed for a large number of Mo bisalkoxide imido alkylidenecomplexes, as a consequence of the destabilization of the synisomer by the sterically demanding NAr* ligand. Therates of interconversion of synand antiisomers were found to be 1–2 orders of magnitude faster forW MAP complexes than for Mo MAP complexes. [ABSTRACT FROM AUTHOR]

Abstract: The cyclopentadienyl molybdenum tricarbonyl complex CpMo(CO)3(CH2–pC6H4–CO2CH3) (1) (Cp = η 5-C5H5) and its 1:1 inclusion complexes with heptakis(2,6-di-O-methyl)-β-cyclodextrin (1@DIMEB) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (1@TRIMEB) were prepared and characterized by elemental and thermogravimetric analyses, powder X-ray diffraction, NMR, FT-IR and Raman spectroscopy. All three compounds were investigated as catalyst precursors for olefin epoxidation using cis-cyclooctene (Cy) as a model substrate, a reaction temperature of 55 °C, and different types of oxidants (tert-butylhydroperoxide in decane (TBHPdec) or in water (TBHPaq), and aqueous hydrogen peroxide). With the aim of facilitating recycling of the homogeneous catalytic systems, different solvent mixtures were tested: biphasic liquid–liquid solvent systems [(water, glycerol, ionic liquid)–(n-hexane, α,α,α-trifluorotoluene (TFT), iso-butyl methyl ketone)], and in some cases no cosolvent was added. Excellent epoxide selectivity (100%) was observed for all tested catalytic systems. An example of an interesting catalytic system is that of 1@TRIMEB/TBHPaq/TFT/H2O since the catalyst can be easily separated in the form of an aqueous solution, by decantation, from the organic phase containing the reaction products and recycled. [Copyright &y& Elsevier]

Abstract: The molybdenum tricarbonyl complexes [Mo(CO)3(HC(3,5-Me2pz)3)] (1) and [Mo(CO)3(HC(pz)3)] (2) (HC(3,5-Me2pz)3 =tris(3,5-dimethyl-1-pyrazolyl)methane, HC(pz)3 =tris(1-pyrazolyl)methane) were obtained in good yields by the microwave-assisted reaction of Mo(CO)6 with the respective organic ligand. Complete oxidative decarbonylation of 1 and 2 was achieved by reaction with excess tert-butylhydroperoxide (TBHP) in 1,2-dichloroethane at 55°C. For complex 1, the (μ2-oxo)bis[dioxomolybdenum(VI)] hexamolybdate of composition [{MoO2(HC(3,5-Me2pz)3)}2(μ2-O)][Mo6O19] (3) was obtained in good yield, and its structure was determined by single crystal X-ray diffraction. The compound (4) obtained by oxidative decarbonylation of 2 was not unambiguously identified, but may be chemically analogous to 3. Compounds 1–4 were examined for the first time as homogeneous (pre)catalysts for the epoxidation of olefins with TBHP, using different types of cosolvents at 55°C. During the catalytic reactions 1 and 2 transform in situ into 3 and 4, respectively, and the latter two are fairly stable catalysts. Catalytic tests and characterization studies of the recovered catalysts were carried out in an attempt to understand the kinetic differences observed between the compounds prepared in situ during the catalytic reaction and those prepared prior to the catalytic reaction, from the same precursor complex. [Copyright &y& Elsevier]

A series of Cp2Mo(dithiolene) and Cp2Mo(diselenolene) complexes containing N-alkyl-1,3-thiazoline-2-thione-4,5-dithiolate ligand (R-thiazdt, R = Me, Et, CH2CH2OH) and N-alkyl-1,3-thiazoline-2-thione-4,5-diselenolate ligand (R-thiazds, R = Me, Et) have been synthesized. These heteroleptic molybdenum complexes have been characterized by electrochemistry, spectroelectrochemistry, and single crystal X-ray diffraction. They act as very good electron donor complexes with a first oxidation potential 200 mV lower than in the prototypical Cp2Mo(dmit) complex and exhibit almost planar MoS2C2 (or MoSe2C2) metallacycles. All five complexes formed charge transfer salts with a weak (TCNQ) and a strong acceptor (TCNQF(4)), affording ten different charge-transfer salts, all with 1:1 stoichiometry. Crystal structure determinations show that the S/Se substitution in the metallacycle systematically affords isostructural salts, while the Cp2Mo(R-thiazdt) complexes with R equals ethyl or CH2CH2OH can adopt different structures, depending on the involvement of the hydroxyl group into intra- or intermolecular hydrogen bonding interactions. Magnetic susceptibility data of the salts are correlated with their structural organization, demonstrating that a face-to-face organization of the Me-thiazdt (or Me-thiazds) ligand favors a strong antiferromagnetic interaction, while the bulkier R = Et or R = CH2CH2OH substituents can completely suppress such intermolecular interactions, with the added contribution of hydrogen bonding to the solid state organization. [ABSTRACT FROM AUTHOR]

The decomposition of 1-chloro-4-ethylbenzene under UV irradiation (λ = 253.7 nm) in the presence of dioxygen and the dioxomolybdenum(VI)dichloro[4,4′-dicarboxylato-2,2′-bipyridine] complex anchored on the TiO surface has been investigated. The catalytic cycle includes the photostimulated transfer of the oxo-oxygen atom from the surface dioxomolybdenum(VI) complex to the substrate followed by the oxidation of reduced Mo(IV) by dioxygen (in the absence of UV irradiation). The major reaction products are chlorobenzene, CO, and HO. Chlorobenzene results from the photocatalytic decomposition of intermediate 4′-chloroacetophenone under the reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports synthesis and structural elucidation of three new 2:1 molybdenum–EDTA complex based solids: [{Na2(H2O)6}{Mo2O6(H2EDTA)}]·2H2O (1), [{Na4(H2O)8}{Mo2O6(EDTA)}] (2) and [(H2TEMED)Mo2O6(H2EDTA)]·H2O (3). Retrosynthesis of the phases crystallized from the system Na2H2EDTA·2H2O−Na2MoO4·H2O or TEMED-MoO3 provides molecular insights by interpreting the crystal packing in terms of the intermolecular interactions between tectons. 1 and 2 are examples of concentration-dependent crystallization. 3 is the first example based on Mo–EDTA with organic as counter cation. In 1 and 2, the Mo–EDTA complex is coordinated through water-bridged sodium hydrates while in 3 the 2:1 complex interacts with organic counter cation through hydrogen bonding. Crystal data: 1, Monoclinic, space group P21 /c, a =8.5086(9)Å, b =11.5536(12)Å, c =13.3844(14)Å, =92.713(2)°, Z =4; 2, Monoclinic, space group P21 /c, a =11.892(8)Å, b =6.587(5)Å, c =17.155(12)Å, =108.794(11)°, Z =4; 3, Monoclinic, space group P2/c, a =14.549(4)Å, b =6.9153(17)Å, c =15.471(4)Å, =112.843(4)°, Z =2. [Copyright &y& Elsevier]

Abstract: Monomeric organomolybdenum carbonyl complexes of general formula [(η5-C5R5)Mo(CO)3X] (R=H, CH3, CH2Ph; X=alkyl, halide) are known to be pre-catalysts for olefin epoxidation. In this work, the application of a fluorinated complex, [CpMo(CO)3CF3] (Cp=η5-C5H5), is reported. With hexafluoroisopropanol as a solvent, a turnover frequency (TOF) of >6300h−1 was achieved in the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidant. So far, only ansa compounds of formula [Mo(η5-C5H4(CH(CH2) n )-η1-CH)(CO)3] are known to deliver better performances in catalytic epoxidation reactions at room temperature. [CpMo(CO)3CF3] was also applied in 2-phase catalytic epoxidation reactions. The high stability of the oxidised species allows catalyst recycling for multiple catalytic runs without significant loss of activity. Besides, the fluorinated complex enables – at this stage preliminary – mechanistic 19F NMR studies, indicating the nature of the catalytically active Mo-species, which has been an unresolved subject for some time. [Copyright &y& Elsevier]

The title complex was formed instantaneously by reacting[Mo2Cp2(μ-CPh)(μ-PCy2)(μ-CO)]with [FeCp2]BF4in the presence of diphenyldisulfide, but it could not be isolated as a pure material. It mostlikely displays bridging phosphide and thiolate ligands and essentiallyterminal carbonyl (Mo–C = 1.987 Å) and carbyne (Mo–C= 1.820 Å) ligands, according to density functional theory calculations.In solution this complex released CO spontaneously to yield the 30-electroncomplex [Mo2Cp2(μ-CPh)(μ-PCy2)(μ-SPh)]BF4(Mo–Mo = 2.4772(6) Å),and attempts to crystallize it at low temperature yielded insteadthe electron-precise aquo derivative [Mo2Cp2(μ-CPh)(μ-PCy2)(μ-SPh)(CO)(OH2)]BF4(Mo–Mo = 2.7820(4) Å). The additionof CO induced the coupling between the carbyne and phosphide ligands,to yield the tricarbonyl phosphinocarbene complex [Mo2Cp2(μ-η1:η1,κ1-CPhPCy2)(μ-SPh)(CO)3]BF4(Mo–Mo = 2.928(1) Å). This coupling process was reversible,since the latter complex could be decarbonylated stepwise by thermalmethods, to give first the 32-electron phosphinocarbene derivative[Mo2Cp2(μ-η1:η1,κ1-CPhPCy2)(μ-SPh)(CO)2]BF4(Mo–Mo = 2.7863(4) Å) and eventuallyyielding [Mo2Cp2(μ-CPh)(μ-PCy2)(μ-SPh)]BF4via the title complex. In contrastto this behavior, the reaction of the title complex with CNtBu did not induce a P–C coupling process,but eventually led to the displacement of the thiolate ligand to givethe dication trans-[Mo2Cp2(μ-CPh)(μ-PCy2)(CNtBu)4]2+via the bis(isocyanide) complex cis-[Mo2Cp2(μ-CPh)(μ-PCy2)(μ-SPh)(CNtBu)2]BF4, with thesedifferences being probably steric in origin. [ABSTRACT FROM AUTHOR]

Density functional calculations have been performed to rationalize the oxidation of carbon monoxide by [Cp2Mo(OH)(OH2)]+ (Cp = η5-C5H5) to give carbon dioxide and [Cp2MoH(CO)]+. Our results show that the intramolecular nucleophilic mechanism is the most favored both in the gas phase and in water solution, which is in good agreement with experimental results. The rearrangement that takes place during the nucleophilic hydroxide attack with a simultaneous hydrogen migration to the molybdenum center is the rate-determining step in the gas phase with a Gibbs energy barrier of 48.7 kcal mol-1. In water medium, however, this combined process takes place separately and passes through a new [Cp2Mo(COOH)]+-type intermediate. The inclusion of one explicit water molecule in the continuum solvent model computations plays a crucial role to make the nucleophilic hydroxide attack the rate-determining step in the overall reactive process with a Gibbs energy barrier in solution of 21.2 kcal mol-1. Besides this, our results have allowed us to rationalize the relatively low conversion of [Cp2Mo(OH)(OH2)]+ that was experimentally found. [ABSTRACT FROM AUTHOR]

Abstract: A novel, highly efficient and reusable molybdenum based catalyst has been synthesized by covalent grafting of 2,6-diacetylpyridine-monosalicyloylhydrazone onto functionalized silica followed by complexation with MoO2(acac)2, and the resulting organic–inorganic hybrid material was found to be highly effective catalyst for oxidation of various sulfides and olefins to their corresponding sulfoxides/sulfones and epoxides, respectively. The catalyst was characterized by elemental analysis (CHN), diffuse reflectance UV–Vis, 13C CPMAS NMR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area analysis, energy dispersive X-ray fluorescence (ED-XRF), Fourier-transform infrared (FT-IR) and atomic absorption spectroscopy (AAS). Mild reaction conditions, high turnover frequency, high selectivity, easy recovery and reusability of the catalyst render the present protocol very useful to address the industrial needs and environmental concerns. [Copyright &y& Elsevier]

Abstract: A new kind of sulfur- and phosphorus-free organomolybdenum oil-based additive N, N-bis (2-hydroxyethyl)-dodecanamide molybdate (NNDM) was prepared. Its tribological performances as additive in base oil 150SN were examined on a four-ball tester, and compared with those of ZDDP and MoDTC under boundary lubrication condition. The tribofilm NNDM generated on the worn surface was analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results showed that NNDM blend oil exhibited excellent load-carrying capacity, significantly reduced friction coefficient and wear rate of worn surface, which could be attributed to high amount of long-chain alkylamide and MoOx in NNDM tribofilm. [Copyright &y& Elsevier]

Abstract: A complex of the general formula Mo2(bpy)2(DCQX)(CO)3, (where DCQX and bpy are 6,7-dichloroquinoxaline-2,3-dione and 2,2′-bipyridine), was synthesized in two steps starting with the reaction of Mo(CO)6 with bpy then followed by the addition of DCQX ligand. Initial characterization based on the elemental and mass analyses has suggested three possible structures (1–3). In the three suggested structures the DCQX ligand bonded to two Mo(0) metal centers; to one Mo metal through its C=O functional groups and the other through the aromatic ring forming η6-arene type. In structure 1 the DCQX ligands bonded to (bpy)2Mo and Mo(CO)3 moieties, whereas in the other structures the DCQX ligands bonded to Mo(bpy)(CO) and cis-(bpy)(CO)2Mo (2) or trans-(bpy)(CO)2Mo (3) moieties. The IR studies were useful in assigning the coordination modes of the ligands especially in the carbonyl region of the spectrum. 1H NMR studies in DMSO-d6 displayed typical patterns corresponding to cis-(bpy)2M moiety. The electronic absorption spectrum of the complex revealed two bands assignable to Mo(dπ)→arene(π∗) and Mo(dπ)→bpy(π∗) MLCT transitions. The thermogravimetric analysis gave more insight into the composition and the thermal stability of the complex. The structural and vibrational behaviors of the Mo2(bpy)2(DCQX)(CO)3 complex have been elucidated using semiempirical parameterized PM3 method. Although, both DCQX ligand and the molybdenum complex showed antimicrobial activities, the complex inhibition to the studied microorganisms was higher. [Copyright &y& Elsevier]

Abstract: The reactions of cis-[Mo(η3-methallyl)Cl(CO)2(NCMe)2] and 0.5 equivalents of tetra-n-butylammonium salts of pyrazolate (pz), 3,5-dimethylpyrazolate (dmpz) or indazolate (inz) lead to NnBu4[{Mo(η3-methallyl)(CO)2(μ-Cl)}2(μ-pz*)] (pz* = pz, dmpz, inz), where the bridging pyrazolato is coordinated trans to the allyl group and both bridging chlorido ligands are coordinated trans to the carbonyls. [Copyright &y& Elsevier]

Reactions of the thiocarbamoyl-molybdenum complex [Mo(CO)2(η2-SCNMe2)(PPh3)2Cl] 1, and ammonium diethyldithiophosphate, NH4S2P(OEt)2, and potassium tris(pyrazoyl-1-yl)borate, KTp, in dichloromethane at room temperature yielded the seven coordinated diethyldithiophosphate thiocarbamoyl-molybdenum complexe [Mo(CO)2{η2-S2P(OEt)2}(η2-SCNMe2)(PPh3)] β-3, and tris(pyrazoyl-1-yl)borate thiocabamoyl-molybdenum complex [Mo(CO)2(η3-Tp)(η2-SCNMe2)(PPh3)] 4, respectively. The geometry around the metal atom of compounds β-3 and 4 are capped octahedrons. The α- and β-isomers are defined to the dithio-ligand and one of the carbonyl ligands in the trans position in former and two carbonyl ligands in the trans position in later. The thiocabamoyl and diethyldithiophosphate or tris(pyrazoyl-1-yl)borate ligands coordinate to the molybdenum metal center through the carbon and sulfur and two sulfur atoms, or three nitrogen atoms, respectively. Complexes β-3 and 4 are characterized by X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

Reactions of the thiocarbamoyl-molybdenum complex [Mo(CO)2(η2-SCNMe2)(PPh3)2Cl] 1, and ammonium diethyldithiophosphate, NH4S2P(OEt)2, and potassium tris(pyrazoyl-1-yl)borate, KTp, in dichloromethane at room temperature yielded the seven coordinated diethyldithiophosphate thiocarbamoyl-molybdenum complexe [Mo(CO)2{η2-S2P(OEt)2}(η2-SCNMe2)(PPh3)] β-3, and tris(pyrazoyl-1-yl)borate thiocabamoyl-molybdenum complex [Mo(CO)2(η3-Tp)(η2-SCNMe2)(PPh3)] 4, respectively. The geometry around the metal atom of compounds β-3 and 4 are capped octahedrons. The α- and β-isomers are defined to the dithio-ligand and one of the carbonyl ligands in the trans position in former and two carbonyl ligands in the trans position in later. The thiocabamoyl and diethyldithiophosphate or tris(pyrazoyl-1-yl)borate ligands coordinate to the molybdenum metal center through the carbon and sulfur and two sulfur atoms, or three nitrogen atoms, respectively. Complexes β-3 and 4 are characterized by X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

The reactivity patterns of a series of molybdenum silylhydrido complexes, [MoH3{[Ph2PCH2CH2P(Ph)C6H4-o]2(R)Si-P,P,P,P,Si}] (2a, R = Ph; 2b,R = C6F5; 2c, R = 4-Me2NC6H4; 2d, R = cyclohexyl; 2e, R = n-C6H13), towardelectrophilic materials, including dioxygen, carbon dioxide, carboxylicacids, and triflic acid, have been explored. The influence of substituentsdirectly attached to the Si atom in the quintuply chelating diphosphine–silylligands during the course of the reactions has been studied in detail.Complexes 2a–creact readily withdioxygen at ambient temperature, yielding η2-O2complexes 3a–c, in whichthe dioxygen ligand ligates at the site opposite to the Si atom. Single-crystalX-ray studies have established that the Mo–O distance of 3a, which contains a phenyl-substituted Si fragment, is significantlylonger than that found in common η2-O2complexes, in which the sizes of the central atoms are nearly equalto that of Mo as a consequence of the strong trans influence of thesilyl ligand. In contrast, the replacement of the phenyl group ona Si fragment by an electron-withdrawing perfluoro phenyl group, asin 3b, gives rise to a dramatic decrease in the transinfluence. Treatment of 2a–cwith2 equiv of carboxylic acids, such as formic acid, acetic acid, andbenzoic acid, readily leads to the formation of carboxylato molybdenumcomplexes, in which the carboxylate ligand coordinates to the metalin a monodentate mode. The resulting formato complex 4a1can also be derived from the insertion of CO2into theMo–H bond of 2a. In addition, complexes 2a,c,emediate the catalytic carbondioxide hydrogenation. The activity of the catalysts depends dramaticallyon the electronic effects of the substituents attached to the Si atom;electron-donating substituents lead to an increase in the catalyticactivity. Reactions of complexes 2a,dwithtriflic acid yield highly labile triflato complexes, which can befurther treated with aqueous NaOH to give hydroxo complexes 5a,d, respectively. The molecular structure of 5dhas been determined by single-crystal X-ray diffraction.The reactivities of 2a–eare discussedin comparison with those of the parent complex [MoH4(dppe)2] (1; dppe = Ph2PCH2CH2PPh2). [ABSTRACT FROM AUTHOR]

The successive treatment of [Mo(CBr)(CO)2{HB(pzMe2)3}] (1; pz =pyrazol-1-yl) with nBuLi and B(OR)3(R = Me, iPr) affords,via the lithiocarbyne complex [Mo(CLi)(CO)2{HB(pzMe2)3}] (2), the boratocarbynes Li[Mo{CB(OMe)3}(CO)2{HB(pzMe2)3}] (R =Me, Li[3a]; R = iPr, Li[3b]). The salt Li[3b] readily eliminates LiOiPr to afford the neutral boryl carbyne [Mo{CB(OiPr)2}(CO)2{HB(pzMe2)3}] (4b). The analogous boryl carbyne [Mo{CB(OMe)2}(CO)2{HB(pzMe2)3}] (4a) on treatment with K[HF2] and 18-crown-6 (18C6)provides the structurally characterized difluoro(methoxy)boratocarbynesalt [K(18C6)][Mo(CBF2OMe)(CO)2{HB(pzMe2)3}] ([K(18C6)][6]). [ABSTRACT FROM AUTHOR]

Seven bipyridine adducts of molybdenum imido alkylidenebispyrrolidecomplexes of the type Mo(NR)(CHCMe2R′)(Pyr)2(bipy) (1a–1g; R = 2,6-i-Pr2C6H3(Ar), adamantyl(Ad), 2,6-Me2C6H3(Ar′), 2-i-PrC6H4(AriPr), 2-ClC6H4(ArCl), 2-t-BuC6H4(ArtBu), and 2-MesitylC6H4(ArM), respectively; R′ = Me, Ph) have been prepared using threedifferent methods. Up to three isomers of the adducts are observedthat are proposed to be the trans- and two possible cis-pyrrolide isomers of syn-alkylidenes.Sonication of a mixture containing 1a–1g, HMTOH (2,6-dimesitylphenol), and ZnCl2(dioxane) ledto the formation of MAP species of the type Mo(NR)(CHCMe2R′)(Pyr)(OHMT) (3a–3g). DCMNBD(2,3-dicarbomethoxynorbornadiene) is polymerized employing 3a–3gas initiators to yield >98% cis,syndiotacticpoly(DCMNBD). Attempts to preparebipy adducts of bisdimethylpyrrolide complexes led to the formationof imido alkylidyne complexes of the type Mo(NR)(CCMe2R′)(Me2Pyr)(bipy) (Me2Pyr = 2,5-dimethylpyrrolide; 4a–4g) through a ligand-induced migrationof an alkylidene α proton to a dimethylpyrrolide ligand. X-raystructures of Mo(NAr)(CHCMe2Ph)(Pyr)2(bipy)(1a), Mo(NAriPr)(CHCMe2Ph)(Pyr)(OHMT) (3d), Mo(NAr)(CCMe2Ph)(Me2Pyr)(bipy) (4a), the NAr′ analogof 4a(4c), and Mo(NArT)(CCMe3)(Me2Pyr)(bipy) (ArT= 2-(2,4,6-i-Pr3C6H2)C6H4; 4g) showed normal bond lengthsand angles. [ABSTRACT FROM AUTHOR]

Abstract: The potential application of metallocene complexes into the cancer research was established by the pioneer work of Köpf-Maeir and Köpf in the late 1970s. The combination of organometallic chemistry and biochemistry created a new research area: bioorganometallic chemistry. Bioorganometallic chemistry has developed rapidly in the last thirty years leading to application of organometallic species into diagnostic, sensors, immunoassays and anticancer research among others. This review focuses on the bioorganometallic chemistry of molybdenocene dichloride and its derivatives as metal-based anticancer drugs. The anticancer properties of molybdenocene dichloride and its derivatives are described as well as the mechanism of action, aqueous and coordination chemistry, and molybdenocene–biomolecule interactions. [Copyright &y& Elsevier]

The reactions of R2P—P(SiMe3)Li (R = tBu, iPr2N) with [Cp2MoCl2] yield terminal phosphanylphosphido complexes formally via the insertion of the phosphinidene P-atom into the C—H bond of a cyclopentadienyl ring and the migration of the hydrogen atom or SiMe3 moiety to the molybdenum centre. Solid state structures of [Cp(C5H4P—PtBu2)MoH], [Cp(C5H4P—PtBu2)Mo(SiMe3)] and [Cp{C5H4P—P(NiPr2)2}Mo(SiMe3)] were established by single crystal X-ray diffraction. The proposed reaction path is supported by the results of NMR studies and DFT calculations. [Copyright &y& Elsevier]

Abstract: The reaction of the benzoylhydrazone of 2-hydroxybenzaldehyde (H2L) with [MoO2(acac)2] proceeds smoothly in refluxing ethanol to afford an orange complex [MoO2L(C2H5OH)] (1). The substrate binding capacity of 1 has been demonstrated by the formation and isolation of two mononuclear [MoO2L(Q)] {where Q=imidazole (2a) and 1-methylimidazole (2b)} and one dinuclear [(MoO2L)2(Q)] {Q=4,4′-bipyridine (3)} mixed-ligand oxomolybdenum complex. All the complexes have been characterized by elemental analysis, magnetic and spectroscopic (IR, UV–Vis and NMR) measurements. The molecular structures of all the oxomolybdenum(VI) complexes (1, 2a, 2b and 3) have been determined by X-ray crystallography. In each complex, the dianionic planar ligand is coordinated to the metal centre via one enolate oxygen, one phenolate oxygen and an azomethine nitrogen atom. The complexes have been screened for their antibacterial activity against Escherichia coli, Bacillus and Pseudomonas aeruginosa. The minimum inhibitory concentration of these complexes and their antibacterial activity indicates that compounds 2a and 2b are potential lead molecules for drug designing. [Copyright &y& Elsevier]

Abstract: Molybdenum (oxy)carbonitrides of different compositions have been prepared from hexamethylenetetramine molybdate and ethylenediamine molybdate precursors and the reactivity of the lattice carbon and nitrogen species within them has been determined by temperature programmed reduction and thermal volatilisation studies. Nitrogen is found to be much more reactive than carbon and the nature of its reactivity is influenced by composition with the presence of carbon enhancing the reactivity of nitrogen. The difference in reactivity observed indicates that molybdenum carbonitrides are not suitable candidates as reagents for which the simultaneous loss of nitrogen and carbon from the lattice would be desirable. [Copyright &y& Elsevier]

Abstract: Eight new crystal structures of sulfur-bridged dinuclear molybdenum(V) complexes with l-cysteine ligands, [Mo2(μ-S)2O2(cys)2]2− (1), were determined by changing the counter cations (K+, Ca2+, Sr2+, Mn2+, Ni2+, Cd2+, and Pb2+, where Mn2+ gave two kinds of crystal structures): K2[Mo2O2S2 (cys)2]·5H2O (1-K), Ca[Mo2O2S2 (cys)2]·8H2O (1-Ca), Sr[Mo2O2S2(cys)2]·6H2O (1-Sr), Mn[Mo2O2S2(cys)2]·12H2O (1-MnA), Mn[Mo2O2S2(cys)2]·7H2O (1-MnB), Ni[Mo2O2S2 (cys)2]·14H2O (1-Ni), Cd[Mo2O2S2(cys)2]·2H2O (1-Cd), and Pb[Mo2O2S2(cys)2]·2H2O (1-Pb). The eight crystal structures and two with other counter cations (Na2[Mo2O2S2(cys)2]·4H2O (1-Na) and Zn[Mo2(μ-S)2O2(cys)2]·2H2O (1-Zn)) so far reported were compared. The structures vary considerably by changing the counter cations, while few remarkable differences were observed with regard to the dimensions in the complex anion 1. There are four kinds of linkages: (1) one-dimensional zigzag chains appear in 1-Na, 1-Zn, 1-Cd, and 1-Pb; (2) a two-dimensional linkage appears in 1-K; (3) the cation and anion are directly linked, but they are separated from other cation–anion groups in 1-MnA; (4) the cation and anion are separated in 1-Ca, 1-Ni, 1-Sr, and 1-MnB. A good relationship exists between the coordination modes of metal cations and solubility of the corresponding metal sulfides. The coordination modes of metals are divided into two groups: Group 1: metal ions (Na+, K+, Sr2+, Ca2+, Mn2+(two kinds of crystals), and Ni2+) whose sulfides have large or medium solubility in water bind to oxygen (the carbonyl oxygen of cysteine, the terminal oxygen of Mo=O, and/or water); Group 2: metal ions (Zn2+, Cd2+, and Pb2+) whose sulfides have small solubility bind to cysteine sulfur. The HSAB principle explains the relationship. [Copyright &y& Elsevier]

Abstract: This work reports the ligational behavior of the neutral bidentate chelating molecule 2-(3,5-dimethyl pyrazol-1-yl) benzothiazole towards the oxomolybdenum(V) center. Both mononuclear complexes of the type MoVOX3L and binuclear complexes of the formula MoV 2O4X2L2 (where X=Cl, Br) are isolated in the solid state. The complexes are characterized by elemental analyses, various spectroscopic techniques (UV–Vis IR), magnetic susceptibility measurement at room temperature, and cyclic voltammetry for their redox behavior at a platinum electrode in CH3CN. The mononuclear complexes MoVOX3L are found to be paramagnetic while the binuclear complexes Mo2O4X2L2 are diamagnetic. Crystal and molecular structure of the ligand and the dioxomolybdenum complex MoVIO2Br2L (obtained from the complex MoOBr3L during crystallization) have been solved by single crystal X-ray diffraction technique. Relevant DFT calculations of the ligand and the complex MoVIO2Br2L are also carried out. [Copyright &y& Elsevier]

Abstract: The short chain alkoxycarbonyl complexes of molybdenum, [PPN][Mo(CO)5(COOR)], [R=CH3, CH2CH3 and CH(CH3)2], have been synthesized by the addition of [Mo(CO)6] to a refluxing solution of [PPN][OR] in different alcohol solvents under a CO atmosphere. In the absence of CO, metal alkoxide complexes [Mo(CO)5(OR)]− (R=CH2CH3 and CH(CH3)2) were formed. These new alkoxycarbonyl complexes were characterized by IR, 1H and 13C NMR spectroscopy, melting point and elemental analysis. When the CH3CN solution of the compounds [PPN][Mo(CO)5(COOCH(CH3)2)] and [PPN][Mo(CO)5(OCH(CH3)2)] were exposed to UV light the compounds decomposed to form the cluster compound [PPN]2[Mo6O19]. The tetraethylammonium derivative, [Et4N][Mo(CO)5(COOCH3)], prepared from [Et4N][OCH3] and Mo(CO)6 in methanolic solution also decomposed in CH3CN to form the new dark brown crystalline molybdenum oxo-cluster [Et4N]2[Mo4O13]. The compound crystallizes in the monoclinic form with a space group of P 21/n. Addition of [Ph4As][OCH(CH3)2] to Mo(CO)6 in a ratio of 4:1 results in the formation of the bis(alkoxycarbonyl) complex, [Ph4As]2[Mo(CO)4{(COOCH(CH3)2)2}]. The reaction of the methoxycarbonyl complex, [PPN][Mo(CO)5(COOCH3)] with synthesis gas in methanol at 125°C gave methyl formate, formic acid and Mo(CO)6. The same reaction as above in THF yielded methyl formate, methanol and formic acid. [Copyright &y& Elsevier]

Abstract: Reduction of [Mo2O2(μ-S)2(H2O)6]2+ with [Re(CO)5Cl] in 2М HCl at 160°C produces condensation of binuclear clusters with the formation of the{Mo3(μ3-S)(μ-O)3}4+ species, which was isolated and structurally characterized as {[Mo3(μ3-S)(μ2-O)3(H2O)6Cl3]2CB[6]}Cl2·10.88H2O (2) (CB[6]=C36H36N24O12) and [Mo3(μ3-S)(μ2-O)3(acac)3(py)3]PF6·2C6H5CH3 (3). Reaction of [Mo3(μ3-S)(μ2-S)(μ2-O)2(H2O)9]4+ with [Re(CO)5Cl] produces cuboidal cluster [Mo4(μ3-S)4(H2O)12]5+. [Copyright &y& Elsevier]

Abstract: The dimolybdenum complex cis-[Mo2Cp2(O)(μ-PPh2)2(CO)] (1) reacted with either [H(OEt2)2](BAr′4), (Ar′=3,5-C6H3(CF3)2), or HBF4·OEt2 to give the corresponding hydroxo derivatives [Mo2Cp2(OH)(μ-PPh2)2(CO)]+, which at room temperature rearrange to the oxohydride isomers [Mo2Cp2(μ-H)(O)(μ-PPh2)2(CO)]+ via a protonation/deprotonation sequence involving the hydride-hydroxo complex [Mo2Cp2(μ-H)(OH)(μ-PPh2)2(CO)]2+ (Cp=η5-C5H5). All these cations were characterized spectroscopically in solution, but none of them could be isolated as a solid material. The reaction of 1 with 2equiv of HBF4·OEt2 eventually led to the formation of the tetrafluoroborate complex [Mo2Cp2(κ2-F2BF2)(μ-PPh2)2(CO)](BF4) (Mo–Mo=2.841(2)Å). The BF4 − ligand in the latter complex was easily displaced by nitriles at room temperature to give the corresponding tris(nitrile) derivatives [Mo2Cp2(μ-PPh2)2(CO)(NCR)3](BF4)2 (R=Me, Ph), and by acetylacetone (acac-H), to give the acetylacetonate complex [Mo2Cp2(κ2-acac)(μ-PPh2)2(CO)](BF4) (2.831(2)Å). [Copyright &y& Elsevier]

Abstract: The reaction of [MoO2(acac)2] with hydrochloric salts of pyridoxal thiosemicarbazone ligands, H2L1–3·HCl, in dry methanol or acetonitrile resulted in the formation of the mononuclear complex [MoO2(HL1)(CH3OH)]Cl·1.5CH3OH (1a) or polynuclear complexes [{MoO2(HL1–3)}Cl] n (1–3) containing a different substituent on the nitrogen atom of the N-thioureide fragment: Ph (1 and 1a), Me (2) or H (3). New dinuclear molybdenum(V) complexes [Mo2O3(HL1–3)2]Cl2 (4–6) were obtained by oxygen atom abstraction from 1–3 with triphenylphosphine. All compounds were characterized by chemical analysis, IR spectroscopy, one- and two-dimensional NMR methods, TGA and in selected cases by DSC measurements. In addition, the crystal and molecular structure of 1a was determined by single crystal X-ray diffraction. All molybdenum(VI) species were used as (pre)catalysts for olefin epoxidation under solvent-free conditions with a 0.05% Mo loading versus olefin. [Copyright &y& Elsevier]

Abstract: Several new binuclear and polynuclear dioxomolybdenum(VI) Schiff base complexes have been synthesized. The reaction of bis(acetylacetonato)dioxomolybdenum with 5-dichlorosalicylaldehyde 4-ethylthiosemicarbazide (L1/L2) in the presence of 4,4′-bipyridine (4,4′-bpy) or 4,4′-bipyridine N,N′-dioxide (4,4′-dpdo) gave a binuclear cis-dioxomolybdenum complex [(MoO2)2L2(D-D)], in which the bidentate ligand, 4,4′-bipyridine or 4,4′-bipyridine N,N′-dioxide (D-D), formed a bridge between the two molybdenum atoms. A second type of dinuclear dioxomolybdenum(VI) Schiff base complex, [(MoO2)2L′D2], was formed by the reaction of bis(acetylacetonato)dioxomolybdenum with 1,4-bis(3-ethoxy-salicylaldehyde carbohydrazonato)butane (L′) in the presence of ethanol or hexamethylphosphoramide (D). In this case, the two molybdenum atoms are not bridged directly by a bidentate ligand, but are coordinated at each end to the O,N,O donor atoms of the symmetrical hexadentate Schiff base ligand. The syntheses of polynuclear dioxomolybdenum(VI) [(MoO2)L′(D-D)] n complexes were achieved by the reaction of the second type of dinuclear dioxomolybdenum(VI) complex, [(MoO2)2L′D2], with the bidentate ligand 4,4′-bipyridine (D-D). These complexes were characterized by elemental analysis, electronic spectra, IR, 1H and 13C NMR spectroscopies, thermogravimetric analysis and cyclic voltammetry. An X-ray study shows that each molybdenum site in the dinuclear and polynuclear complexes adopts an octahedron geometry. The dioxomolybdenum(VI) complexes show catalytic activity for the oxidation of alcohols with H2O2 as an oxidant. [Copyright &y& Elsevier]

The cycloheptatrienyl molybdenum alkynyl complex [Mo(CCH)(dppe)(η-C7H7)], 1(dppe = Ph2PCH2CH2PPh2), undergoes oxidative dimerizationon reaction with [FeCp2]PF6in thf at −78°C to give the bis(vinylidene) [{Mo(dppe)(η-C7H7)}2(μ-CCH-CHC)][PF6]2, [2][PF6]2. Deprotonation of [2][PF6]2withKOButyields butadiyndiyl-bridged [{Mo(dppe)(η-C7H7)}2(μ-CC-CC)], 3, which undergoes in situaerial oxidationto give [{Mo(dppe)(η-C7H7)}2(μ-C4)][PF6], [3]PF6, as the major product. The cyclic voltammogram of [3]PF6exhibits a series of four redox processesindicative of sequential formation of [{Mo(dppe)(η-C7H7)}2(μ-C4)]n(n= 0, 1, 2, 3, 4) with the comproportionationconstant, KC, for [3]PF6of 1.9 × 107. Spectroscopic investigationson [3]PF6by IR, Raman, NIR, and EPR spectroscopyreveal properties characteristic of a d5/d6mixedvalence complex with a localized electronic structure and an estimatedintramolecular electron transfer rate in the range 108–1010s–1. The experimental NIR spectrum of[3]PF6is consistent with the predicted spectralcharacteristics of a three-state model for bridge-mediated, electrontransfer in a weakly coupled, symmetrical mixed valence system. Thedication [3][PF6]2was isolatedby chemical oxidation and structurally characterized; magnetic susceptibilitymeasurements on [3][PF6]2in thetemperature range 2–300 K reveal strong antiferromagnetic couplingwith the exchange coupling constant Jab(defined according to the Hamiltonian Ĥspin=–Jab·Ŝa·Ŝb) determined as−406 (±3) cm–1. [ABSTRACT FROM AUTHOR]

The photochemistry of (η6-benzene)Mo(CO)3was investigated by picosecond time-resolved infrared spectroscopyin n-heptane solution at room temperature. Two excitationwavelengths, 400 and 266 nm, were used. The photophysical processesof this system depend on the excitation wavelength. Excitation with400 nm light populates predominantly a metal-to-arene charge-transferexcited state which relaxes to the ground state within 150 ps of excitation.In addition, (η6-benzene)Mo(CO)2(n-heptane) is produced in low yield within the rise timeof these experiments (500 fs). Excitation with 266 nm radiation resultsin a depletion of (η6-benzene)Mo(CO)3absorptionsbut no excited state or product νCOabsorptions areevident at short time scales (<10 ps). The CO-loss process proceedsover the subsequent 100 ps with concomitant formation of a metal-to-COcharge-transfer excited state and parent recovery. An excited-statemodel involving excited-state crossing is proposed to explain theseobservations. [ABSTRACT FROM AUTHOR]

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)2], 1--5, where Rdtc- refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1--5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C N) and v(C S) vibrations, which wavelengths decrease in the order: Pipdtc > N- -Mepzdtc > Morphdtc > Pzdtc > Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1--5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands. [ABSTRACT FROM AUTHOR]

We have studied the sequence of phase transformations of the thermolysis products of tungsten- and molybdenum-containing metalorganic compounds and examined the influence of various phases on the formation of nanocrystalline carbide materials and the possibility of controlling the particle size of forming phases. We have obtained WC and WC/Co materials ranging in crystallite size from 13 to 26 nm and high-porosity (up to 80%) molybdenum, nickel-molybdenum, and titanium-molybdenum materials ranging in strength from 5 to 26 MPa. [ABSTRACT FROM AUTHOR]

Abstract: Electrochromic organomolybdenum oxide (MoOxCy) films are deposited onto 60Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates by low temperature plasma-enhanced chemical vapor deposition (PECVD) using a precursor of molybdenum carbonyl vapor, which is carried by argon gas, mixed with oxygen gas and synthesized by radio frequency power at room temperature (23°C). The MoO x C y films with modified surface morphology and compositions of varying oxygen contents are proven to offer noteworthy electrochromic performance. Porous surface of the MoO x C y film (398nm thick) provides Li+ ion diffusion coefficient value of 1.7×10−10 cm2/s for Li+ de-intercalation at a potential scan rate of 2mV/s. High x/y value at high surface composition of oxygen to carbon in the MoO x C y film offers light modulation with transmittance variation of up to 63% and coloration efficiency of 36cm2/C at a wavelength of 800nm for 200 cycles of Li+ intercalation and de-intercalation. PECVD-synthesized MoO x C y thin films show promising electrochromic properties for applications in flexible electrochromic devices. [Copyright &y& Elsevier]

The series of molybdenum indenyl compounds [(Ind′)Mo(CO)2(NCMe)2][BF4] was prepared, and their reactivity toward spiro[2.4]hepta-4,6-diene was studied. It was observed that the spiro[2.4]hepta-4,6-diene ring opening could be blocked through substitution in the indenyl ring. Hence, the 2-substituted compound [(η5-C9H6Me)Mo(CO)2(NCMe)2][BF4] and 1,3-disubstituted compound [(η5-C9H5tBu2)Mo(CO)2(NCMe)2][BF4] do not produce the usual ansa-compounds but the compounds with η4-bonded spiro[2.4]hepta-4,6-diene [(Ind′)(η4-C5H4(CH2)2)Mo(CO)2][BF4]. The use of 1-substituted compounds [(η5-C9H6R)Mo(CO)2(NCMe)2][BF4] (R = Ph, tBu) or compounds with less sterically demanding substituents in the 1,3-positions [(η5-C9H5Ph2)Mo(CO)2(NCMe)2][BF4] does not block the ring-opening reaction. These compounds give ansa-molybdenocenes [(Ind′)(η5-C5H4CH2-η1-CH2)Mo(CO)][BF4] in a manner similar to that for the unsubstituted analogue. The reaction products were characterized by NMR and IR spectroscopy. Structures of [(η5-C9H5Ph2)Mo(η3-C3H5)(CO)2], [(η5-C9H6Ph)(η5-C5H4CH2-η1-CH2)Mo(CO)][BF4], and [(η5-C9H5Ph2)(η5-C5H4CH2-η1-CH2)Mo(CO)][BF4] were determined by single-crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

The design and study of organometallic mixed-valence complexes is complicated by the mixing of metal d and bridging ligand π orbitals, which often makes the assignment of metal oxidation states ambiguous. However, in the case of complexes based on the cycloheptatrienyl-ligated molybdenum fragment, Mo(dppe)(η-C7H7), the strong ring to metal π bonding and metal to ring δ back-bonding interactions stabilize four of the metal d orbitals, while the dz2orbital is destabilized by filled−filled interactions with the a-type MO of the C7H7ring. When the Mo(dppe)(η-C7H7) auxiliary is used in conjunction with a 1,12-bis(ethynyl)-1,12-carbaborane-based bridging ligand, a weakly coupled (Robin and Day class II) mixed-valence system, [{Mo(dppe)(η-C7H7)}2{μ-1,12-(CC)2-1,12-C2B10H10}]([2]), with well-defined molybdenum oxidation states can be prepared. The near-IR region of [2]笘扮⭬ three intervalence charge transfer (IVCT) transitions and two lower intensity interconfigurational (or dd) transitions, which have been resolved through spectral deconvolution. The band shape of the lowest energy IVCT transition associated with [2], which arises from electron exchange between the dz2-type orbitals at the two Mo centers, is in excellent agreement with the predictions of the Hush two-state model for weakly coupled mixed-valence complexes. The half-height bandwidths of the higher energy IVCT transitions, which arise from transitions between lower lying metal orbitals that have symmetry properties that permit more significant mixing with the bridging ligand, are in less good agreement with the Hush model, due to the breakdown of the two-state approximation through the greater involvement of the bridge-based orbitals in those transitions. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic activities of the complexes, Cp′M(CO)3X (Cp′=Cp (η5-C5H5), Cp* (η5-C5Me5); M=Mo, W; X=Cl, CH3) and Mo(CO)6 have been examined for the oxidation of phenol (37.6g/L) using H2O2 as oxidant in aqueous solution. Among them, CpMo(CO)3Cl and CpMo(CO)3(CH3) showed the highest catalytic activity. Conversion of phenol at 55°C is more than 80% after 24h when water is used as solvent and the ratio of catalyst:phenol:H2O2 is 1:50:200. The main oxidation products observed in solution are oxalic acid and catechol, together with trace amount of p-benzoquinone and maleic acid. Under similar conditions, binary Mo(CO)6 catalyses phenol oxidation giving hydroquinone and p-benzoquinone as main products. [ABSTRACT FROM AUTHOR]

The successive treatment of terminal alkynes, HCCR (R = C6H4Me-4, SiMe3), with nBuLi and gray selenium affords LiSeCCR, which in turn reacts with [FeCl(CO)2(η-C5H5)], [NiCl(PPh3)(η-C5H5)], and [MoI(CO)3(η-C5H5)] to afford the alkynylselenolato complexes [Fe(SeCCR)(CO)2(η-C5H5)], [Ni(SeCCR)(PPh3)(η-C5H5)], and [Mo(SeCCR)(CO)3(η-C5H5)], two examples of which have been structurally characterized. When [MoI(CO)3{HB(pz)3}] (pz = pyrazol-1-yl) was however employed as the electrophile, low yields of the selenoketenyl complex [Mo(η2-C,C′-SeCCR)(CO)2{HB(pz)3}] were obtained via the presumed intermediacy of the alkynylselenolato complex [Mo(σ-SeCCR)(CO)3{HB(pz)3}], which is perhaps destabilized relative to the selenoketenyl complex by the octahedral enforcer character of the HB(pz)3ligand. [ABSTRACT FROM AUTHOR]

Abstract: A new reduced zincic molybdophosphate, (H2bpp)3[Zn3Mo12 VO24(OH)6(H2O)2(HPO4)6(PO4)2]·2H2O 1 (bpp=1,3-bis(4-pyridyl)propane) has been hydrothermally synthesized and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. Compound 1 crystallizes in the tetragonal space group I 41/a c d with a=31.8033(4) Å, b=31.8033(4) Å, c=34.5593(8) Å, V=34955.0(10) Å3, and Z=16 and exhibits a 4,6-connected 3-D framework with (32.84)(34.42.83.95.10) topology. The basic building blocks of [Zn(2)(Mo6P4)2] are linked through [Zn(3)O6] octahedra and [Zn(1)O4] tetrahedra to construct 1-D chains along four different directions. Such 1-D chains are further connected by [Zn(1)O4]2+ linkers to form a 3-D intricate framework with helical channels occupied by protonated bpp and water molecules. Additionally, the electrochemical property of the 1-CPE has been studied in detail. [ABSTRACT FROM AUTHOR]

Refluxing toluene solutions of [Mo(η3-allyl)(O2CMe)(CO)2(pz*H)2] (pz*H = pzH, pyrazole, or dmpzH, 3,5-dimethylpyrazole) without exclusion of air, give the tetranuclear complexes [Mo2O2(O2CCH3)2{(μ3-O)(μ-pz*)Mo(η3-allyl)(CO)2(pz*H)}2], where two chelating acetato ligands and two “Mo(η3-allyl)(CO)2(pz*H)(μ-pz*)” fragments are bonded to a central Mo2O42+moiety. [ABSTRACT FROM AUTHOR]