Tungsten Derivatives Research Articles

Design of a scheelite production pilot plant for the treatment of spent electroless nickel plating solutions in Field Service Solution S.A.S.: an alternative source for tungsten recycling

In this contribution, the design considerations to assemble a pilot-plant for tungsten recovery and further conversion into synthetic scheeliteas raw material, as an eco-friendly improvement for the current electroless nickel process in Field Service Solution (FES) S. A. S., arepresented. This low-cost methodology scale-up aims to provide an alternative treatment for spent electroless nickel solutions (Ni-P-W) asa secondary tungsten source. The plant is projected to treat up to 750 L of industrial waste per week, achieving a maximum scheeliteproduction of 9.1 kg per week. This prototype serves as a model of eco-sustainability in the nickel-plating industry by controlling thedisposal of heavy metals and by facilitating the production of other tungsten derivatives and their feasible reuse in the process.

Scheelite production from spent electroless nickel solutions as an alternative tungsten recycling source

Tungsten, considered a specialty metal, plays a remarkable role in the development of new tools for aerospace, defense, and other trending technological applications. However, due to its high supply risk index, extensive research on alternative sources for recycling has been conducted. In this contribution, the recovery of tungsten from spent electroless nickel solutions as a secondary metal source for this element is described for the first time. Laboratory experimental procedures are presented, involving the acid-promoted tungstite precipitation where the oxidizing properties of nitric acid demonstrated to play a key role in the tungsten oxide product formation. Further reaction with calcium hydroxide allows the rapid isolation of high-purity scheelite (>98%) in good yield. This protocol serves as a model for a tungsten recovery pilot plant scale-up, where other reactions for the preparation of additional tungsten derivatives, employing scheelite as starting material, can be implemented.

Structural elucidation of tungsten compounds containing arylamine, piperazine and morpholine fragments of pyrrole and keto-amine ligands

Various imido tungsten derivatives incorporating bidentate pyrrole–piperazine, pyrrole–morpholine, pyrrole–imine and keto-amine precursors were synthesized. Reacting W(NtBu)2(NHtBu)2 with one equivalent of the pyrrole–phenylpiperazine ligand {C4H3NH-[2-CH2N(CH2CH2)2NPh]} in toluene generated [W(NtBu)2(NHtBu){C4H3N-[2-CH2N(CH2CH2)2NPh]}] (1). Similarly, addition of W(NtBu)2(NHtBu)2 to one equivalent of the pyrrole–morpholine ligand {C4H3NH-[2-CH2N(CH2CH2)2O]} in toluene afforded [W(NtBu)2(NHtBu){C4H3N-[2-CH2N(CH2CH2)2O]}] (2), which was converted to [W(NtBu)2{C4H3N-[2-CH2N(CH2CH2)2O]}]2(μ2-O) (3) in moisture. Reacting the pyrrole–imine ligand {C4H3NH-[2-CHN(C6H3-2,6-iPr2)]} with one equivalent of W(NtBu)2(NHtBu)2 in toluene gave [W(NtBu)2(NHtBu){C4H3N-[2-CHN(C6H3-2,6-iPr2)]}] (4), which was transformed to [W(NtBu)(NHtBu){C4H3N-[2-CHN(C6H3-2,6-iPr2)]}(μ-O)]2 (5) upon absorbing moisture. Furthermore, when one equivalent of {C4H3NH-[2-CHNC2H4N(C2H4)2O]} reacted with W(NtBu)2(NHtBu)2 in toluene, {W(NtBu)2{C4H3N-[2-CHNC2H4N(C2H4)2O]}2} (6) was isolated. The tungsten keto-amine compounds {W(NtBu)2[OCMeCHCMeN(C6H3-2,6-iPr2)]2} (7) and {W(NtBu)2[OCMeCHCMeNCH2CH2N(CH2CH2)2O]2} (8) were obtained by the reaction between W(NtBu)2(NHtBu)2 and two equivalents of the corresponding keto-amine ligands in toluene. All the tungsten derivatives were characterized by 1H and 13C NMR spectroscopy. Single crystal X-ray diffraction analysis revealed that in compounds, 1, 3, 5, 6 and 7, the central W atom belonged to either a distorted trigonal bipyramidal or an octahedral geometrical arrangement. Overall, the influence of the substituted pyrrole and keto-amine bidentate precursors on the imido tungsten derivatives were explored and structurally constructed.

(Pyrazol-1-yl)carbonyl and Ester-Functionalized Bis(pyrazol-1-yl)methide Carbonyl Tungsten Complexes

(3,5-Dimethylpyrazol-1-yl)carbonyl- and n-butoxycarbonyl-functionalized bis(3,5-dimethylpyrazol-1-yl)methide carbonyl tungsten derivatives were unexpectedly formed, together with a bis(3,5-dimethylpyrazol-1-yl)acyl carbonyl tungsten complex, upon sequential treatment of bis(3,5-dimethylpyrazol-1-yl)methane with n-BuLi, tungsten carbonyl, and iodine. The resulting complexes were fully characterized using IR and NMR spectroscopy, and their structures were unambiguously determined by X-ray crystallography.

Synthesis and characterization of tungsten bis-imido complexes containing bi-dentate pyrrole-amine, pyrrole-imine or ketiminate ligands

Three new imido tungsten derivatives containing bi-dentate pyrrole-amine, pyrrole-imine or ketiminate precursor were synthesized and characterized. Reacting W(NtBu)2(NHtBu)2 with two equiv of C4H3NH(2-CH2NHtBu) and C4H3NH(2-CHNCH2Py) in diethyl ether and toluene generates [W(NtBu)2{C4H3N(2-CH2NHtBu)}2] (1) and [W(NtBu)2{C4H3N(2-CHNCH2Py)}2] (2) in good yield. Similarly, while subjecting two equiv of (ArNCMeCHCMeOH) (Ar=2-MeOC6H4) with W(NtBu)2(NHtBu)2 in diethyl ether, affords [W(NtBu)2{OCMeCHCMeNAr}2] (3) in high yield. Single crystal X-ray structure reveals that in all three complexes the 6-coordinate W atoms belong to a distorted octahedral environment.

On the Track to Silica-Supported Tungsten Oxo Metathesis Catalysts: Input from 17O Solid-State NMR

The grafting of an oxo chloro trisalkyl tungsten derivative on silica dehydroxylated at 700 °C was studied by several techniques that showed reaction via W-Cl cleavage, to afford a well-defined precatalyst for alkene metathesis. This was further confirmed by DFT calculations on the grafting process. (17)O labeling of the oxo moiety of a series of related molecular and supported tungsten oxo derivatives was achieved, and the corresponding (17)O MAS NMR spectra were recorded. Combined experimental and theoretical NMR studies yielded information on the local structure of the surface species. Assessment of the (17)O NMR parameters also confirmed the nature of the grafting pathway by ruling out other possible grafting schemes, thanks to highly characteristic anisotropic features arising from the quadrupolar and chemical shift interactions.

Synthesis of carboxylate derivatives of molybdenum and tungsten based on joint insertion of CO2 and PhNCS or N, N′-dicyclohexylcarbodiimide into M-Cl bonds

Reactions of the higher molybdenum and tungsten chlorides with phenyl isothiocyanate or with N, N′-dicyclohexylcarbodiimide and carbon dioxide in dichloroethane are the first to demonstrate the possibility of insertion of carbon dioxide in combination with other heterocumulenes into transition metal-halogen bonds. IR spectroscopy and elemental analysis data show that the reactions result in the attachment of the ligands at the same metal-chlorine bond and the formation of heteromolecular insertion products with the compositions $$\left[ {MoOCl_3 \left\{ {N\left( {Ph} \right)C\left( S \right)} \right\}_2 Nc\left( {Me} \right)Cl} \right]$$ and $$MCl_x \left\{ {OC\left( O \right)\left[ {\left( {Hex} \right)NCN\left( {Hex} \right)} \right]_2 } \right\}Cl,$$ where x = 4 and 5 for the Mo and W derivatives, respectively.

Investigation of induction times, activity, selectivity, interface and mass transport in solvent-free epoxidation by H2O2 and TBHP: a study with organic salts of the [PMo12O40]3− anion

The phosphomolybdate salts Q3[PMo12O40] [Q = tetra-n-butylammonium (TBA), n-butylpyridinium (BP), cetylpyridinium (CP)] have been used as catalysts for the epoxidation of cyclooctene under organic solvent-free conditions, using H2O2 or t-BuOOH (TBHP) in water as oxidants, and compared with the BP salt of the analogous tungsten derivative, (BP)3[PW12O40]. High catalytic activities have been recorded down to very low catalyst loadings (2 ppm). The activity and selectivity depend on the nature of the oxidant and the cation. The dominant process appears to be homogeneous and this rationalizes, together with the evolution of the phase equilibria, the presence of an induction period for the epoxidation by H2O2 and the evolution of the epoxide selectivity. The recovered catalysts are reusable and exhibit equivalent reactivity.

Synthesis and Spectroscopic Studies of Some New Molybdenum, Tungsten, and Ruthenium Carbonyl Derivatives of 2-Hydroxymethylpyridine

Thermal reactions of 2-hydroxymethylpyridine (HMP) with [M(CO)6] in air resulted in formation of the oxo-complexes [M2O6(HMP)2], where M = Mo, 1, or W, 2. The tricarbonyl complex [Ru(CO)3(HMP)], 3, was obtained from the reaction of [Ru3(CO)12] with HMP. In presence of triphenyl phosphine (PPh3), the reaction of HMP with Ru3(CO)12 gave [Ru(CO)2(HMP)(PPh3)], 4. All the complexes were characterized by elemental analysis, mass spectrometry, IR, and NMR spectroscopy. The thermal properties of the complexes were also investigated by thermogravimetry technique.

Synthese, Struktur und Reaktivität von η3‐1,2‐Diphosphaallylkomplexen sowie von [{(η5‐C5H5)(CO)2W–Co(CO)3}{μ‐AsCH(SiMe3)2}(μ‐CO)

AbstractSyntheses, Structure and Reactivity of η3‐1,2‐Diphosphaallyl Complexes and [{(η5‐C5H5)(CO)2W–Co(CO)3}{μ‐AsCH(SiMe3)2}(μ‐CO)]Reaction of ClP=C(SiMe2iPr)2 (3) with Na[Mo(CO)3(η5‐C5H5)] afforded the phosphavinylidene complex [(η5‐C5H5)(CO)2Mo=P=C(SiMe2iPr)2] (4) which in situ was converted into the η1‐1,2‐diphosphaallyl complex [η5‐(C5H5)(CO)2Mo{η3‐tBuPPC(SiMe2iPr)2] (6) by treatment with the phosphaalkene tBuP=C(NMe2)2. The chloroarsanyl complexes [(η5‐C5H5)(CO)3M–As(Cl)CH(SiMe3)2] [where M = Mo (9); M = W (10)] resulted from the reaction of Na[M(CO)3(η5‐C5H5)] (M = Mo, W) with Cl2AsCH(SiMe3)2. The tungsten derivative 10 and Na[Co(CO)4] underwent reaction to give the dinuclear μ‐arsinidene complex [(η5‐C5H5)(CO)2W–Co(CO)3{μ‐AsCH(SiMe3)2}(μ‐CO)] (11). Treatment of [(η5‐C5H5)(CO)2Mo{η3‐tBuPPC(SiMe3)2}] (1) with an equimolar amount of ethereal HBF4 gave rise to a 85/15 mixture of the saline complexes [(η5‐C5H5)(CO)2Mo{η2‐tBu(H)P–P(F)CH(SiMe3)2}]BF4 (18) and [Cp(CO)2Mo{F2PCH(SiMe3)2}(tBuPH2)]BF4 (19) by HF‐addition to the PC bond of the η3‐diphosphaallyl ligand and subsequent protonation (18) and/or scission of the PP bond by the acid (19). Consistently 19 was the sole product when 1 was allowed to react with an excess of ethereal HBF4. The products 6, 9, 10, 11, 18 and 19 were characterized by means of spectroscopy (IR, 1H‐, 13C{1H}‐, 31P{1H}‐NMR, MS). Moreover, the molecular structures of 6, 11 and 18 were determined by X‐ray diffraction analysis.

Dioxo-molybdenum(VI) and -tungsten(VI) BINOL and alkoxide complexes: Synthesis and catalysis in sulfoxidation, olefin epoxidation and hydrosilylation of carbonyl groups

The reaction of MoO 2(mes) 2 with S-H 2BINOL (mes = 2,4,6-Me 3C 6H 2; H 2BINOL = 1,1′-bi-2-naphthol) and (CF 3) 2MeCOH in THF yielded the novel dioxo-molybdenum(VI) complexes MoO 2( S-BINOL)(THF) 2 and MoO 2[OCMe(CF 3) 2] 2(THF), respectively. Similar tungsten derivatives WO 2( S-BINOL)(THF) and WO 2[OCMe(CF 3) 2] 2(THF) have been prepared by the reaction of WO 2Cl 2(DME) with the corresponding lithium salts of BINOL and 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, respectively. Catalytic experiments have shown that MoO 2( S-BINOL)(THF) 2 is an active catalyst in the sulfoxidation of methyl phenyl sulfide and in the epoxidation of cis-cyclooctene with tert-butylhydroperoxide, under mild conditions. The BINOL complex was, however, not found to be enantioselective. In addition, the catalytic activity of the molybdenum species MoO 2( S-BINOL)(THF) 2 and MoO 2[OCMe(CF 3) 2] 2(THF) in the hydrosilylation of carbonyl groups has been explored.

Free and Metal‐Coordinated (N‐Isocyanimino)triphenylphosphorane: X‐ray Structures and Selected Reactions

AbstractAn improved procedure for the synthesis of (N‐isocyanimino)triphenylphosphorane, C≡N–N=PPh3 (3), is described. The X‐ray structure analysis reveals an unusually small N–N=P angle [115.2(2)°] and an N–N bond order of only about 1.5, which indicates considerable C≡N–N––P+ participation and electronically more‐isolated functional groups (CN, P=N) in the isocyanide than, for example, in the isomeric N≡C–N=PPh3 (4) [C–N=P = 123.0(4)°, C–N bond order = 2.0]. In order to gain insight into the stereochemical consequences of metal coordination of 3, an X‐ray structural study of [Cr(CO)5C≡N–N=PPh3] (5) was also undertaken. Surprisingly, the central bond lengths (C–N, N–N) and angles (C–N–N) remain practically unchanged with noticeable coordination effects occurring only at the periphery of 5, with the N–N–P angle [112.3(2)°] further decreased by 15σ, the elongated (by 7σ) P–N bond, the somewhat shortened (by 4σ) P–C(Ph) bonds and even shorter C–H(Ph) bonds on the one side, and the well‐known Cr–C(O)trans contraction on the other. Treatment of 5 or its tungsten derivative with anhydrous Brønstedt and Lewis acids such as CF3COOH, HCl, COS, phosgene or, most efficiently, [PdCl2(1,5‐COD)] causes CN→NC isomerisation to give [M(CO)5N≡C–N=PPh3] [M = Cr (6), W (7)]. In solution, [PdCl2(CNNPh3)2] and Ph3BCNNPPh3 (8) slowly isomerize even without additional acid to give both free and Pd‐coordinated 4 and Ph3BNCNPPh3 (9), respectively. In the presence of catalytic amounts of [PdCl2(1,5‐COD)], 3 is converted into 4 and the dimer Ph3PN–C(CN)=N–NPPh3 (10) in an almost 1:1 ratio. The optimised geometries of the methyl derivatives of 3 and 4, namely Me3P=N–N≡C (3c) and Me3P=N–C≡N (4c), are in excellent agreement with the experimental data; major differences between the isomers (P–N–N angle, N–N bond length) are explained by the higher electronegativity of the isocyano group as compared to the CN substituent, which, in turn, is a better π‐acceptor). The reaction path of the isomerisation of 3 to 4 (3c to 4c) has also been studied computationally and been found to proceed via an [(P)=NA–N≡CA(NA–CA)] cyclic transition state. The overall process is exothermic by 50 kcal mol–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Neue eindimensionale Koordinationspolymere des Typs (NBu4)[(Me3Sn)MO4] (M = Mo, W)

AbstractNovel One‐Dimensional Coordination Polymers of the Type (NBu4)[(Me3Sn)MO4] (M = Mo, W)The reaction of Me3SnBr with (NBu4)2[Mo6O19] and (NBu4)OH in acetonitrile as solvent leads to the formation of (NBu4)[(Me3Sn)MoO4] (3). 3 and the analogous tungsten derivative (NBu4)[(Me3Sn)WO4] (4) are also available by the reaction of [(Me3Sn)2MO4] (M = Mo, W) with (NBu4)OH. 3 crystallizes monoclinic in the space group P21/n with a = 983,8(2), b = 1240,3(2), c = 2172,0(4) pm , β = 99,05(2)° (at 220 K). 4 forms isotypic crystals with a = 989,3(2), b = 1238,7(1), c = 2168,5(4) pm, β = 99,31(2)° (at 220 K). 3 and 4 contain anionic coordination polymers of the type [(Me3Sn)MO4]‐ (M = Mo, W) in which Me3SnO2 bipyramides are linked with MO4 tetrahedra to form chains.

Synthesis of Benzannulated N‐Heterocyclic Carbene Ligands by a Template Synthesis from 2‐Nitrophenyl Isocyanide

The reaction of 2-nitrophenyl isocyanide 2 with [M(CO)5(thf)] (M=Cr, Mo, W) yields the isocyanide complexes [M(CO)5(2)] (3: M=Cr; 4: M=Mo; 5: M=W). Complexes 3-5 react with elemental tin under reduction of the nitro function of the isocyanide ligand to give the complexes with the unstable 2-aminophenyl isocyanide ligand. The coordinated 2-aminophenyl isocyanide ligand in all three complexes reacts spontaneously under intramolecular nucleophilic attack of the primary amine at the isocyanide carbon atom to yield the complexes with the NH,NH-benzimidazol-2-ylidene ligand (6: M=Cr; 7: M=Mo; 8: M=W). An incomplete reduction of the nitro group in 3-5 is observed when hydrazine hydrate is used instead of tin. Here the formation of complexes with a coordinated 2-hydroxylamine-functionalized phenyl isocyanide [(CO)5M-CN-C6H(4-)-2-N(H)-OH] is postulated and this unstable ligand again undergoes intramolecular cyclization to give the NH,NOH-stabilized benzimidazol-2-ylidene complexes 9-11. The tungsten derivative 11 can be allylated stepwise by a deprotonation/alkylation sequence first at the OH and then at the NH position to yield the monoallylated and diallylated species 12 and 13. The molecular structures of 3-5 and 12-13 were established by X-ray crystallography.

Group-6 Imido Activation by a Ring-Strained Alkyne

Treatment of M(NAr)2(Cl)2(DME), where Ar = 2,6-diisopropylphenyl, with cyclooctyne results in the formation of M(C8H12C8H12NAr)(Cl)2(NAr), where M = Mo (1) and W (2). The complexes have metrical and spectroscopic parameters that are most consistent with an alkylidene-imine formulation with some participation by the alkyl-amido resonance form. Thermolysis of metallacycles 1 and 2 generates a pyrrole elimination product, with the tungsten derivative being more thermally stable. In addition, the metallacycle is quite hydrolytically stable. Addition of 50% H2SO4 to a toluene solution of 2 protolytically cleaves all the ligands on the metal except those associated with the metallacycle, which are retained in the oxo product [W(O)(μ-O)(C8H12C8H12NAr)]2 (3). The metallacycles 1−3 will polymerize norbornene in the presence of AlCl3. Compounds 1−3 and the pyrrole were characterized by X-ray diffraction.

New chloro, mu-oxo, and alkyl derivatives of dioxomolybdenum(VI) and -tungsten(VI) complexes chelated with N(2)O tridentate ligands: synthesis and catalytic activities toward olefin epoxidation.

A new series of cis-dioxomolybdenum(VI) complexes MoO(2)(L(n))Cl (n = 1-5) were prepared by the reaction of MoO(2)Cl(2)(DME) (DME = 1,2-dimethoxyethane) with 2-N-(2-pyridylmethyl)aminophenol (HL(1)) or its N-alkyl derivatives (HL(n)) (n = 2-5) in the presence of triethylamine. The new mu-oxo dimolybdenum compounds [MoO(2)(L(n))](2)O (n = 1, 4, 5, 7) were also prepared by treating the corresponding ligand HL(n) with MoO(2)(acac)(2) (acac = acetylacetonate) in warm methanolic solutions or (NH(4))(6)[Mo(7)O(24)].4H(2)O in the presence of dilute HCl. Treatment of MoO(2)(L(1))Cl or [MoO(2)(L(1))](2)O with the Grignard reagent Me(3)SiCH(2)MgCl gave the alkyl compound MoO(2)(L(1))(CH(2)SiMe(3)), which represents the first example of dioxomolybdenum(VI) alkyl complex supported by a N(2)O-type ancillary ligand. The analogous chloro and mu-oxo tungsten derivatives WO(2)(L(n))Cl (n = 6, 7) and [WO(2)(L(n))](2)O (n = 1, 4, 6, 7) were prepared by the reaction of WO(2)Cl(2)(DME) with HL(n) in the presence of triethylamine. Similar to their molybdenum analogues, the tungsten alkyl complexes WO(2)(L(n))(R) (n = 6, 7; R = Me, Et, CH(2)SiMe(3), C(6)H(4)(t)Bu-4) were synthesized by treating WO(2)(L(n))Cl or [WO(2)(L(n))](2)O (n = 6, 7) with the appropriate Grignard reagents. The catalytic properties of selected dioxo-Mo(VI) and -W(VI) chloro and mu-oxo complexes toward epoxidation of styrene by tert-butyl hydroperoxide (TBHP) were also investigated.

Synthesis of new half sandwich tetrachloro derivatives of molybdenum(V) and tungsten(V). X-ray structures of (C 5HPr i4)W(CO) 3(CH 3) and (C 5Et 5)WCl 4

The new synthetic intermediates (Ring)MCl 4 [Ring=C 5HPr i 4 or 4Cp, M=Mo, 2; Ring=C 5Et 5 or VCp, M=W, 4, Ring= 4Cp, M=W, 6] containing sterically protecting cyclopentadienyl ligands have been synthesized. Along the synthetic pathway to 2, it was found that the treatment of [ 4CpMo(CO) 3] − with an aqueous ferric solution according to the well established Manning procedure affords the hydride compound 4CpMo(CO) 3H ( 1) by hydrolysis rather than the expected neutral dimer by oxidation. Compound 1 could be converted, however, to 2 upon oxidation with PhICl 2 in good yields. Compound 4 is shown by a single crystal X-ray analysis to adopt a monomeric four-legged piano stool structure. The precursors to compounds 4 and 6, (Ring)W(CO) 3(CH 3) (Ring= VCp, 3; 4Cp, 5) have also been characterized, including an X-ray structure for 5.

Vanadium and tungsten derivatives as antidiabetic agents: a review of their toxic effects.

Tungstate is an oxyanion that has biological similarities to vanadate. In recent years, a number of studies have shown the antidiabetic effects of oral tungstate in animal models of diabetes. However, because of the tissue accumulation and potential toxicity derived from chronic administration of vanadium and tungsten compounds, the pharmacological use of vanadate or tungstate in the treatment of diabetes is not necessarily exempt from concern. In the context of a potential use in the treatment of human diabetes mellitus, the most relevant toxic effects of vanadium derivatives are reviewed and compared with those reported for tungsten. Hematological and biochemical alterations, loss of body weight, nephrotoxicity, immunotoxicity, reproductive and developmental toxicity, and behavioral toxicity have been reported to occur following exposure to vanadium compounds. Moreover, vanadium also has a mitogenic activity affecting the distribution of chromosomes during mitosis and inducing aneuploidy-related end points. In contrast to vanadate, studies about the toxic effects of tungstate are very scant. Early investigations in cats, rabbits, dogs, mice, and rats showed that tungstate was less toxic than vanadate when given intravenously. Although in vitro investigations showed a direct effect of tungstate on the embryo and fetus of mice at concentrations similar to those causing effects in vivo, information on the potential cellular toxicity of tungstate is particularly scarce. Taking into account the recent interest of tungstate as a new potential oral antidiabetic agent, an exhaustive evaluation of its toxicity in mammals is clearly necessary.

Preparation and crystal structures of new phenoxide derivatives of tungsten(VI) oxytetrachloride

Two oxotungsten(VI) complexes of the type [WOCl 2(OAr) 2] (OAr=OC 6H 3 t Bu-2-Me-6 or OC 6H 2 t Bu-2-Br-4-Me-6) were prepared by the reaction of WOCl 4 with 2 equiv. of phenolic ligand precursors in a refluxing toluene solution. Both compounds form monomeric units, in which the tungsten ion has adopted a square pyramidal coordination geometry with the oxo ligand in the apical position and phenoxide groups bound in a trans orientation.

Synthesis, crystal and molecular structure of a binuclear, double-bridged hexacarbonyl tungsten derivative of 4-pyridyldiphenylphosphane

4-Pyridyldiphenylphosphane is used as a bridging ligand for the first time. The ligand forms a double-bridged bimetallic complex with hexacarbonyl tungsten. Characterization is performed by X-ray analysis and NMR spectroscopy. The crystal structure of the complex shows π-stacking interaction between the pyridyl rings, and structurally the complex is an organometallic analogue of [2.2]-paracyclophanes.