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1,2,3,4,5-pentathiepines (PTEs) are naturally occurring polysulfides of increasing scientific interest based on their identified pharmacological activities. Artificial PTEs with N-heterocyclic backbones are efficiently synthesized via mediation by a molybdenum–oxo-bistetrasulfido complex. A common feature of all precursor alkynes successfully used to date in this reaction is the presence of a –CH(OEt)2 group since the previously postulated mechanism requires the presence of one OEt– as the leaving group, and the second must become a transient ethoxonium moiety. This raised the question of whether there really is a need for two, maybe only one, or possibly even zero ethoxy substituents. This research problem was systematically addressed by respective variations in the precursor-alkyne derivatives and by employing one related allene species. It was found that the total absence of ethoxy substituents prevents the formation of PTEs entirely, while the presence of a single ethoxy group results in the possibility to distinctly functionalize the position on the resulting N-heterocyclic pyrrole five ring in the target compound. This position was previously exclusively occupied by an –OEt for all products of the molybdenum-mediated reaction. The allene was applied with similar success as precursor as with the related alkyne. The now-employable significant change in precursor composition gives access to a whole new PTE subfamily, allowing further modulation of (physico)-chemical properties such as solubility, and provides additional insight into the mechanism of PTE formation; it comprises a merely partial validation of the previous hypothesis. The new alkyne precursors and pentathiepines were characterized by a variety of instrumental analyses (NMR, mass spec, UV–vis) and in six cases (one alkyne precursor, one unexpected side product, and four PTEs) by single-crystal X-ray diffraction. Syntheses, isolation procedures, analytical data, and the impact of the findings on the previously proposed mechanism are described in detail herein. [ABSTRACT FROM AUTHOR]

Molybdenum carbides (MoxC) with multiple crystal structures are a group of promising catalysts for low-temperature CO2 reduction to CO. However, the relationship between the C and Mo exposure and the activity is elusive, since control of the C and Mo exposure under the same crystal structures is a difficult task. Herein, the C and Mo exposure at the surface of α-MoC1−x was successfully modulated by control of the S-doped amount in the precursors. It is found that the C exposure was gradually increased with the S doping amount decreasing, and that sole Mo or C exposure will go against CO2 and H2 activation, since bent adsorbed CO2 and H2 dissociation require the synergy of surface C and Mo. In other words, MoC1−x with moderate exposure ratios of C to Mo is most favorable. As a result, the MoC/SiO2-390 catalyst, whose precursor was obtained by annealing molybdenum sulfide at 390 ℃ in air, has the optimal activity, exhibiting a 1001 μmol gcat−1 h−1 of the CO yield with ~89% selectivity at 150 ℃ under ambient pressure. Additionally, CO2 reduction to CO over α-MoC1−x proceeds mainly through the formate (HCOO*) pathway under current operating condition. The present work supplied further insight into the influence of α-MoC1−x surface structures on CO2 reduction. The moderate exposure ratios of C to Mo at the surface of α-MoC1−x is the most favorable for CO2 reduction to CO, since bent adsorbed CO2 and H2 dissociation require the synergy of surface C and Mo. [ABSTRACT FROM AUTHOR]

New methylsulfate complex (Bu4N)2[Мо6I8(O3SOCH3)6] (I) is synthesized by the reaction of (Bu4N)2[Mo6I8(C≡C–C(O)OCH3)6] with dimethyl sulfate (CH3)2SO4. According to the XRD data, the molybdenum atoms are coordinated by the monodentate methylsulfate ligands. In a DMSO solution, the complex undergoes solvolysis accompanied by the complete substitution of the methylsulfate ligands by the solvent molecules. A powder sample of cluster I luminesces (phosphorescence) with the emission maximum at a wavelength of 620 nm (77 K). Increasing temperature to 300 K results in the shift of the emission maximum to 650 nm and a decrease in the integral intensity by 1.6 times. [ABSTRACT FROM AUTHOR]

Three new trinuclear complexes containing either nickel(II), copper(II) or zinc(II), [Ni3L2(NO3)2(CH3OH)2]·2CH3OH (1), [Cu3Br2L2] (2), [Zn3L2(NCS)2(CH3OH)2]·0.5CH3OH·0.5H2O (3), and a new dioxidomolybdenum(VI) complex, [MoO2L] (4), have been prepared from the bis-Schiff base N,N'-bis(4-bromosalicylidene)-1,3-propanediamine (H2L) with various metal salts in methanol. The complexes were characterized by elemental analysis, IR and UV–Vis spectra. Molecular structures were confirmed by single crystal X-ray diffraction experiments. The Ni ions in 1 adopt an octahedral coordination environment, bridged by phenolate oxygen and nitrate ligands. The Cu ions in 2 are square pyramidal and square planar, and the Zn ions in 3 are square pyramidal and octahedral. The metal atoms in 2 and 3 are bridged by phenolate oxygen donors. The Mo ion in 4 is octahedral. The Schiff base ligand coordinates to the metal atoms through two phenolate O and two imino N donors. Biological assays revealed that the nickel and copper complexes have effective urease inhibition. [ABSTRACT FROM AUTHOR]

Among the major challenges facing the hydrogen economy is the issue of hydrogen storage. In terms of "future energy needs", electrochemical hydrogen storage in solid-state materials is an accepted perspective that could mitigate the discontinuation of primary energy sources. In this study, we demonstrate the electrochemical properties of a complex metal oxide that contains the molybdate group, Dy 2 Mo 3 O 12. Wet-chemical synthesis of nanostructured Dy 2 Mo 3 O 12 is primarily carried out using ultrasound-assisted wet-chemical methods in the presence of a variety of surfactants. The structural and morphological observations of the samples confirm a pure and highly crystalline structure obtained in the presence of CTAB surfactant at 900 °C and 30 min of sonication, with an average crystalline size of 29 nm. Based on the FTIR spectrum of this sample, it can be concluded that there are significant absorptions indicating the formation of oxygen-metal bonds. The specific surface area and pore volume of the selected sample are 4.543 m2/g and 0.0284 cm3/g, respectively, demonstrating its porous structure. Electrochemical studies of this sample at various temperatures have revealed an enhanced discharge capacity (5100 mAh/g at 65 °C) with a capacity retention rate of 97%. Based on these findings, mixed metal oxides containing at least one active charge transfer species (Red./Ox.) are suitable for use in solid-state hydrogen storage devices. [Display omitted] • Pioneering technique for creating Dy 2 Mo 3 O 12 -Dy 2 O 3 nanocomposites. • Showcasing a unique material that holds potential for enhanced electrochemical hydrogen storage. • Significant strides in achieving enhanced electrochemical hydrogen storage. • Foundational step in the exploration of materials designed for harvesting hydrogen storage systems. [ABSTRACT FROM AUTHOR]

The reaction of molybdenum complexes with a tris(pyrazolyl)borate ligand (Et4N[TpMo(CO)3] and Et4N[Tp*Mo(CO)3] (Tp = hydridotris(pyrazolyl)borate, Tp* = hydridotris(3,5-dimethylpyrazolyl)borate)) and InBr3 at a 1:1 molar ratio afforded molybdenum–indane complexes (Et4N[TpMo(CO)3(InBr3)] 1 and Et4N[Tp*Mo(CO)3(InBr3)] 2). In addition, tungsten–indane complexes, Et4N[TpW(CO)3(InBr3)] 3 and Et4N[Tp*W(CO)3(InBr3)] 4, were obtained by the reaction of corresponding tungsten complexes. Complex 4 reacted with H2O to form the hydrido complex Tp*W(CO)3H, in which the W–In bond was cleaved. On the other hand, 4 reacted with three equiv. of AgNO3 to form Et4N[Tp*W(CO)3{In(ONO2)}] 5, in which three substituents on the In were exchanged while retaining the W–In dative bond. Complexes 1–5 were fully characterized using NMR measurements and elemental analyses, and the structures of 1–5 and Et4N[Tp*W(CO)3] were determined via X-ray crystallography. These are the first examples of mononuclear molybdenum– and tungsten–indane complexes with Mo–In and W–In dative bonds. [ABSTRACT FROM AUTHOR]

The ligand environment of the cluster complex is modified by a reaction of the cluster with Br2 in N,N-dimethylformamide at room temperature, which results in bromination of all pyrazole and pyrazolate ligands at the fourth position and in bromide ligand substitution for apical pyrazole. The solvent effect on ligand bromination is considered. The cluster complex crystallizes in the tetragonal symmetry (space group P4/n) and forms infinite layers via hydrogen bonds between the terminal 4-bromopyrazole ligands and the bromine anion. The complex also demonstrates reversible one-electron reductions of the cluster core shifted relative to the initial compound by 30 mV and 90 mV towards larger potentials. [ABSTRACT FROM AUTHOR]

The ligand environment of the cluster complex is modified by a reaction of the cluster with Br2 in N,N-dimethylformamide at room temperature, which results in bromination of all pyrazole and pyrazolate ligands at the fourth position and in bromide ligand substitution for apical pyrazole. The solvent effect on ligand bromination is considered. The cluster complex crystallizes in the tetragonal symmetry (space group P4/n) and forms infinite layers via hydrogen bonds between the terminal 4-bromopyrazole ligands and the bromine anion. The complex also demonstrates reversible one-electron reductions of the cluster core shifted relative to the initial compound by 30 mV and 90 mV towards larger potentials. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae , a facultative anaerobe, relies on acquiring molybdenum to sustain growth in anaerobic conditions, a crucial factor for the pathogen to establish infections within host environments. Molybdenum plays a critical role in pathogenesis as it forms an essential component of cofactors for molybdoenzymes. K. pneumoniae utilizes the ABC (ATP-Binding-Cassette) transporter encoded by the modABC operon for uptake of the group VI elements molybdenum and tungsten. In this study, we determined the X-ray crystal structures of both the molybdenum-free and molybdenum-bound substrate-binding protein (SBP) ModA from Klebsiella pneumoniae to 2.00 Å and 1.77 Å resolution respectively. ModA crystallizes in the space group P222 with a single monomer in one asymmetric unit. The purified protein remained soluble and specifically bound molybdate and tungstate with K d values of 6.3 nM and 5.2 nM, respectively. Tungstate competes with molybdate by binding to ModA, resulting in enhanced antimicrobial activity. These data provide a starting point for structural and functional analyses of molybdate transport in K. pneumoniae. • We determined the 2.0 Å crystal structure of K. pneumoniae ModA. • A molybdate-bound structure reveals the residues required for binding molybdenum. • Molybdate and tungstate bind with similarly high affinity to ModA. • ModA is a potential target for therapeutic intervention using tungstate. [ABSTRACT FROM AUTHOR]

The compounds Li6MoN4 and Li6WN4 were prepared from the reactants M (M = Mo, W) and Li3N in a radiofrequency furnace at 1000 °C. The lithonitridometallates crystallize in the tetragonal system with the lattice parameters: a = 6.6844(1), c = 4.9294(1) Å for Li6WN4 based on single-crystal X-ray diffraction data and a = 6.6611(3), c = 4.9338(3) Å for Li6MoN4 taken from powder X-ray diffraction data. Colorless to slightly reddish single-crystals of the tungsten compound were isolated and the crystal structure was refined in the space group P42/nmc (no. 137) with Z = 2 and the powder X-ray data of the molybdenum compound were analyzed by a Rietveld refinement. Both structures belong to the Li6[ZnO4] type published by Hoppe et al. in 1987 (Untenecker H., Hoppe R. Z. Anorg. Allg. Chem. 1987, 551, 147–150) and could be doped with Ce3+ for the first time. The investigated compounds show a reddish color impression upon UV to blue irradiation and exhibit a broad emission band with a maximum at λmax = 693 nm (fwhm 97 nm) for Li6MoN4 and at λmax = 653 nm (fwhm 133 nm) for Li6WN4. [ABSTRACT FROM AUTHOR]

A new compound, K5[(Mo3.2W1.8)O11](PO4)3[(P0.5Mo0.5)O4], was synthesized via solid-state reaction and its crystal structure was determined by single-crystal X-ray diffraction. This compound crystallizes in the space group Pnma, with a = 9.0360(4) Å, b = 10.1603(4) Å, c = 26.1538(12) Å and V = 2401.14(18) Å3. The structure consists of a corner-sharing MO6–TO4 (M = Mo, W; T = P, Mo) polyhedral connection arranged to form an ordered packing of ∼14.9 Å-thick layers parallel to (001). The stacking of the layers forms trigonal, tetragonal and hexagonal channels. XPS study reveals the presence of W at the hexavalent state only, whereas Mo appears as a mixed-valent species (Mo6+, Mo5+ and Mo4+). Magnetic susceptibility reveals the occurrence of a relevant antiferromagnetic coupling and is consistent with the presence of reduced metal species as indicated by the XPS results. [ABSTRACT FROM AUTHOR]

Rare-earth sodium- and fluorine-substituted molybdates with the Na0.65La4.35Mo3O15.81±δF0.07±ε composition were synthesized for the first time as single crystals. An accurate X-ray diffraction analysis of three samples at room temperature showed that the obtained crystals are isostructural to undoped cubic compounds of the Ln5Mo3O16+δ family (space group Pn 3 ¯ n). Sodium cations partially occupy one of the two lanthanum positions and center the more distorted LaO8 polyhedra, while fluorine anions occupy over-stoichiometric oxygen positions in the vast interstices (cavities) of the structure. The partial substitution of fluorine atoms for oxygen ones affects the transport characteristics of compounds by activating the oxygen atoms in the anionic subsystem due to the effect of supplementary electrostatic repulsion between anions of different types. [ABSTRACT FROM AUTHOR]

A series of new cluster compounds with {Re4Mo2S8} and {Re3Mo3S8} cores has been obtained and investigated. The clusters with different Re/Mo ratios were isolated as individual compounds, which made it possible to study their spectroscopic and electrochemical properties. The geometry of the new clusters was studied using a combination of X-ray diffraction analysis, XAS and quantum chemical DFT calculations. It was shown that the properties of the new clusters, such as the number and position of electrochemical transitions, electronic structure and change in geometry with a change in charge, are similar to the properties of clusters based on the {Re4Mo2Se8} and {Re3Mo3Se8} cores described earlier. [ABSTRACT FROM AUTHOR]

Arsenic contamination of groundwater is among one of the biggest health threats affecting millions of people in the world. There is an urgent need for efficient arsenic biosensors where the use of arsenic metabolizing enzymes can be explored. In this work, we have solved four crystal structures of arsenite oxidase (Aio) in complex with arsenic and antimony oxyanions and the structures determined correspond to intermediate states of the enzymatic mechanism. These structural data were complemented with density-functional theory calculations providing a unique view of the molybdenum active site at different time points that, together with mutagenesis data, enabled to clarify the enzymatic mechanism and the molecular determinants for the oxidation of As(III) to the less toxic As(V) species. [ABSTRACT FROM AUTHOR]

Rare-earth fluorine-containing molybdates of the Ln5Mo3O16+δ oxygen–electron conductor family with the LiLa4Mo3O15F composition were synthesized for the first time as single crystals by the flux method. An accurate X-ray diffraction analysis of the obtained crystals was carried out at 20 and −183 °C. The LiLa4Mo3O15F compound is isostructural to the fluorine-free analogue with a cubic structure (space group Pn 3 ¯ n). It is shown that lithium atoms replace one of the two positions of lanthanum in the more distorted LaO8 polyhedron. According to X-ray diffraction analysis, fluorine atoms replace the positions of over-stoichiometric oxygen located in the vast cavities of the structure. So, fluorine anions can promote the interstitial conductivity of F-containing LiLa4Mo3O15F molybdates. [ABSTRACT FROM AUTHOR]

Quadruple-bond dimolybdenum complexes provide invaluable insight into the two-electron bond, with structural chemistry providing a foundation for examination of bond properties. The synthesis and solid-state structure of the quadruple-bonded dimolybdenum(II) complex tetrakis(μ-4-methylbenzoato-κ2O:O′)bis[(tetrahydrofuran-κO)molybdenum(II)] tetrahydrofuran disolvate, [Mo2(C8H7O2)4(C4H8O)2]·2C4H8O, are presented. This complex crystallizes in a triclinic cell with low-symmetry space group P\overline{1}. The dimolybdenum paddlewheel structure comprises four methylbenzoate ligands and two axial THF ligands. The dimolybdenum bond distance of 2.1012 (4) Å is exemplary of this class of compounds.

The reaction of molybdenum complexes with a tris(pyrazolyl)borate ligand (Et4N[TpMo(CO)3] and Et4N[Tp*Mo(CO)3] (Tp = hydridotris(pyrazolyl)borate, Tp* = hydridotris(3,5-dimethylpyrazolyl)borate)) and InBr3 at a 1:1 molar ratio afforded molybdenum–indane complexes (Et4N[TpMo(CO)3(InBr3)] 1 and Et4N[Tp*Mo(CO)3(InBr3)] 2). In addition, tungsten–indane complexes, Et4N[TpW(CO)3(InBr3)] 3 and Et4N[Tp*W(CO)3(InBr3)] 4, were obtained by the reaction of corresponding tungsten complexes. Complex 4 reacted with H2O to form the hydrido complex Tp*W(CO)3H, in which the W–In bond was cleaved. On the other hand, 4 reacted with three equiv. of AgNO3 to form Et4N[Tp*W(CO)3{In(ONO2)}] 5, in which three substituents on the In were exchanged while retaining the W–In dative bond. Complexes 1–5 were fully characterized using NMR measurements and elemental analyses, and the structures of 1–5 and Et4N[Tp*W(CO)3] were determined via X-ray crystallography. These are the first examples of mononuclear molybdenum– and tungsten–indane complexes with Mo–In and W–In dative bonds.

Host–guest assemblies open up opportunities for developing novel functional CLUSPOM multicomponent systems based on transition metal clusters (CLUS), polyoxometalates (POMs) and macrocyclic organic ligands. In water–ethanol solution γ-cyclodextrin (γ-CD) interacts with halide metal clusters [M6Cl14]2– (M = Mo, W) to form sandwich-type structures. The supramolecular association between the clusters and CDs, however, remains weak in solution, and the interactions are not strong enough to prevent the hydrolysis of the inorganic guest. Although analysis of the resulting crystal structures reveals inclusion complexation, 1H NMR experiments in solution show no specific affinity between the two components. The luminescent properties of the host–guest compounds in comparison with the initial cluster complexes are also studied to evaluate the influence of CD. [ABSTRACT FROM AUTHOR]

Quadruple-bond dimolybdenum complexes provide invaluable insight into the two-electron bond, with structural chemistry providing a foundation for examination of bond properties. The synthesis and solid-state structure of the quadruple-bonded dimolybdenum(II) complex tetra­kis­(μ-4-methyl­benzoato-κ²O:O′)bis[(tetra­hydro­furan-κO)molybdenum(II)] tetra­hydro­furan disolvate, [Mo2(C8H7O2)4(C4H8O)2]·2C4H8O, are presented. This complex crystallizes in a triclinic cell with low-symmetry space group P[\overline{1}]. The dimolybdenum paddlewheel structure comprises four methyl­benzoate ligands and two axial THF ligands. The dimolybdenum bond distance of 2.1012 (4) Å is exemplary of this class of compounds. [ABSTRACT FROM AUTHOR]

A novel high-pressure molybdenum nitride phase, Mo3N5, was synthesized at above 45 GPa via a nitridation reaction of molybdenum with nitrogen under high pressure using a laser-heated diamond anvil cell. Mo3N5, having an N–N dimer and 7-coordinated Mo sites, crystallizes in an orthorhombic structure with a space group of Cmcm (No. 63) without other prototype structures. The refined lattice parameters for Mo3N5 were a = 2.86201(2) Å, b = 7.07401(6) Å, and c = 14.59687(13) Å. The DFT enthalpy calculation suggested that Mo3N5 is a high-pressure stable phase, which is also consistent with an increasing coordination number compared to ambient- and low-pressure phases. The zero-pressure bulk modulus of Mo3N5 was determined to be K0 = 328(4) GPa with K′0 = 10.1(6) by the fitting for the compression curve, which is almost consistent with the theoretical E–V curve and elastic stiffness constants. The compressibility of Mo3N5 has axial anisotropy corresponding to the N–N dimer direction in the crystal structure. [ABSTRACT FROM AUTHOR]

Silanones (O＝SiR2) are highly reactive species that readily convert to oligomeric siloxane (O–SiR2)n. The coordination of silanones to transition metal fragments to afford silanone-coordinated complexes is a reliable silanone stabilization method. Herein, a pyridine-stabilized silanone molybdenum complex Cp*(OC)2Mo{O＝SiMes2(py)}(SiMe3) (2b, Cp*: η5-C5Me5, Mes: 2,4,6-Me3C6H2, and py: pyridine) was synthesized by reacting the silyl(silylene) complex Cp*(OC)2Mo(＝SiMes2)(SiMe3) (4b) with pyridine-N-oxide in pyridine. X-ray crystal structure analysis revealed that the geometry of complex 2b is similar to those of the previously synthesized DMAP-stabilized analogue Cp*(OC)2Mo{O＝SiMes2(DMAP)}(SiMe3) (2a, DMAP: 4-(dimethylamino)pyridine). The Si＝O and Mo–O bond distances in 2b are similar to those observed in 2a, but the N–Si coordination bond of 2b is slightly longer (approximately 0.05 Å) than that of 2a, indicating weaker pyridine coordination than that of DMAP. The reaction of 2a with excess PMe3 in C6D6 at room temperature for 28 h afforded Cp*(OC)2Mo(PMe3)(SiMe3) (5c) in a 43% NMR yield. In contrast, reacting 2b with excess PMe3 in C6D6 at room temperature for 9 h afforded 5c and the five-membered metallacyclic carbene complex Cp*(OC)Mo(＝C(SiMe3)OSiMes2O)(PMe3) (6) in 10% and 41% NMR yields, respectively. The reactions of pyridine-stabilized silanone complexes Cp*(OC)2M(O＝SiMes2(py))(SiMe3) (M = Mo (2b) and W (1b)) with acetone proceeded via pyridine elimination, coordination of acetone to the Si center in the silanone ligand, and elimination of HSiMe3 to give Cp*(OC)2M{OSiMes2OC(Me)＝CH2} (M = Mo (8) and W (9)) in high yields. [ABSTRACT FROM AUTHOR]

This study investigates the influence of chromium and molybdenum content (Cr: 20–35 wt%; Mo: 5 and 10 wt%) in a cobalt–chromium–molybdenum alloy system on the phases present in the microstructure, the nanomechanical, and electrochemical behavior of the alloys. A linear increase in the hardness is found in relation to the increasing chromium content for both 5 and 10 wt% Mo contents, whereas reduced modulus demonstrates an inflection at 30 wt% Cr, which is influenced by the molybdenum content. The open‐circuit potential, polarization resistivity, and linear sweep voltammetry disclose that passivity of Co–Cr–Mo alloys improves in line with increasing Cr until 30 wt%, with any further increase causing a depreciation in the corrosion properties. X‐Ray diffraction and optical metallographic analysis confirm that as the chromium content transitions through the 25–30 wt% range, the sigma (σ) phase begins to develop within the combined matrix of hexagonal close pack martensite (ε) and face‐centered cubic austenite (γ) phase. [ABSTRACT FROM AUTHOR]

Nickolayite, FeMoP, is a new terrestrial phosphide structurally related to allabogdanite (high-pressure modification of (Fe,Ni)2P), and the meteoritic phosphides florenskyite, FeTiP and andreyivanovite, FeCrP. From the point of view of chemical composition, nickolayite is an Fe-analogue of monipite, MoNiP. The mineral was discovered in the Daba-Siwaqa complex, Central Jordan, a part of the pyrometamorphic Hatrurim Formation (the Mottled Zone), whose outcrops encompass a 150 × 200 km area around the Dead Sea in the Middle East. Nickolayite appears as an accessory phase in the fused clinopyroxene–plagioclase rocks texturally resembling gabbro–dolerite. The irregularly shaped grains of the mineral, up to 80 μm in size are associated with baryte, tridymite, chromite, hematite, pyrrhotite, fluorapatite, titanite and powellite. Macroscopically, nickolayite grains possess light-grey to greyish-white colour and metallic lustre. The mineral is ductile. The mean VHN hardness (50 g load) is 538 kg mm–2. The calculated density based on the empirical formula and the unit-cell parameters is 7.819 g cm–1. In reflected light, nickolayite has a white colour, with no bireflectance or pleochroism. The COM approved reflectance values [Rmax/Rmin (%), λ(nm)] are: 48.5/46.5 (470), 50.5/48.5 (546), 51.8/49.9 (589) and 53.9/52.0 (650). The chemical composition of the holotype crystal is (electron microprobe, average of 4 analyses, wt.%): Fe 32.21, Mo 47.06, Ni 3.69, Co 0.13, P 17.45, total 100.54, that corresponds to the empirical formula Fe1.00(Mo0.87Ni0.11Fe0.02)Σ1.00P1.00 and an ideal formula of FeMoP. Nickolayite is orthorhombic, space group Pnma, unit-cell parameters of holotype material are: a = 5.9519(5), b = 3.7070(3), c = 6.8465(6) Å, V = 151.06(2) Å3 and Z = 4. The crystal structure of holotype material was solved and refined to R1 = 0.0174 based on 251 unique observed reflections. The origin of the mineral is probably connected to the processes of co-reduction of molybdenum- and phosphorus-bearing minerals during high-temperature pyrometamorphic processes. [ABSTRACT FROM AUTHOR]

Despite that the chemistry of octahedral cluster complexes has been actively developed recently, there are still a lot of unexplored areas. For example, to date, only a few halide M6-clusters with N-heterocycles are known. Here, we obtained an apically heteroleptic octahedral iodide molybdenum cluster complex with pyridine ligands—trans-[{Mo6I8}(py)2I4] by the direct substitution of iodide apical ligands of [{Mo6I8}I6]2– in a pyridine solution. The compound co-crystalized with a monosubstituted form [{Mo6I8}(py)I5]– in the ratio of 1:4, and thus, can be described by the formula (pyH)0.2[{Mo6I8}(py)1.8I4.2]·1.8py. The composition was studied using XRPD, elemental analyses, and 1H-NMR and IR spectroscopies. According to the absorption and luminescence data, the partial substitution of apical ligands weakly affects optical properties. [ABSTRACT FROM AUTHOR]

Two cis-dioxomolybdenum complexes based on salan ligands with different backbones are reported. The first complex, dioxido{2,2′-[l,2-phenylenebis(iminomethylene)]bis(phenolato)}molybdenum(VI) dimethylformamide disolvate, [Mo(C20H18N2O2)O2]·2C3H7NO (PhLMoO2, 1b), features a phenyl backbone, while the second complex, (6,6′-{[(cyclohexane-1,2-diyl)bis(azanediyl)]bis(methylene)}bis(2,4-di-tert-butylphenolato))dioxidomolybdenum(VI) methanol disolvate, [Mo(C36H56N2O2)O2]·2CH3OH (CyLMoO2, 2b), is based on a cyclohexyl backbone. These complexes crystallized as solvated species, 1b·2DMF and 2b·2MeOH. The salan ligands PhLH2 (1a) and CyLH2 (2a) coordinate to the molybdenum center in these complexes 1b and 2b in a κ2N,κ2O fashion, forming a distorted octahedral geometry. The Mo—N and Mo—O distances are 2.3475 (16) and 1.9567 (16) Å, respectively, in 1b while the corresponding measurements are Mo—N = 2.3412 (12) Å, and Mo—O = 1.9428 (10) Å for 2b. A key geometrical feature is that the N—Mo—N angle of 72.40 (4)° in CyLMoO2 is slightly less than that of the PhLMoO2 angle of 75.18 (6)°, which is attributed to the flexibility of the cyclohexane ring between the nitrogen as compared to the rigid phenyl ring in the PhLMoO2.

The study of quadruple bonds between transition metals, in particular those of dimolybdenum, has revealed much about the two-electron bond. The solid-state structure of the quadruple-bonded dimolybdenum(II) complex tetrakis[μ-4-(trifluoromethyl)benzoato-κ2O:O′]bis[(tetrahydrofuran-κO)molybdenum(II)] 0.762-pentane 0.238-tetrahydrofuran solvate, [Mo2(p-O2CC6H4CF3)4·2THF]·0.762C5H12·0.238C4H8O or [Mo2(C8H4F3O2)4(C4H8O)2]·0.762C5H12·0.238C4H8O is reported. The complex crystallizes within a triclinic cell and low symmetry (P\overline{1}) results from the intercalated pentane/THF solvent molecules. The paddlewheel structure at 100 K has inversion symmetry and comprises four bridging carboxylate ligands encases the Mo2(II,II) core that is characterized by two axially coordinated THF molecules and an Mo—Mo distance of 2.1098 (7) Å.

The crystal structure of the [Pt(NH3)4]3Mo7O24·5.5H2O complex salt is determined for the first time by XRD. Thermal decomposition of this complex in reducing and inert atmospheres is studied. Intermediate and final products of thermal decomposition are determined. It is established that thermolysis in a reducing atmosphere leads to the formation of an ordered solid solution with the intermetallic Mo2Pt3 structure, while the final product of thermolysis in an inert atmosphere is a two-phase mixture of metallic platinum and molybdenum(IV) oxide. [ABSTRACT FROM AUTHOR]

The synthesis and single X-ray crystal structures of Tl2[W(CN)6(bpy)]·H2O, Tl[W(CN)6(bpy)], Tl57[{Fe(CN)6}12{NO3}9]·9H2O, Tl4[W(CN)8] and Tl4[Mo(CN)8] are described. Salts crystalize in the monoclinic or trigonal (Fe) space group. For all complexes, the very unusual "side-on" coordination of Tl to C and N of cyanido ligands is observed and compared to potassium cations. The very strong bonding to cyanido ligands with an 8–13 coordination number of thallium is described and discussed. The difference between potassium and thallium bonding is an indication of the biological activity of thallium and the role of Prussian blue in the thallium detoxification procedure. [ABSTRACT FROM AUTHOR]

The hybridized lanthanide‐containing molybdenum blue (Ln‐MB) wheel Na4[Mo2O2(OH)4(C6H4NO2)2]2[Mo120Ce6O366H12(OH)2(H2O)76]∼200H2O ({Mo2(C6H4NO2)2}2{Mo120Ce6}) was assembled in an aqueous one‐pot synthesis. The Ln‐MB was hybridized with 2‐picolinic acid through the generation of the organometallic counter‐ion [Mo2O2(OH)4(C6H4NO2)2]2+. Control experiments demonstrated that the position of the carboxylic acid group (2‐position to the N atom) in the hybridization component is critical in yielding single crystals of Ln‐MB. In addition to single‐crystal X‐ray diffraction (XRD) analysis, which revealed a 'Japanese rice‐ball'‐shaped Ln‐MB as the anion, elemental analyses, IR spectroscopy, and thermogravimetric analysis (TGA) were performed to confirm its structure and composition. Bond‐valence‐sum calculations (BVS) revealed that {Mo2(C6H4NO2)2}2{Mo120Ce6} is composed of a 24‐electron reduced anionic ring, which was confirmed by Vis–NIR spectroscopy. [ABSTRACT FROM AUTHOR]

The synthesis and structural determination of two isomers of the molybdenum(II) complex (η2‐but‐2‐yne)carbonylbis[2‐(4,4‐dimethyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl)benzenethiolato‐κ2N,S]molybdenum(II), [Mo(C11H12NOS)2(C4H6)(CO)] or Mo(CO)(C2Me2)(S‐Phoz)2, are presented. The N,N‐cis–S,S‐trans isomer 1 shows quite different bond lengths to the metal atom [Mo—N = 2.4715 (10) versus 2.3404 (11) Å; Mo—S = 2.4673 (3) versus 2.3665 (3) Å]. In the N,N‐trans–S,S‐cis isomer 2, which is isotypic with the corresponding W complex, the Mo—N bond lengths [2.236 (2) and 2.203 (2) Å], as well as the Mo—S bond lengths [2.5254 (8) and 2.5297 (8) Å], are almost the same. [ABSTRACT FROM AUTHOR]

The title compound, tricarbonyltris(dimethyl sulfoxide)molybdenum, [Mo(C2H6OS)3(CO)3] or fac-[Mo(CO)3(DMSO)3], crystallizes in the triclinic space group P\overline{1} with two molecules in the unit cell. The geometry around the central molybdenum is slightly distorted octahedral and the facial isomer is found exclusively. The packing within the crystal is stabilized by three-dimensional non-classical intermolecular hydrogen-bonding contacts between individual methyl substituents of dimethyl sulfoxide and the oxygen atoms of either another dimethyl sulfoxide or a carbonyl ligand on adjacent complex molecules. The observed bond lengths in the carbonyl ligands and between carbonyl carbon atoms and molybdenum are correlated to the observed FT–IR bands for the carbonyl stretches and compared to respective metrical parameters of related complexes.

• It reports the first octamolybdate porphyrin. • It has a 3D framework formed by the π-π stacking and hydrogen bonding interactions. • It can emit red photoluminescence and the CT is 7978 K. • It has CIE coordinates of (0.7236, 0.2764) and E 1/2 is 0.78 V. A novel molybdenum polyoxometalate (POM) porphyrinic compound, i.e. (Mo 8 O 26)(5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)·2H 2 O (1) was synthesized via a hydrothermal reaction of MoCl 5 , 5,10,15,20-tetra-3-pyridinyl-21H,23H-porphine and distilled water. This is the first octamolybdate porphyrinic compound. Its crystal structure and properties have been unlocked thoroughly by virtue of single-crystal X-ray diffraction, PXRD (powder X-ray diffraction), UV/vis, FTIR, photoluminescence, CIE (Commission Internationale de I'Éclairage), CT (color temperature) and cyclic voltammetric (CV) spectral analyses. The crystal structure of this compound is characteristic of an isolated (0D) motif and it is comprised of a (Mo 8 O 26)4− anion, a (5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)4+ cation and two lattice water molecues. A three-dimensional (3D) framework is formed by the π-π stacking and hydrogen bonding interactions. The solid state photoluminescence measurements show that compound 1 emits red photoluminescence which results from the (5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)4+ cations. Compound 1 has CIE chromaticity coordinates of (0.7236, 0.2764). The CT is 7978 K. The slow sweep CV of 1 exhibits a reversible wave with E 1/2 being of 0.78 V. [Display omitted] A novel molybdenum polyoxometalate (POM) porphyrinic compound was reported. It is the first octamolybdate porphyrinic compound. It features a 3D framework that is formed by the π-π stacking and hydrogen bonding interactions. The compound emits red photoluminescence which results from the (5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)4+ cations. It has CIE chromaticity coordinates of (0.7236, 0.2764) and the CT is 7978 K. The slow sweep CV exhibits a reversible wave with E 1/2 being of 0.78 V. [ABSTRACT FROM AUTHOR]

[Display omitted] • New cis -dioxo Mo(VI) complexes incorporating ONO donor Schiff base ligands derived from dihalosalicylaldehyde and nicotinic hydrazide were synthesized and characterized. • X-ray crystallographic study has confirmed the structures of the H 2 Cl 2 SN ligand and two Mo(VI) complexes (2 & 3). • All complexes were successfully screened as catalysts for the selective oxidation of benzylic alcohols employing ethanol and hydrogen peroxide. Three ONO donor Schiff base ligands were obtained by the condensation of 3,5-dihalosalicylaldehydes with nicotinoylhydrazide (H 2 Cl 2 SN: (E)-N'-(3,5-dichlorosalicylaldehyde) nicotinoylhydrazone, H 2 Br 2 SN: (E)-N'-(3,5-dibromosalicylaldehyde) nicotinoylhydrazone, and H 2 I 2 SN: (E)-N'-(3,5-diiodosalicylaldehyde) nicotinoylhydrazone on refluxing in ethanol. The treatment of [MoO 2 (acac) 2 ] (acac = acetylacetonato) with these ligands in methanol afforded cis -dioxidomolybdenum(VI) complexes [MoO 2 (Cl 2 SN)(CH 3 OH)] (1), [MoO 2 (Br 2 SN)(CH 3 OH)] (2), and [MoO 2 (I 2 SN)(CH 3 OH)] (3). Various techniques like NMR (1H and 13C), FT-IR, Mass, TGA, elemental (CHN), and single-crystal X-ray diffraction analysis (for H 2 Cl 2 SN · H 2 O , 2a , [MoO 2 (Br 2 SN)(C 2 H 5 OH)], and 3a , [MoO 2 (I 2 SN)(H 2 O)].DMF) were utilized to characterize the synthesized compounds. The data collected from diffraction studies revealed that the geometry around Mo(VI) ions was distorted octahedral. Additionally, all complexes were successfully screened as catalysts for the selective oxidation of benzylic alcohols employing ethanol and hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Host–guest assemblies open up opportunities for developing novel functional CLUSPOM multicomponent systems based on transition metal clusters (CLUS), polyoxometalates (POMs) and macrocyclic organic ligands. In water–ethanol solution γ-cyclodextrin (γ-CD) interacts with halide metal clusters [M6Cl14]2– (M = Mo, W) to form sandwich-type structures. The supramolecular association between the clusters and CDs, however, remains weak in solution, and the interactions are not strong enough to prevent the hydrolysis of the inorganic guest. Although analysis of the resulting crystal structures reveals inclusion complexation, 1H NMR experiments in solution show no specific affinity between the two components. The luminescent properties of the host–guest compounds in comparison with the initial cluster complexes are also studied to evaluate the influence of CD.

Two new complexes, including [MoO2(L1)(CH3OH)] and [MoO2(L2)(CH3OH)], with tridentate ONO–donor Schiff base ligands (H2L1: (E)-N'-(2-hydroxy-3-methoxybenzylidene)isonicotinohydrazide and H2L2: (E)-N'-(5-chloro-2-hydroxybenzylidene)isonicotinohydrazide) have been synthesized and characterized spectroscopically through FT-IR and 1H-NMR and by elemental analyses. Their solid-state structures were also confirmed by single-crystal X-ray diffraction (SC-XRD) technique. These tridentate Schiff base ligands coordinated to the metal ion via phenolate oxygen, imine nitrogen and enolic oxygen atoms. In the complexes, the molybdenum center adapts a slightly distorted octahedral geometry, by using three O,N,O-donor atoms of the tridentate ligands, methanol and an oxo group employing the axial positions, while another oxo group makes the equatorial plane. Moreover, the complexes were utilized in oxidizing the different sulfides as an efficient homogeneous catalyst in the presence of tert-butyl hydroperoxide (TBHP) as an oxidizing agent in 1,2-dichloroethane (DCE) as a solvent under refluxed conditions. This method has numerous ascendancies such as high yield, short reaction time and excellent selectivity to produce corresponding sulfoxides without overoxidation to sulfones. [ABSTRACT FROM AUTHOR]

Despite the numerous studies on Chevrel phases, their building blocks – molecular compounds containing the {Mo6Q8} cluster core – are hardly presented in the literature. Here we present rare examples of phosphane molybdenum chalcogenide clusters – [{Mo6Q8}(Ph2PC2H4COOH)6] (Q = S or Se) – which have been obtained by the direct interaction of (Bu4N)2[{Mo6Cl8}Cl6] with in situ generated Na2Q in the presence of a phosphane pro-ligand. Crystal structure determination has confirmed the formation of a homoleptic six-substituted neutral complex. The redox and optical properties were also studied. Due to the presence of six carboxylate groups in phosphane ligands, both clusters form a stable solution in alkaline water. Besides the known K7[{Mo6Se8}(CN)6]·8H2O, the compounds obtained here are the only examples of water-soluble complexes of such types. [ABSTRACT FROM AUTHOR]

Two cis-dioxomolybdenum complexes based on salan ligands with different backbones are reported. The first complex, dioxido{2,2'-[l,2-phenylenebis(iminomethylene)]bis­(phenolato)}molybdenum(VI) dimethylformamide disolvate, [Mo(C20H18N2O2)O2]·2C3H7NO (PhLMoO2, 1b), features a phenyl backbone, while the second complex, (6,6'-{[(cyclohexane-1,2-di­yl)bis(azanediyl)]bis­(methyl­ene)}bis­(2,4-di-tert-butyl­phenolato))dioxidomolybdenum(VI) methanol disolvate, [Mo(C36H56N2O2)O2]·2CH3OH (CyLMoO2, 2b), is based on a cyclo­hexyl backbone. These complexes crystallized as solvated species, 1b·2DMF and 2b·2MeOH. The salan ligands PhLH2 (1a) and CyLH2 (2a) coordinate to the molybdenum center in these complexes 1b and 2b in a κ2N,κ2O fashion, forming a distorted octa­hedral geometry. The Mo--N and Mo--O distances are 2.3475 (16) and 1.9567 (16) Å, respectively, in 1b while the corresponding measurements are Mo--N = 2.3412 (12) Å, and Mo--O = 1.9428 (10) Å for 2b. A key geometrical feature is that the N--Mo--N angle of 72.40 (4)° in CyLMoO2 is slightly less than that of the PhLMoO2 angle of 75.18 (6)°, which is attributed to the flexibility of the cyclohexane ring between the nitro­gen as compared to the rigid phenyl ring in the PhLMoO2. [ABSTRACT FROM AUTHOR]

The study of quadruple bonds between transition metals, in particular those of dimolybdenum, has revealed much about the two-electron bond. The solid-state structure of the quadruple-bonded dimolybdenum(II) complex tetrakis[μ-4-(trifluoromethyl)benzoato-κ²O:O′]bis[(tetrahydrofuran-κO)molybdenum(II)] 0.762-pentane 0.238-tetrahydrofuran solvate, [Mo2(p-O2CC6H4CF3)4·2THF]·0.762C5H12·0.238C4H8O or [Mo2(C8H4F3O2)4(C4H8O)2]·0.762C5H12·0.238C4H8O is reported. The complex crystallizes within a triclinic cell and low symmetry (P[\overline{1}]) results from the intercalated pentane/THF solvent molecules. The paddlewheel structure at 100 K has inversion symmetry and comprises four bridging carboxylate ligands encases the Mo2(II,II) core that is characterized by two axially coordinated THF molecules and an Mo--Mo distance of 2.1098 (7) Å. [ABSTRACT FROM AUTHOR]

Systematic crystallization of KLn(MoO4)2 double molybdate micro/nanocrystals was achieved in this work for the family of lanthanide elements (excluding Pm) and Y via hydrothermal reaction under the optimized conditions of pH = 7, Mo/Ln molar ratio R = 5 and 200 °C, with which the intrinsic influence of lanthanide contraction on phase preference, crystallite morphology (size/shape) and crystal structure was clearly revealed. Extended synthesis also produced KLa1−xEux(MoO4)2 (KLM:xEu) and KY1−yEuy(MoO4)2 (KYM:yEu) red phosphors, and detailed spectral analysis found that the layered structure of orthorhombic KYM allows Eu3+ to have a high quenching content of ∼70 at% (y = 0.7) and higher quantum efficiency and thermal stability of luminescence. Application also indicated that the KYM:0.7Eu optimal phosphor has the potential for optical temperature sensing with the thermally coupled 5D0 and 5D1 energy levels of Eu3+. [ABSTRACT FROM AUTHOR]

Two new cluster complexes (Bu4N)2[Mo6X8(OOC–C≡CH)6] (1) (X = Br) and (2) (X = I) are synthesized by the reaction of (Bu4N)2[Mo6X8(OOCCH3)6] (X = Br, I) with HOOC–C≡CH propiolic acid, their crystal structures are determined, and the luminescent properties are studied for powder samples at different temperatures. According to X-ray crystallographic data, molybdenum atoms are monodentately coordinated by oxygen atoms of the carboxyl group at Mo–O distances of 2.108(2)-2.121(16) Å. The propiolate complexes are characterized by electrospray mass spectrometry, 1Н and 13С NMR, elemental analysis, and IR spectroscopy. [ABSTRACT FROM AUTHOR]

New dioxidomolybdenum(VI) complexes with the formula [MoO2L(MeOH)], derived from N'-(5-chloro-2-hydroxybenzylidene)-2-methylbenzohydrazide (H2L1) and N'-(3,5-dichloro-2-hydroxybenzylidene)-2-methylbenzohydrazide (H2L2) were prepared. Crystal and molecular structures of the complexes were determined by single crystal X-ray diffraction method. Both complexes were further characterized by elemental analysis and FT-IR spectra. Single crystal X-ray structural studies indicate that the hydrazones L1 and L2 coordinate to the MoO2 cores through the enolate oxygen, phenolate oxygen and azomethine nitrogen. The Mo atoms in both complexes are in octahedral coordination. Catalytic properties for epoxidation of styrene by the complexes using PhIO and NaOCl as oxidant have been studied.

Three cyclopentadienylmolybdenum(II) propionyl complexes featuring triarylphosphine ligands with different para substituents, namely, dicarbonyl(η5-cyclopentadienyl)propionyl(triphenylphosphane-κP)molybdenum(II), [Mo(C5H5)(C3H5O)(C18H15P)(CO)2], (1), dicarbonyl(η5-cyclopentadienyl)propionyl[tris(4-fluorophenyl)phosphane-κP]molybdenum(II), [Mo(C5H5)(C3H5O)(C18H12F3P)(CO)2], (2), and dicarbonyl(η5-cyclopentadienyl)propionyl[tris(4-methoxyphenyl)phosphane-κP]molybdenum(II) dichloromethane solvate, [Mo(C5H5)(C3H5O)(C21H21O3P)(CO)2]·CH2Cl2, (3), have been prepared from the corresponding ethyl complexes via phosphine-induced migratory insertion. These complexes exhibit four-legged piano-stool geometries with molecular structures quite similar to each other and to related acetyl complexes. The extended structures of the three complexes differ somewhat, with the para substituent of the triarylphosphine of (2) (fluoro) or (3) (methoxy) engaging in non-classical C--H⋯F or C--H⋯O hydrogen-bonding interactions. The structure of (3) exhibits modest disorder in the position of one Cl atom of the dichloromethane solvent, which was modeled with two sites showing approximately equivalent occupancies [0.532(15) and 0.478(15)]. [ABSTRACT FROM AUTHOR]

The first iodide cluster of molybdenum with the metal cage in the form of a tetragonal pyramid (Bu4N)[Mo5OI13]·THF (I) and cocrystallizate (Bu4N){[Mo5OI13]0.9[Mo6I14]·THF (II) are synthesized for the first time by heating a LiI–I2–Mo mixture in a temperature range of 300–400°С followed by the extraction of the product. Complexes I and II are studied by X-ray diffraction analysis (CIF files CCDC nos. 2063029 (I) and 2063030 (II)). The molybdenum atoms in [Mo5OI13]– form a square pyramid with Mo–Mo distances of 2.67 Å between the basal molybdenum atoms and the Mo–Mo distances equal to 2.72 Å between the apical and basal molybdenum atoms. The oxygen atom is coordinated to the pyramid base (Mo–μ4-O 2.10 Å). The cluster anion [Mo5OI13]– can be presented as the octahedral cluster anion [Mo6I14]2– in which the position of the {MoI}– fragment (d0, 6e) is occupied by the isoelectronic oxygen atom (s2p4, 6e). In the structure of compound II, the [Mo5OI13]– and [Mo6I14]2– cluster anions occupy close atomic positions. [ABSTRACT FROM AUTHOR]

The title compound, [Mo(C5H7O2)2O2] or cis-[MoO2(acac)2] (acac is acetylacetonate), contains a molybdenum(VI) atom coordinated by two acetylacetonate ligands and two doubly bonded oxido ligands in a distorted octahedral shape. The molecule is chiral and the asymmetric unit contains two independent molecules (one Δ, one Λ). Extensive C—H...O contacts are present throughout the structure. Data were collected at 100 K, providing higher precision of unit-cell parameters and atomic positions than previous determinations [Kamenar et al. (1973). Cryst. Struct. Commun. 2, 41–44.; Krasochka et al. (1975). Zh. Strukt. Khim. 16, 696–698].

(PyH)2[MoOCl5] was obtained in the form of emerald green crystals unintentionally from (PyH)5[MoOCl4(H2O)]3Cl2 in acetonitrile. (PyH)2[MoOCl5] has been used as a starting material in molybdenum(V) coordination chemistry for decades, yet its true identity has not been known until now. The X-ray structure analysis has undoubtedly confirmed the existence of this compound. The [MoOCl5]2− ion displays the usual structural characteristics of the mononuclear MoO3+-containing compounds.

The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of the longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0-300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions. [ABSTRACT FROM AUTHOR]

Synthetic complexes containing a cis-[MoO2]2+ core are well-established models for the molybdenum co-factor (Moco). Here we report the crystal structure of such a model complex bearing a tetradentate amine bis(phenolate) ligand with fluorine substituents on the phenolate rings, namely, [2,2′-({[2-(dimethylamino)ethyl]azanediyl}bis(methylene))bis(4,6-difluorophenolato)]dioxidomolybdenum(VI)), [Mo(C18H18F4N2O2)O2]. Distortion from idealized octahedral symmetry about the Mo center is evident in the large O=Mo=O angle [108.54 (4)°] and the small N–Mo–Ophenolate angles [79.79 (4), 81.21 (3), 77.83 (3), and 84.59 (3)°]. The dihedral angle between the phenolate rings is 60.06 (4)°, and π–π stacking is observed between aromatic rings related by inversion (1 − x, 1 − y, 1 − z). The lower data-collection temperature of 150 K vs room-temperature data collection reported previously [KOWXIF; Cao et al. (2014). Transit. Met. Chem. 39, 933–937] and larger 2θ range for data collection (5.8–66.6° versus 6–54.96°) led to a structure with lower R1 and ωR2 values (0.019 and 0.049 vs 0.0310 and 0.0566 for KOWXIF). Comparison of the metrical parameters with KOWXIF suggests that this dataset offers a more realistic depiction of bonding within the MoVI=O moiety.

The title compound, tri­carbonyl­tris­(dimethyl sulfoxide)­molybdenum, [Mo(C2H6OS)3(CO)3] or fac-[Mo(CO)3(DMSO)3], crystallizes in the triclinic space group P1̅ with two mol­ecules in the unit cell. The geometry around the central molybdenum is slightly distorted octa­hedral and the facial isomer is found exclusively. The packing within the crystal is stabilized by three-dimensional non-classical inter­molecular hydrogen-bonding contacts between individual methyl substituents of di­methyl sulfoxide and the oxygen atoms of either another di­methyl sulfoxide or a carbonyl ligand on adjacent complex mol­ecules. The observed bond lengths in the carbonyl ligands and between carbonyl carbon atoms and molybdenum are correlated to the observed FT–IR bands for the carbonyl stretches and compared to respective metrical parameters of related complexes. [ABSTRACT FROM AUTHOR]