Cationic Molybdenum Research Articles

Lubrication Properties of Cationic Surfactant-Adsorbed Molybdenum Disulfide as a Bonded Film Lubricant

Cationic surfactant was adsorbed to MoS2 on prevent water adsorption, which causes the friction and wear increase of MoS2 in humid air. The surfactant-adsorbed MoS2 boas applied as a bonded film lubricant, and friction and wear tests were carried out. The friction indicated a value around 20% smaller and the wear considerably decreased compared with those of the pure MoS2 bonded film lubricant. The surface analyses indicated that the surfactant adsorbed mainly to the crystallite edge of the MoS2 molecular structure and a little to the basal plane.

Synthesis and cleavage reactions of metal-metal-bonded [Mo(2)(S(2)CNR(2))(6)](OTf)(2), a source of the Tris(dithiocarbamato)molybdenum(IV) fragment.

Halide abstraction from the chlorotris(dialkyldithiocarbamato)molybdenum(IV) complexes MoCl(S(2)CNR(2))(3) (R = Et, Me) with silver triflate produces the diamagnetic dimeric complexes [Mo(2)(S(2)CNR(2))(6)](OTf)(2) in good yield. The crystallographically determined structure of the diethyldithiocarbamato complex indicates that the dimer consists of two pentagonal bipyramids sharing an axial edge, with a Mo-Mo separation (2.8462(8) A) indicative of a metal-metal bond. A qualitative analysis of the bonding indicates that this bond is of order 2 and consists of one normal sigma bond and one relatively weak "skewed pi" interaction. The dimers [Mo(2)(S(2)CNR(2))(6)](OTf)(2) react with a variety of reagents to give monomeric seven-coordinate complexes, including the new cationic molybdenum(IV) complex [Mo(PMe(2)Ph)(S(2)CNEt(2))(3)](OTf), which has been structurally characterized. Kinetic studies of the reaction of [Mo(2)(S(2)CNEt(2))(6)](OTf)(2) with halides indicate the presence of competing dissociative and associative substitution pathways, although neutral donors may react by different mechanisms.

Cationic molybdenum complexes with P-coordinated (diphenylphosphino)alkynes

New cationic P-coordinated (diphenylphosphino)alkyne complexes with molybdenum [(Mp)Ph 2PCCR][BF 4] {R=H, Me, t Bu, Ph, Tol; Mp=(C 5H 5)Mo(CO) 3} have been prepared from reaction between a (diphenylphosphino)alkyne Ph 2PCCR and the dinuclear complex [(C 5H 5)Mo(CO) 3] 2, with Ag(I) as oxidant. The bis(diphenyphosphosphino)acetylene Ph 2PCCPPh 2 led to the following homo- and heteronuclear metal complexes by the same method: [(Mp)Ph 2PCCPPh 2][BF 4], [(Mp)Ph 2PCCPPh 2(Mp)][BF 4] 2 and [(Mp)Ph 2PCCPPh 2(Fp)][BF 4] 2 {Fp=(C 5H 5)Fe(CO) 2}. The reaction of the P-coordinated molybdenum complexes [(Mp)Ph 2PCCR][BF 4] with dicobalt octacarbonyl at room temperature afforded the cationic heterometallic complexes [(Mp)Ph 2PC 2R{Co 2(CO) 6}][BF 4]. All complexes were characterised by microanalysis and IR, 1H-, 13C- and 31P-NMR spectroscopy.

Modification of Potassium-Containing Zeolites Loaded with Mo3S44+ Clusters by Solid-State Reaction between Zeolites and KCl

By aqueous ion exchange, cationic molybdenum sulfide Mo3S44+ clusters have been successfully introduced into KY and KL without destruction of the zeolite structures as verified by the measurements ...

Zeolite-supported hydrodesulfurization catalysts prepared by ion exchange with Mo and Mo [sbnd]Ni sulfide clusters

Zeolites NaY, HUSY and KL were ion-exchanged with a cationic molybdenum sulfide cluster [Mo 3S 4(H 2O) 9] 4+ with incomplete cubane-type structure and a cationic nickel-molybdenum mixed sulfide cluster [Mo 3NiS 4Cl(H 2O) 9] 3+ with complete cubane-type structure. The UV-visible spectra and EXAFS analysis data exhibited that the structure of the molybdenum cluster was maintained after ion exchange. These zeolite catalysts showed activity for benzothiophene hydrodesulfurization; especially, involvement of Ni resulted in great enhancement of the hydrodesulfurization activity.

95Mo NMR Studies on Cationic Phosphenium Complexes of Molybdenum

The 95Mo NMR spectra of cationic molybdenum phosphenium complexes have been measured. Going from fac-[(bpy)(CO)3Mo{PN(Me)CH2CH2NMe(OMe)}] (1a) to fac-[(bpy)(CO)3Mo{PN(Me)CH2CH2NMe}]+ (fac-1b) to mer-[(bpy)(CO)3Mo{PN(Me)CH2CH2NMe}]+ (mer-1b) causes deshielding of the 95Mo doublet resonance (δ −1081 (1a), −1049 (fac-1b), −1015 (mer-1b)), an increase in the Mo−P coupling constant (193 Hz (1a), 264 Hz (fac-1b), 337 Hz (mer-1b)), and an increase in the line width (35 Hz (1a), 90 Hz (fac-1b), 300 Hz (mer-1b)). The conversion of fac-[(bpy)(CO)3Mo{PN(Me)CH2CH2O(OMe)}] (fac-2a) into mer-[(bpy)(CO)3Mo{PN(Me)CH2CH2O}]+ (mer-2b) showed a similar trend in 95Mo NMR data, though fac-[(bpy)(CO)3Mo{PN(Me)CH2CH2O}]+ was not detected in this case. mer-2b exhibits the largest Mo−P coupling constant (343 Hz) among those reported so far. These changes can be reasonably attributed to a dominant contribution from the imbalance of electron density at the Mo in the Ramsey equation due to a significant double-bond character between the molybdenum and the phosphenium phosphorus. Comparison of coupling constants between M and a phosphenium P in [(bpy)(CO)3M{PN(Me)CH2CH2NMe}]+ (M = Mo, W) revealed that the ratio 1JW-P/1JMo-P is 1.67, which is very close to the ratio (1.76) reported for many series of M−phosphine (or phosphite) complexes (M = Mo, W). The 95Mo NMR spectra of cis- and trans-[(bpy)(CO)2Mo{PN(Me)CH2CH2X(OMe)}{PN(Me)CH2CH2X}]+ (X = NMe, cis-1c, trans-1c; X = O, cis-2c, trans-2c) have also been measured; the chemical shifts are understood similarly in terms of the imbalance of electron density at Mo.

Halide abstraction as a route to cationic molybdenum(IV) compounds: Crystal and molecular structure of [CpMoCI(MeCN) 4][SbCl 6] 2 · MeCN

Treatment of CpMoC1 3(MeCN) 2 with SbCl 5 in acetonitrile solution provides the solvated cationic series [CpMoCl 2(MeCN) 3] +, [CpMoCl(MeCN) 4] 2+ and [CpMo(MeCN) 6] 3+ as hexachloroantimon(V)ate salts following sequential halide abstraction. Characterization follows from microanalytical and spectroscopic (IR, and 1H NMR) data and, in the case of [CpMoCl(MeCN) 4][SbCl 6] 2 · MeCN, by X-ray crystallographic studies. The structure is disordered but individual cations contain a six coordinated pseudo-octahedral metal geometry in which the cyclopentadienyl ligand (regarded as unidentate) and the chlorine atom occupy axial positions with an equatorial array of four acetonitrile ligands.

Reactions of a Cationic Molybdenum Complex with Olefins. 2. Oligomerization of Terminal Branched Olefins

The oligomerization of 2-methylpropene and of other terminal disubstituted olefins in dichloromethane solution was catalyzed by [(CpMo)[sub 2](S[sub 2]CH[sub 2])([mu]-S)([mu]-SR)]OTf, where R = H, 1, or CMe[sub 3], 2. Oligomers of 2-methylpropene of the formula (C[sub 4]H[sub 8])[sub n], where n = 2-8, were detected, and the major C[sub 8] and C[sub 12] isomers have been identified. The distribution of oligomers was consistent with a carbocationic coupling mechanism. Molybdenum products isolated from the 2-methylpropene coupling reaction were found by mass spectrometry to have the formula [(CpMo)[sub 2](S[sub 2]CH[sub 2])([mu]-S) ([mu]-S(C[sub 4]H[sub 8])[sub n]H)][sup +], where n = 1-3. The role of the molybdenum catalysts as proton donors and as carbenium ion donors has been investigated, and a mechanism for oligomerization has been proposed which also takes into account the known stoichiometric reactions of 1 and 2 with olefins. 16 refs., 1 fig., 2 tabs.

Das reaktionsverhalten von Cp 2MoCl 2 gegenüber WF 6 und NOBF 4 — struktur von [Cp 2MoCl 2][BF 4

The oxidation of CpMoCl 2 ( 1) with WF 6 or NOBF 4 to yield cationic molybdenum(V) species was estimated on the basis of a simple Born-

Reactions of co-ordinated ligands. Part 55. Molybdenummediated addition of alkynes to cyclooctatetraene; one-electron oxidation and protonation of η3-allyl(η4-1,3-diene)(η-cyclopentadienyl or η5-indenyl) molybdenum complexes, and crystal structures of [Mo(η3,η4-C12H13)(η-C5H5)], [Mo(η2,η4-C14H17)(η-C5H5)][BF4] and [Mo(η2,η4-C12H13)(µMo,C-H)(η5-C9H7)][CF3SO3

Reaction of [Mo(NCMe)(η2-MeC2Me)2(η-C5H5)][BF4] with cyclooctatetraene (cot) in acetonitrile in the presence of the proton scavenger Na2CO3 affords the neutral complex [Mo(η3,η4-C12H13)(η-C5H5)]1. Analogous reactions between cot and [Mo(NCMe)(η2-EtC2Et)2(η-C5H5)][BF4], [Mo(NCMe)(η2-MeC2Me)2(η5-C9H7)][BF4] and [Mo(NCMe)(η2-EtC2Et)2(η5-C9H7)][BF4] give [Mo(η3,η4-C14H17)(η-C5H5)]2, [Mo(η3,η4-C12H13)(η5-C9H7)]3, and [Mo(η3,η4-C14H17)(η5-C9H7)]4 in good yield. A single-crystal X-ray diffraction study on 1 established the presence of an unusual bicyclo[4.2.2]decane ligand, to which a Mo(η-C5H5) fragment is η3,η4-bonded. Although this structure suggests that these complexes are formed via a (6 + 2)π addition reaction, it is proposed that a stepwise process is involved. The chemical reactivity of the complexes 1–4 has been explored. Reaction of 1 or 3 with [CPh3][BF4] affords respectively the cations [Mo(η4,η4-C12H12)(η-C5H5)][BF4]7 and [Mo(η4,η4-C12H12)(η5-C9H7)][BF4]8. Reaction of these bis(1,3-diene) cations with the nucleophiles ‘H–’ and ‘Ph–’ leads to regioselective attack on the exo-η4-1,3-diene moiety. Treatment of 1, 2 and 3 with AgBF4 leads to a one-electron oxidation reaction and formation of the 17-electron species [Mo(C12H13)(η-C5H5)][BF4]10, [Mo(C14H17)(η-C5H5)][BF4]11, and [Mo(C12H13)(η5-C9H7)[BF4]12. A single crystal X-ray diffraction study on 11 indicates the absence of agostic Mo(µ-H)C interactions, the radical cation being best described as a carbon-centred radical η2,η4-bonded to a 16-electron cationic molybdenum centre. Finally, the protonation of 1–4 has been studied, being shown to afford cationic species which adopt different structures in the solid state and in solution. An X-ray crystallographic study on [Mo(η6-C12H13)(µMo,C-H)(η5-C9H7)][CF3SO3], which is formed on reaction of 3 with CF3SO3H, established the presence of an agostic Mo(µ-H)C interaction between a carbon–hydrogen bond β to an alkene moiety, representing an arrested 1,3-hydrogen shift of the type postulated in the initial stage of a metal-assisted isomerisation of an alkene.

Half-sandwich complexes with intramolecular amino group coordination: synthesis and structure of cationic molybdenum dienyl complexes

A half-sandwich cationic molybdenum dienyl complex with intramolecular amino group coordination was obtained from η 5-C 5H 4CH 2CH 2N(CH 3) 2Mo(CO) 2(η 3-C 6H 9) via hydride abstraction followed by CO extrusion. It crystallized as an orange monoclinic compound with a = 10.4867(14), b = 14.843(3), c = 11.882(3) Å, β = 94.057(15)°. The cyclohexadienyl ligand is shown as boat conformation. A second bidentate complex was isolated. Spectroscopic and elemental analysis data support the demethylation product of [η 5-C 5H 4CH 2CH 2 NH(CH 3)M o(CO)( η 3-C 6H 8)] + PF 6 −.

Structural properties of cationic molybdenum and tungsten allyl derivatives

Cationic allyldicarbonyl derivatives of molybdenum and tungsten of the types [M(CO) 2(η 3-allyl)(L 3)PF 6 (M = W, allyl = C 3H 5 or 2-MeC 3H 4, L 3=bis(2-pyridylmethyl)amine, bpma) and [M(CO) 2(η 3-allyl)(L 4)]PF 6 (M = Mo or W, allyl = C 3H 5 or 2-MeC 3H 4, L4 = tris(2-pyridylmethyl)amine, tpma) have been prepared, and their isomerism and dynamic behaviour in solution examined. In the solid state, [W(CO) 2(η 3-C 3H 5)(bpma)]PF 6 ( 1a) exhibits an unsymmetric, and [Mo(CO) 2(η 3-C 3H 5)(tpma)]PF 6 ( 3) a symmetric, orientation of the N-donor set, which comprises two pyridyl rings and the central, exocyclic N of each ligand, with respect to the π-allyl group. The third bipyridyl ring of tpma in the latter complex is orientated away from the metal centre in the solid, but undergoes rapid exchange with N-donors within the coordination sphere at elevated temperatures in solution. Neither of the 2-MeC 3H 4 analogues of 3 are dynamic under similar conditions, whereas the 2-MeC 3H 4 analogue of 1 undergoes a facile trigonal twist rearrangement.

Synthese und stereokontrollierte funktionalisierung von hydridotrispyrazolylborat-molybdän-dien-komplexen

The synthesis of the molybdenum allyl complexes Tp★MO(CO)2(η 3crotyl) ( 2), TpMo(CO) 2(η 3-cyclohexenyl) ( 3a), Tp★Mo(CO) 2(η 3-cyclohexenyl) ( 3b), TpMo(CO) 2(η 3-cycloheptenyl) ( 4) and Tp★MO(CO) 2(η 3-cyclooctenyl) ( 5) is described. The cyclic complexes 3 and 4 are converted to the cationic molybdenum then complexes [TpMo(CO) 2(η 4-cyclohexadien))] + PF 6 − ( 7) upon treatment with Ph 3CPF 6. Complexes 6 and 7 react stereoselectively from the non-metal side with a braod range of nucleophiles. The crystal structure data analysis of 4 is discussed.

Synthesis, crystal structure, electrochemistry and molecular-orbital analysis of the piano-stool dimer [Mo2(η-C5H5)2(CO)4(NC5H4PPh2-2)2

The addition of 2-(diphenylphosphino)pyridine (NC5H4PPh2-2) to an in situ prepared m-xylene solution of [Mo2(η-C5H5)2(CO)4](molar ratio 2 : 1), at room temperature, yields the complex [Mo2(η-C5H5)2(CO)4(NC5H4PPh2-2)2]1. Compound 1 is easily converted into the cationic molybdenum(II) mononuclear complex [Mo(η-C5H5)(CO)3(NC5H4PPh2-2)]PF62 by reaction with AgPF6. Reduction of 1 with Na or Na/Hg, in tetrahydrofuran, affords an air-sensitive solution containing Na[Mo(η-C5H5)(CO)2(NC5H4PPh2-2)]3, together with minor products. Electrochemical measurements show that 1 undergoes a reversible one-electron oxidation followed by relatively slow decomposition of the electrogenerated species. The molecular structure of the diethyl ether solvate of 1 was determined by X-ray diffraction methods: monoclinic, space group P21/c, with a= 13.218(4), b= 19.485(6), c= 11.019(4)A, β= 110.10(2)° and Z= 2. The centrosymmetric complex 1 is a typical piano-stool dimer in which two units share the leg coinciding with the Mo–Mo vector. Similarly to other compounds of this type, the M–M separation is quite long [Mo–Mo 3.276(3)A], ca. 0.5 A longer than the sum of the metal radii. The evidence for the single metal–metal bond (predicted by counting rules) and its role in providing the system's stability is discussed in terms of qualitative molecular orbital theory. The extended-Huckel method used appears sufficiently reliable as the total electronic energy minimizes for an intermetal separation close to the experimental one. The loss of σ bonding, on elongating Mo–Mo, is counterbalanced by the diminished repulsion between metal lone pairs (filled xy orbitals), thus the intermetallic distance is an evident compromise between attractive and repulsive electronic forces. Steric factors may not be so important. The theoretical implications for the eventual homolytic cleavage of the dimer are also underlined. A rationale is provided for the effects that follow the removal of one electron from the system.

Some reactions of cationic 16-electron molybdenum mononitrosyl complexes with phenols and arylamines

The complex [Mo(NO)LCl2]PF6(L =N,N′,N″-trimethyl-1,4,7-triazacyclononane) reacts with methanol to give [Mo(NO)L(Cl)(OMe)]PF6 but the reaction with 4-ferrocenylphenol results in reduction rather than phenoxide formation. The complex [Mo(NO)LBr2]PF6 reacts with 4-amino-2-methyl-4′-ferro-cenylazobenzene to give a bimetallic complex containing a seven-co-ordinate paramagnetic molybdenum centre (µeff= 3.13).

Half-sandwich complex with intramolecular amino group coordination: Synthesis of molybdenum iodide complexes

A half-sandwich molybdenum iodide complex with an intramolecular amino group coordination was obtained by irradiation of η 5-C 5H 4CH 2CH 2N(CH 3) 2Mo(CO) 3I. It crystallized as a violet triclinic, a = 8.0910(9), b = 13.4336(18), c = 14.3033(9) Å, α = 116.655(9) β = 90.813(7), and γ = 104.715(10)°. There are two essentially similar independent molecules within the unit cell. The geometry of the pseudo-square pyramidal is shown as cis orientation of the two carbonyl groups. Iodide abstraction by a silver ion generated a cationic molybdenum complex. Replacing the dimethylamino group with methyl α indicated a 2.5: 1 diastereoselectivity ratio.

Some reactions of transition metal amides and alkoxides with coordinated dienes; X-ray crystal structure of (η5-C5H5)2Zr(NHPh)(OSO2CF3)

Cationic molybdenum diene complexes undergo nucleophilic attack by both early transition metal amides and late transition metal alkoxides to give π-allyl complexes.

ChemInform Abstract: Reactivity of Cationic Molybdenum(II) Complexes. Part 4. Isolation and Crystal Structure Determination of cis‐(Mo(CO)2(η‐C5Me5)(PPh3)(N3)) and cis‐(Mo(CO)2(η‐C5Me5)(PPh3)(NCO)).

AbstractThe complex (I) reacts with NaN3 (II) by CO substitution and via nucleophilic attack of N3‐ on a coordinated CO to give a mixture of the cis complexes (III) and (IV), which are separated as pure products by column chromatography.

.eta.4-s-trans-1,3-Dienes as ligands for cationic molybdenum centers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT.eta.4-s-trans-1,3-Dienes as ligands for cationic molybdenum centersStephen A. Benyunes, Michael Green, and Michael J. GrimshireCite this: Organometallics 1989, 8, 9, 2268–2270Publication Date (Print):September 1, 1989Publication History Published online1 May 2002Published inissue 1 September 1989https://doi.org/10.1021/om00111a027RIGHTS & PERMISSIONSArticle Views36Altmetric-Citations28LEARN 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 (450 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: Reaction of Molybdenum Complexes Containing Phosphite with Boron Trihalides. Formation of Cationic Molybdenum Phosphenium Complexes.

AbstractThe Mo fac‐complexes (I) containing a phosphite ligand react with two equiv. BF3·OEt2 to afford mono OR/F exchange products, the fac‐complexes (II).