Molybdenum Cluster Complexes Research Articles

Synthesis, crystal structure, and luminescence properties of complexes (4-ViBnNMe3)2[{M6(µ3-I)8}I6] (M = Mo, W; (4-ViBnNMe3)+ is trimethyl(4-vinylbenzyl)ammonium)

Two new compounds based on octahedral molybdenum and tungsten iodide cluster complexes of the composition (4-ViBnNMe3)2[{M6(µ3-I)8}I6] (M = Mo, W; (4-ViBnNMe3)+ is trimethyl(4-vinylbenzyl)ammonium) were synthesized and structurally characterized. The luminescence properties of powder samples of the synthesized compounds and of the salts (Bu4N)2[{M6(µ3-I)8}I6] described earlier were investigated. Due to the presence of the vinylcontaining cation, these compounds can be involved in radical copolymerization in order to produce polymeric luminescent materials.

Prospects of molybdenum and rhenium octahedral cluster complexes as X-ray contrast agents

Investigation of new X-ray contrast media for radiography is an important field of science since discovering of X-rays in 1895. Despite the wide diversity of available X-ray contrast media the toxicity, especially nephrotoxicity, is still a big problem to be solved. The octahedral metal-cluster complexes of the general formula [{M6Q8}L6] can be considered as quite promising candidates for the role of new radiocontrast media due to the high local concentration of heavy elements, high tuning ability of ligand environment and low toxicity. To exemplify this, the X-ray computed tomography experiments for the first time were carried out on some octahedral cluster complexes of molybdenum and rhenium. Based on the obtained data it was proposed to investigate the toxicological proprieties of cluster complex Na2H8[{Re6Se8}(P(CH2CH2CONH2)(CH2CH2COO)2)6]. Observed low cytotoxic and acute toxic effects along with rapid renal excretion of the cluster complex evidence its perspective as an X-ray contrast media for radiography.

Luminescent hydrogel particles prepared by self-assembly of β-cyclodextrin polymer and octahedral molybdenum cluster complexes.

A series of luminescent octahedral molybdenum cluster complexes were obtained by treating Na2[Mo6I8(OMe)6] with icosahedral closo-dicarbaborane C-carboxylic acids in refluxing tetrahydrofuran. The study of the photophysical properties of Na2[Mo6I8(1-OOC-1,2-closo-C2B10H11)6] (1), Na2[Mo6I8(1-OOC-1,7-closo-C2B10H11)6] (2), and Na2[Mo6I8(1-OOC-1,12-closo-C2B10H11)6] (3) in acetonitrile revealed a red luminescence with high quantum yields up to 0.93 for 2, an efficient quenching of the luminescence by oxygen, and high quantum yields of singlet oxygen formation of approximately 0.7. Self-assembly between compound 2 and β-cyclodextrin polymer led to monodisperse hydrogel particles with a diameter of approximately 200 nm and unchanged luminescence spectra and kinetics features over 14 days. In contrast, bare cluster complex 2 in water formed aggregates and hydrolyzed over the time as indicated by a progressive red shift of the luminescence maxima. The invariance of key photophysical parameters of the hydrogel particles coupled with a high oxygen sensitivity of the luminescence are attractive features for long-term biological experiments involving optical oxygen probing. In addition, this hydrogel is a singlet oxygen sensitizer in water with promising properties for photodynamic therapy.

A family of octahedral molybdenum cluster complexes [Mo6Cl8(H2O)n(OH)6−n]n−2 with n = 0–6 as a pH-sensors: A theoretical study

Theoretical computations of a series of clusters [Mo6Cl8(H2O)n(OH)6−n]n−2 are presented. UV–Vis absorption spectra, the ground states (S0) and the lowest excited states (S1 and T1) were examined. Energy diagrams for luminescent decay were built in order to get insights about the emission processes of these systems. The fact that the systems show different emission energy profiles when the aqua and hydroxo coordinations are changed, indicates pH-dependence and supports the statement that these clusters are candidates to act as pH-sensors. Those properties are also shown by a reported family of luminescent [Re6S8(H2O)n(OH)6−n]n−4 clusters, with the same structure of the systems studied here.

A comparative study of the redox and excited state properties of (nBu4N)2[Mo6X14] and (nBu4N)2[Mo6X8(CF3COO)6] (X = Cl, Br, or I)

The excited-state dynamics, luminescence, and redox properties of a series of hexanuclear molybdenum cluster complexes, (nBu4N)2[Mo6X14] and (nBu4N)2[Mo6X8(CF3COO)6] (X = Cl, Br, or I), were investigated. Substitution of the apical halogen ligands for the trifluoroacetate ligands increased the oxidation potentials and induced a blue shift in the absorption and luminescence bands as well as a considerable increase in the luminescence quantum yields for heavy inner ligands. Time-resolved transient absorption measurements showed that the intersystem crossing from the excited singlet states is ultrafast with time constants ranging between <120 fs and 1.68 ps and leads to hot triplet states. The following cooling occurred at a ps time scale and was assigned to electronic redistribution within the emissive triplet state sublevels. The formation of singlet oxygen, O2((1)Δg), suggested earlier on the basis of photooxidation experiments for some complexes, was revised by direct measurements of O2((1)Δg) phosphorescence. We showed the effects of the attached ligands on key physico-chemical and photophysical parameters of the title complexes. The synthesis and structural characterisation of a new cluster complex, (nBu4N)2[Mo6Br8(CF3COO)6], completed the series. Our results demonstrated that the complexes with heavy inner ligands (Br, I) and apical trifluoroacetate ligands were photochemically and electrochemically stable, highly luminescent, and good sensitisers of O2((1)Δg).

Synthesis of hexanuclear molybdenum clusters containing phosphine oxide ligands

We report the direct preparation of two new octahedral hexanuclear molybdenum cluster complexes containing phosphine oxide ligands, namely, [Mo6(μ3-Cl)8{OP(n-Pr)3}2Cl4] and [Mo6(μ3-Cl)8(OPEt3)2Cl4], from Mo6Cl12 and the corresponding phosphine oxide ligands. Both of these complexes were characterized by NMR and IR spectroscopies, cyclic voltammetry and elemental analysis. Further, a single-crystal X-ray structure determination of [Mo6(μ3-Cl)8{OP(n-Pr)3}2Cl4] was obtained: [Mo6(μ3-Cl)8{OP(n-Pr)3}2Cl4] crystallizes in the monoclinic space group, P21/n with a = 10.0685(16) A, b = 15.617(2) A, c = 15.693(3) A, β = 91.799(5)°, and R1 = 0.0288. A trans arrangement of the phosphine oxide ligands was observed, where both ligands are bonded to the molybdenum cluster through the oxygen atoms. We also investigated the reaction of [Mo6(μ3-Cl)8{P(n-Pr)3}2Cl4] with a variety of oxidizing agents and found that the coordinated tri(n-propyl)phosphine ligands are cleanly oxidized by H2O2 to the corresponding phosphine oxides, yielding [Mo6(μ3-Cl)8{OP(n-Pr)3}2Cl4].

Syntheses and structures of Tetranuclear Cluster complexes of molybdenum [Mo4(?3-S)2(?2-S)4 X 2-(PMe3)6] (X = SH, Cl, Br, I, SCN) and [Mo4(?3-S)2-(?2-S)4 (dtc)2(PMe3)4] (dtc = diethyldithiocarbamate)

A molybdenum cluster complex [Mo4(μ3-S)2(μ2-S)4)(SH)2(PMe3 6] has been synthesized by the reaction of (NH4)2Mo3S13 with trimethylphosphine. The cluster core is composed of four molybdenum atoms arranged in the rhombus bridged by two capping and four bridging sulfur atoms. Two SH and six tri-methylphosphine ligands are coordinated to the terminal positions. The mean oxidation stares of molybdenum is +3.5 and there are five Mo-Mo bonds consistent with ten metal cluster electrons. The complex has been converted into [Mo4(μ3-S)2(μ2-S)4 X 2(PMe3)6] (X=Cl, Br, I, SCN) and [Mo4μ3-S2(μ2-S)4 (die)2(PMe3)4] (dtc - diethyldithiocarbamate). In the case of the dtc complex, two terminal trimetlaylphosphine ligands are displaced and dtc ligands are coordinated in chelate fashion. The structures of the SH, Cl, Br, and dtc complexes have been determined by X-ray crystallography. Molecular orbital calculations with DV-Xα method has shown large HOMO-LUMO gaps (1.52-1.74eV) for [Mo4S6 X 2(PH3)4] (X= SH, Cl, and Br).

A Synthetic and X-Ray Crystallographic Study of Cobalt and Molybdenum Cluster Complexes of the 2-Fenchyl Cation: Metal-Mediated Wagner-Meerwein Rearrangements

A Synthetic and X-Ray Crystallographic Study of Cobalt and Molybdenum Cluster Complexes of the 2-Fenchyl Cation: Metal-Mediated Wagner-Meerwein Rearrangements

Synthesis, Structure, and Molecular Orbital Calculation of the Bicapped Triangular Molybdenum Cluster Complex [Mo3S5(PMe3)6

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, Structure, and Molecular Orbital Calculation of the Bicapped Triangular Molybdenum Cluster Complex [Mo3S5(PMe3)6]Kiyoshi Tsuge, Hideo Imoto, and Taro SaitoCite this: Inorg. Chem. 1995, 34, 13, 3404–3409Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://doi.org/10.1021/ic00117a006RIGHTS & PERMISSIONSArticle Views169Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

Molecular Orbital Calculations of Octahedral Molybdenum Cluster Complexes with the DV-X.alpha. Method

Discrete variational-{Chi}{alpha} molecular orbital methods were applied to octahedral cluster complexes, [Mo{sub 6}X{sub 8}-(PH{sub 3}){sub 6}](X = S and Se). This structure is of interest due to its role in superconductivity of Chevrel plates. Level energies are discussed and factors contributing to their separations are categorized. Agreement with empirical XPS data is excellent.

Synthesis of an equilateral triangular molybdenum cluster complex [Mo3(.mu.3-S)2(.mu.-S)3(PMe3)6] with eight cluster valence electrons

Synthesis of an equilateral triangular molybdenum cluster complex [Mo3(.mu.3-S)2(.mu.-S)3(PMe3)6] with eight cluster valence electrons

Synthesis of Trinuclear Molybdenum Cluster Complex with Novel Skeleton, [Mo3(μ3-CCH3)(μ3-O)(μ-C6H5COO)6(CH3OH)3]Cl through Bridging Carboxylate Ligand Substitution

Abstract [Mo3(μ3-CCH3)(μ3-O)(μ-CH3COO)6(H2O)3]+ undergoes bridging acetates substitution with benzoate ions in CH3OH-CH3CN mixed solvent to give [Mo3(μ3-CCH3)(μ3-O)(μ-C6H5COO)6(CH3OH)3]+, which can never be synthesized in principle by the conventional direct method.

Kinetic studies on the terminal-ligand-substitution reactions of acetate-bridged trinuclear molybdenum and tungsten cluster complexes, [Mo3(.mu.3-CCH3)(.mu.3-O)(.mu.-CH3COO)6(L)3]+ (L = H2O or pyridine) and [W3(.mu.3-O)(.mu.-CH3COO)6(H2O)3]2+

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic studies on the terminal-ligand-substitution reactions of acetate-bridged trinuclear molybdenum and tungsten cluster complexes, [Mo3(.mu.3-CCH3)(.mu.3-O)(.mu.-CH3COO)6(L)3]+ (L = H2O or pyridine) and [W3(.mu.3-O)(.mu.-CH3COO)6(H2O)3]2+Kou Nakata, Akira Nagasawa, Nobuyuki Soyama, Yoichi Sasaki, and Tasuku ItoCite this: Inorg. Chem. 1991, 30, 7, 1575–1579Publication Date (Print):April 1, 1991Publication History Published online1 May 2002Published inissue 1 April 1991https://doi.org/10.1021/ic00007a028RIGHTS & PERMISSIONSArticle Views207Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (557 KB) Get e-Alerts Get e-Alerts

A study of supported molybdenum cluster complexes as catalyst precursors: Part I. Preparation, spectroscopic characterization and thermal stability of clusters supported on γ-alumina

The preparation of a series of molybdenum cluster complexes supported on γ-alumina is described, with selection of six clusters rationalized on the basis of structural types and ease of synthesis. Four trinuclear, one tetranuclear and one hexanuclear cluster were examined, with molybdenum loadings of ca. 4.5% by weight. Infrared and electronic spectral methods were used to ascertain whether the clusters retained their structural integrity after impregnation onto the alumina, and the thermal stability of both the supported and unsupported clusters was determined by differential thermal analysis.

A study of supported molybdenum cluster complexes as catalyst precursors: Part II. Evaluation of the catalytic activity of clusters supported on γ-alumina and fluorided γ-alumina

The supported molybdenum clusters previously described [1] were tested for their potential activity in the catalysis of cumene hydrocracking, thiophene hydrogenolysis, propene hydrogenation and, in some instances, gas oil hydrocracking. The effect of modifying the alumina support by the addition of fluoride ion was also investigated for those materials which showed promising catalytic activity, and the molybdenum loading was varied over the calculated range 4 – 10%. The effect of cobalt and nickel promoters was then examined. The results were compared with those obtained from conventional catalysts, prepared by impregnation of γ-alumina with molybdate with and without fluoride, cobalt and nickel additives. The most active catalysts tested were those prepared from the hexanuclear cluster, (H 3O +) 2[Mo 6Cl 14] 2−·6H 2O. These catalysts gave surprisingly high conversions in cumene hydrocracking, and had substantial activity in HDS studies. As hydrocracking catalysts for application to commercial feedstocks they showed considerable promise, especially when the Mo loading factor was taken into account. XPS studies of one of this series of catalysts suggested that in the hydrocracking of cumene and in the hydrodesulfurization of thiophene, the integrity of the cluster is destroyed during use, and hence the clusters should be regarded as precursors of the active catalytic species rather than being the active species themselves.

Complexation reactions of tetrathiomolybdate ions with binuclear molybdenum and rhenium metal cluster complexes

Syntheses are reported for previously unknown hetero- and homometallic polynuclear thio complexes, (n-Bu4,N)2 (Mo6S20), (n-Bu24N)2)Re2Mo4S16), and K4(Mo6S16).

Preparation of triangular and cubic molybdenum clusters as aqua ions

Further use of an electrochemical procedure for the formation of triangular and cubic molybdenum cluster complexes as aqua ions is reported.