Reactions of molybdenum(III) with macrocyclic polythiaethers

Reactions of MoCl₃(THF)₃ and MoCl₃(PrCN)₃ with the macrocyclic polythiaethers: 1,4,8,11-tetrathiacyclotetradecane (TTP) and 1,4,7,10,13,16-hexathiacyclooctadecane (HTO) were studied. The type of reaction and the complexes formed depend on reactant concentration and nature of the solvent. The complexes: [MoCl₃(HTO)], [(MoCl₃)₂(HTO)(THF)₃], [MoCl₃(TTP)(THF)] and [MoCl₃(TTP)] in which the macrocyclic polythiaethers are coordinated to the molybdenum through sulphur atoms were isolated. Some new mixed-valence complexes were formed in reactions where a partial change in the molybdenum oxidation state and a cleavage of the macrocyclic ring took place. The following complexes were isolated: [Mo₃Cl₉(PHT)₂(PrCN)]·CH₂Cl₂, [Mo₃Cl₉(PHT)₂(THF)] · CH₂Cl₂, [Mo₂Cl₆ (PHT)] · CH₂Cl₂, [Mo₃Cl₉(TTT)₂(THF)] · CH₂Cl₂, where PHT = 3,6,9,12,15-pentathiaheptadec- 16-ene-1-thiolato(1-) and TTT = 4,7,11-trithiatridec-12-ene-1-thiolato(1-). The complexes were characterized on the basis of elemental analyses, magnetic measurements, IR, ¹H NMR, ¹³C NMR and mass spectra.     

Thiochloroanionen von Molybdän(IV). Die Kristallstruktur von (NEt4)3[Mo3(μ3-S)(μ-S2)3Cl6]Cl · CH2Cl2 Kristallstruktur,EPR-Spektrum und magnetische Eigenschaften von (NEt4)2[Mo2(μ-S2)(μ-Cl)2Cl6]

Thiochloro Anions of Molybdenum (IV). Crystal Structure of (NEt₄)₃[Mo₃(μ₃-S)(μ-S₂)₃Cl₆]Cl μ CH₂Cl₂. Crystal Structure, Magnetic Properties, and EPR-Spectrum of (NEt₄)₂ [Mo₂(μ-S₂)(μ-Cl)₂Cl₆] From molybdenum pentachloride and tetraethylammonium hydrogensulfide in CH₂Cl₂ an insoluble product of composition (NEt₄)₂[Mo₂S₃Cl₉] was obtained along with a brown solution, from which (NEt₄)₂[Mo₂(S₂)Cl₈] was crystallized. The insoluble product and NEt₄Cl react in CH₂Cl₂ to yield, among others, (NEt₄)₃[Mo₃(S)(S₂)₃Cl₆]Cl · CH₂Cl₂. The latter crystallizes in the orthorhombic space group Pnma, a = 2495.8, b = 1501.2, c = 1295.6 pm, Z = 4. According to the crystal structure determination (3070 observed reflexions, R = 0.049) the [Mo₃(S)(S₂)₃Cl₆]^2? ion consists of an Mo₃ triangle with Mo? Mo bonds, each side of the triangle is bridged by disulfido groups and one sulfur atom is capped over the Mo₃ triangle; the single chloride ion is looseley associated to three S atoms. (NEt₄)₂[Mo₂(S₂)Cl₈] also crystallizes in the space group Pnma, a = 1425.6, b = 1129.9, c = 2004.7 pm, Z = 4; structure determination with 1703 observed reflexions, R = 0.061. In the [Mo₂(S₂)Cl₈]^2? ion the Mo atoms are bridged via one disulfido group and two chlorine atoms. There is a Mo? Mo bond, but according to the magnetic properties and the EPR spectrum each Mo atom still possesses one unpaired electron.     

Über die Reaktion von 2,2-Dimethylpropylidinphosphan mit Molybdänpentachlorid; die Kristallstruktur von [Mo2Cl6(α,α′-Dipyridyl)3]

Reaction of 2,2-Dimethylpropylidynephosphine with Molybdenum Pentachloride; Crystal Structure of [Mo₂Cl₆(α,α′-dipyridyl)₃] 2,2-Dimethylpropylidynephosphine and molybdenum pentachloride dissolved in POCl₃ react with oxydation of the phosphorus and reduction of the molybdenum atom to give the alkyne complex [Mo₂Cl₄(μ-Cl)₂(μ-H₉C₄? C?C? C₄H₉)(OPCl₃)₂]. Addition of α,α′-dipyridyl or of methyltriphenylphosphonium chloride in dichloromethane results in a displacement of the ligands POCl₃ and H₉C₄? C?C? C₄H₉ from this complex and in the formation of [Mo₂Cl₆(dipy)₃] or [(H₅C₆? )₃P? CH₃]₃[Mo₂Cl₉]. Besides the latter compound small amounts of [(H₅C₆? )₃P? CH₃]₂[MoCl₆] can be isolated from the reaction mixture. [Mo₂Cl₆(dipy)₃] which has already been prepared by other methods crystallizes in the monoclinic space group P2₁/c with {a = 1612; b = 148; c = 1296 pm; γ 109.3°; Z = 4} at 20°C. As shown by a crystal structure determination the complex is built up from [MoCl₂(dipy)₂]⁺ cations and [MoCl₄(dipy)]^? anions. The molybdenum atoms are both octahedrally surrounded. With average values of 238 and 243 pm the Mo? Cl bond distances in the cation, where a cis-arrangement of the chlorine atoms is observed, and in the anion differ significantly from each other. [Mo₂Cl₆(dipy)₃] which has already been prepared by other methods crystallizes in the monoclinic space group P2₁/c with {a = 1612; b = 148; c = 1296 pm; γ = 109.3°; Z = 4} at 20°C. As shown by a crystal structure determination the complex is built up from [MoCl₂(dipy)₂]⁺ cations and [MoCl₄(dipy)]^? anions. The molybdenum atoms are both octahedrally surrounded. With average values of 238 and 243 pm the Mo? Cl bond distances in the cation, where a cis-arrangement of the chlorine atoms is observed, and in the anion differ significantly from each other.     

Die Reaktion von [Mo6Cl8]X4 mit N-Basen

Reaction of [Mo₆Cl₈]X₄ with N-Bases [Mo₆Cl₈]X₄ (X = Cl, Br, I) in ethanol solution by titration with Ag⁺ showed 4 labil X atoms. The displacement of X^? especially by F^? accelerates the titration decisively. Conductivity measurements in ethanol or acetone showed that [Mo₆Cl₈]X₄ at 25°C behave as weak 1:1-electrolytes. Solutions of [Mo₆Cl₈]X₄ in DMF heated up to 60°C and than lowered to 25°C showed that the compounds in this solvent behave as (potential) strong 2:1-valent electrolytes. From the following compounds the labil halides have been determined by titration with Ag⁺: [Mo₆Cl₈]X₄(Py)₂ (X = Cl, Br), [Mo₆Cl₈]X₄(bipy)₂ (X = Cl, Br, I), [Mo₆Cl₈]X₄(Phenpy)₂ (X = Cl, Br, I), (PyH)₂[Mo₆Cl₈]X₆ (X = Cl, Br); (bipyH)₂[Mo₆Cl₈]I₄Cl₂. Always 4 (respectively 6) labil halides have been observed; exception [Mo₆Cl₈]Cl₄(Py)₂ in acetone (2 labil Cl). Lattice constants and mole volumina for the adducts with pyridin and bipyridin have been determined. The adducts with bipyridin and phenylpyridin are isotypic. Conductivity measurements have been made in different solutions. The decomposition on the thermobalance showed that in [Mo₆Cl₈]Cl₄(Py)₂ the bond of pyridin is weak. The 2 pyridin molecules are evolved at the same time. However [Mo₆Cl₈]I₄(Bipy)₂ loses 1 bipyridin only. (PyH)₂[Mo₆Cl₈]X₆ formed during the first decomposition step the novel compounds (PyH) [Mo₆Cl₈]X₅ (X = Cl, Br). Both compounds are isotypic. They behave in ethanol solution as strong 1:1-valent electrolytes.     

Studies of molybdenum thiolato-complexes. The crystal and molecular structures of two triply bridged Mo(V) dimers, [Bu 4 n N][Mo2O2Cl5(SPh)2] and [Mo2O3(SPh)2(S2CNMe2)2]

Summary The complex [Bu ₄ ⁿ N][Mo₂O₂Cl₅(SPh)₂] has been prepared by reaction of [Bu ₄ ⁿ N][MoO(SPh)₄] with stoichiometric amounts of HCl and characterised by single crystal X-ray structure analysis. The dimer is bridged by two oxo-groups and one chloride and each Mo has pseudo-octahedral co-ordination. The related compound [Mo₂O₃(SPh)₂(S₂CNMe₂)₂] was synthesised by reaction of [MoO₂(S₂CNMe₂)₂] with thiophenol in methanol and has also been characterised crystallographically. In this case the triple-bridge consists of two thiophenolate sulphurs and one oxo-group, each molybdenum having pseudo-octahedral geometry. These structures are compared with other triply-bridged species.     

Interaction of [Mo6Cl14]2− with H2Se: Selective Preparation of [Mo6SeCl13]3−

Reaction of [Mo₆(μ₃-Cl)₈Cl₆]²⁻ with H₂Se, generated in situ from ZnSe and 4 M HCl under hydrothermal conditions lead to the substitution of one or two bridging chlorides, depending on the reagents ratio. With the Mo₆/ZnSe 1:3 molar ratio [Mo₆(μ₃-SeCl₇)Cl₆]³⁻ forms selectively in high yield. Further substitution is more hindered, and even at 1:20 cluster-to-selenide molar ratio a mixture of [Mo₆(μ₃-SeCl₇)Cl₆]³⁻ and [Mo₆(μ₃-Se₂Cl₆)Cl₆]⁴⁻ is formed. The products were characterized by X-ray, Raman spectra and electrospray ionization mass spectrometry.     

Synthesis and structure of a seven electron triangular cluster complex [Mo3S4Cl3(dppe)2(PEt3]

The triangular six-electron cluster complex [Mo₃S₄Cl₄(PEt₃) _x (thf)₅] produced by the excision reaction of Mo₃S₇Cl₄ with triethypholsphine is reduced by magnesium at – 20°C. Subsequent addition of dppe (=1,2-his(diphenylphosphino)ethane) to the reduced species affords a seven-electron triangular cluster complex [Mo₃S₄Cl₃(dppe)₂(PEt₃)]. The complex crystallizes in the space groupCm witha=17.170(6),b-19.878(6),c = 13.289(5) = 121.73(2)°,V = 3858(2) A³, andZ = 2. The structure shows an almost equilateral triangle of three molybdenum atoms capped by a Sulfur atom and bridged by three sulfur atoms. The Mo Mo distances, ranging from 2.804(1) to 2.809(1) A are elongated ca. 0.04 A as compared with lose of a six-electron cluster complex with drape ligands. Two molybdenum atoms have a chlorine and a dppe ligands, and the other molybdenum atom bas a chlorine and a triethylphosphine ligands. The UV-Vis spectrum has a characteristic broad hand centered at 1410 n m, which is not observed for six-electron clusters. The ESR spectrum indicates the presence of an unpaired electron consistent with the formulation of the compound as a seven-electron cluster.Dedicated to Professor fiaxi Lu on the occasion of his 80th birthday.     

Einige Reaktionen mit [Mo6Cl8]Cl4

Some Reactions with [Mo₆Cl₈]Cl₄ The reaction of [Mo₆Cl₈]Cl₄ with different chemical agents has been investigated: The methoxylation depends on the CH₃O^? concentration in CH₃OH. The reaction with HF leads to a partial fluorinated [Mo₆Cl₈] product. With NH₄F (NH₄)₂[Mo₆Cl₈]F₆ in formed, the hydrolysis of which leads to [Mo₆Cl₈]F₃(OH) · 2.5 H₂O. This compound can be decomposed thermically into [Mo₆Cl₈]O₂. [Mo₆Br₈]F₆^2? on hydrolysis leads to [Mo₆Br₈]F₃(OH) · 5 H₂O. With CsF Cs₂[Mo₆Cl₈]F₆ is formed, which by hydrolysis is transformed into [Mo₆Cl₈]F₃(OH) · 2.5 H₂O and possibly to [Mo₆Cl₈]F₄ · xH₂O(?). In reaction of [Mo₆Cl₈]Cl₄ with H₂SO₄ one gets [Mo₆Cl₈](SO₄)₂. Salts e. g. [(C₆H₅)₄As]₂[Mo₆Cl₈](OC₆F₅)₆ and adducts e. g. [Mo₆Cl₈](OC₆F₅)₄ · 2 HMPA are prepared. The compounds have been characterized by X-ray powder-diagramms and by IR-spectra.     

Synthese und Struktur von Mo2NCl8 und Mo3N2Cl11

Synthesis and Crystal Structure of Mo_2<>NCl₈ and Mo₃N₂Cl₁₁ The reaction of MoCl₅ with Cl₃VNCl at 140 °C in a sealed glass ampoule yields air sensitive black crystals of the mixed valent molybdenum(V, VI) nitride chloride, Mo₂NCl₈. It crystallizes in the monoclinic space group P2/c with a = 996.1(1), b = 629.4(1), c = 1780.8(3) pm, β = 101.82(2)°, and Z = 4. The crystal structure consists of dinuclear C₂‐symmetrical units [Cl₂(N≡)Mo(μ₂‐Cl)₃Mo(≡N)Cl₂]^— and [Cl₄Mo(μ₂‐Cl)MoCl₄]⁺, connected in an alternating sequence by asymmetric nitrido bridges Mo≡N‐Mo to form chains. The reaction of Cl₃VNCl with MoCl₃ at 140 °C affords Mo₃N₂Cl₁₁, but for the prolonged reaction period, MoNCl₃ is observed in addition. Mo₃N₂Cl₁₁ can also be obtained from MoNCl₃ and MoCl₅ (2:1) at 140 °C. It forms orthorhombic, black crystals with the space group Pca2₁ and a = 1256.1(1), b = 1001.9(1), c = 1330.10(5) pm, and Z = 4. The structure contains the same dinuclear units [Cl₂(N≡)Mo(μ₂‐Cl)₃Mo(≡N)Cl₂]^— as in Mo₂NCl₈, which in this case are connected with MoCl₄⁺ moieties by asymmetric nitrido bridges Mo≡N‐Mo forming chains. In Mo₂NCl₈ the Mo‐N distances in the nearly linear nitrido bridges are 167.6(2), and 214.8(2) pm, whereas in case of Mo₃N₂Cl₁₁ two sets of Mo‐N distances of 166, 8(4) and 214, 0(4) pm as well as 166, 9(4) and 211, 9(4) pm are observed.     

Coordination of Phenylsulfinate PhSO2— to Mo3MS44+ Clusters (M = Ni,Pd)

Reaction of heterometal cuboidal clusters [Mo₃(MCl)S₄(H₂O)₉]³⁺ (M = Ni, Pd) with PhSO₂Na in aqueous HCl leads to the substitution at Ni or Pd to give the [Mo₃(M(PhSO₂))(H₂O)_9—xCl_x]^(3—x)+species, isolated as supramolecular adducts with cucurbituril (Cuc) [Mo₃(Ni(PhSO₂))S₄Cl_1.17(H₂O)_7.83][Mo₃(Ni(PhSO₂))S₄Cl_2.22(H₂O)_6.78]Cl_2.61 · Cuc · 15H₂O ( 1 ) and [Mo₃(Pd(PhSO₂))S₄Cl_1.12(H₂O)_7.88][Mo₃(Pd(PhSO₂))S₄Cl_2.29(H₂O)_6.71]Cl_2.59 · Cuc · 11H₂O ( 2 ), respectively. Crystal structure of 1 and 2 was determined, revealing that the PhSO₂ is coordinated via its sulfur atom (Ni — S 2.182 Å, Pd — S 2.305 Å). The structure of these isostructural compounds is built from triple aggregates {(cluster)(Cuc)(cluster)} united into zigzag chains via hydrogen bonds between coordinated PhSO₂ and H₂O ligands.     

The electronic structure of the oxygen double-bridged μμ′-dioxo-bis(oxodichloroaquo)dimolybdate (V)-ion by SCCC MO method

Results of SCCC MO calculations for the dimeric oxygen double-bridged [Mo₂O₄Cl₄(H₂O)₂]^2–ion are reported. On the basis of these results the previously reported spectra and magnetic properties may be explained. The strong direct molybdenum — molybdenum interaction in the Mo₂O ₄ ²⁺ core was proved to exist.

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Zusammenfassung Die Ergebnisse von SCCC MO-Rechnungen für das zweikernige Ion [Mo₂O₄Cl₄(H₂O)₂]^2– mit zweifacher Sauerstoffbrücke werden mitgeteilt. Danach können die früher angeführten magnetischen und spektralen Eigenschaften dieses Ions verstanden werden. Die Existenz starker unmittelbarer Molybdän-Molybdän Wechselwirkungen innerhalb des Mo₂O ₄ ²⁺ Kerns wird nachgewiesen.

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Résumé Résultats de calculs SCCCMO pour l'ion dimère Mo₂O₄Cl₄(H₂O) ₂ ^2– . Sur la base de ces résultats les propriétés spectrales et magnétiques précédemment obtenues peuvent être expliquées. L'existence d'une forte interaction directe molybdène-molybdène dans le coeur Mo₂O ₄ ²⁺ est clairement démontrée.

     

Molybdän‐ und Wolfram‐Komplexe mit MNS‐Sequenzen. Die Kristallstrukturen von [MoCl3(N3S2)(1,4‐Dioxan)2] und [Mo2Cl2(μ‐NSN)2(μ‐O)(NCMe3)(OCMe3)2]2

Molybdenum and Tungsten Complexes with MNS Sequences. Crystal Structures of [MoCl₃(N₃S₂)(1,4‐dioxane)₂] and [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ The cyclo‐thiazeno complexes [Cl₃MNSNSN]₂ of molybdenum and tungsten react with 1,4‐dioxane in dichloromethane suspension to give the binuclear donor‐acceptor complexes [μ‐(1,4‐dioxane){MCl₃(N₃S₂)}₂] which are characterized by IR spectroscopy. With excess 1,4‐dioxane the molybdenum compound forms the complex [MoCl₃(N₃S₂)(1,4‐dioxane)₂] in which, according to the crystal structure determination, one of the dioxane molecules coordinates at the molybdenum atom, the other one at one of the sulfur atoms of the cyclo‐thiazeno ring. The μ‐(NSN^2–) complex [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ has been obtained by the reaction of [MoN(OCMe₃)₃] with trithiazyle chloride in carbontetrachloride solution. According to the crystal structure determination this compound forms centrosymmetric dimeric molecules via two of the nitrogen atoms of two of the μ‐(NSN) groups to give a Mo₂N₂ fourmembered ring. [MoCl₃(N₃S₂)(1,4‐dioxane)₂]: Space group P2₁/c, Z = 4, lattice dimensions at –70 °C: a = 1522.9(2); b = 990.3(1); c = 1161.7(1) pm; β = 106.31(1)°, R₁ = 0.0317. [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ · 4 CCl₄: Space group P2₁/c, Z = 2, lattice dimensions at –83 °C: a = 1216.7(1); b = 2193.1(2); c = 1321.8(1) pm; β = 98.23(1)°; R₁ = 0.0507.     

Dithiolylium‐Chlorooxomolybdate(V): Synthese und Kristallstruktur von (C3Cl3S2)[MoOCl4] und (C3Cl3S2)[Mo2O2Cl7]

Dithiolylium Chlorooxomolybdates(V): Synthesis and Crystal Structure of (C₃Cl₃S₂)[MoOCl₄] and (C₃Cl₃S₂)[Mo₂O₂Cl₇] The reaction of 3, 4, 5‐Trichlor‐1, 2‐dithiolylium chloride with MoOCl₃ in dichlormethane under solvothermal conditions at 65 °C simultaneously yields the green tetrachlorooxomolybdate(V) (C₃Cl₃S₂)[MoOCl₄] and the yellow‐brown heptachlorodioxodimolybdate(V) (C₃Cl₃S₂)[Mo₂O₂Cl₇]. The crystal structures of both compounds contain nearly planar (C₃Cl₃S₂)⁺ ions with a S—S bond length of 203 pm. The discrete [MoOCl₄]^— ion in the structure of (C₃Cl₃S₂)[MoOCl₄] has the shape of a square pyramid with the oxygen atom at the apex. The molybdenum atom is displaced by 58 pm from the basal plane towards the oxygen atom. The [Mo₂O₂Cl₇]^— ion in the structure of (C₃Cl₃S₂)[Mo₂O₂Cl₇] has the form of a face‐sharing double octahedron. It is formally composed of a [MoOCl₄]^— ion and a MoOCl₃ molecule connected by one symmetrical and two unsymmetrical chloro bridges. The molybdenum atoms placed in the centers of such connected octahedra are 357 pm apart, indicating no Mo—Mo bond.     

Synthese und Struktur von Mo2NCl7

Synthesis and Structure of Mo₂NCl₇ The reaction of VN with MoCl₅ at 175 °C in a sealed glass ampoule yields the molybdenum(V) nitride chloride Mo₂NCl₇ in form of air sensitive black crystals with the triclinic space group P1¯ and a = 905.7(8); b = 975.4((6); c = 1283.4(8) pm, α = 103.13(4)°; β = 109.83(5)° und γ = 98.58(5)°. The crystal structure is built up from dinuclear units [Mo₂N₂Cl₇]^3— and [Mo₂Cl₇]³⁺, which are connected by asymmetric nitrido bridges to form endless chains. Within both dinuclear units the Mo atoms are bridged by three Cl atoms resulting in a Mo‐Mo distance of 349.2(3) pm in the unit [Mo₂N₂Cl₇]^3—. In case of [Mo₂Cl₇]³⁺, however, a shorter Mo‐Mo distance of 289.4(3) pm is observed, which can be interpreted by a single bond. Correspondingly a reduced magnetic moment of 0.95 B.M. per Mo atom is observed.     

ESR-Untersuchungen an μ-Dichloro-bis[chloro-bis(N,N-diäthyldiselenocarbamato)molybdän(V)]-dichlorid, [Mo2CI4(däsc)4]CI2

EPR-Investigations of α-Dichloro-bis[chloro?bis(N,N?diethyldiselenocarbamato)molybdänum(V)] dichloride, [Mo₂Cl₄(däsc)₄]Cl₂. Preparation and bonding properties of the coordination sphere of [Mo₂Cl₄(däsc)₄]Cl₂ studied by EPR, are reported. The EPR-spectrum at 77°K can be described by an axial symmetric spin-HAMILTONian, the parameters of which are g| = 2.046, g|= 1.996, A| = 53.5 · 10^?4 cm^?1, and A| = 22.8 · 10^?4 cm^?1. No ⁷⁷Se-ligand hyperfine structure could be observed. The very high g-values are explained as being caused by strong ligand spin-orbit interaction, CT-contributions and a high degree of co valency of tho Mo? Se bond. Using an MO-model of the symmetry C_4v, the bonding parameters of the first coordination sphere have been calculated.     

Structural Study and Solution Integrity of Dioxomolybdenum(VI) Complexes with Tridentate Schiff Base and Azole Ligands

Four new molybdenum complexes [Mo^VIO₂(L¹)(Him)] ( 1 ), [Mo^VIO₂(L¹)(3‐MepzH] ( 2 ), [Mo^VIO₂(L²)(3‐MepzH)] ( 3 ), and [(Mo^VIO₂)₂(μ‐L³)(MeOH)₂] ( 4 ) were synthesized and characterized by IR, NMR, ESI‐MS, and single‐crystal structure analysis [H₂L¹ = 2‐(salicylideneamino)‐2‐methyl‐1‐propanol, H₂L² = 2‐(3‐methoxysalicylideneamino)‐2‐methyl‐1‐propanol, H₄L³ = 1, 7‐bis(salicylidene)dihydrazide malonic acid, Him = imidazole and 3‐MepzH = 3‐methylpyrazole]. In all four structures the molybdenum atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base di‐ or tetraanion (L^{1, 2})^2—/(L³)^4— and one oxo group occupying the sites of the equatorial plane. The other oxo group and the azole or methanol molecule occupy the apical sites. In 1—3 two centrosymmetrically related molecules form a hydrogen‐bonded pair through the (azole)N‐H···O(alkoxo) interaction. Additional crystal packing appears to be controlled mostly by π stacking between the aromatic rings of the salicyl moiety. ESI‐MS investigations reveal that the integrity of complexes 1—4 is largely retained in methanol solution. At the same time evidence is provided that di‐ to tetranuclear oligomers of formula [{Mo^VIO₂(L)}_x] and [{Mo^VIO₂(L)}_x(3‐MepzH)] with L = L¹, L², x = 2, 3, 4 are present simultaneously with 2 and 3 in methanol solution, respectively the tetranuclear species [{(Mo^VIO₂)₂(L³)}₂] with 4 .     

Synthese und Kristallstruktur von (PPh4)2[Mo2(S2)2Cl8] · 2 CH3CN und seine topotaktische Umwandlung zu (PPh4)2[Mo2(S2)2Cl8]

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂(S₂)₂Cl₈] · 2 CH₃CN and its Topotactic Transformation to (PPh₄)₂[Mo₂(S₂)₂Cl₈] MoS₂Cl₃ was prepared from molybdenum and S₂Cl₂ at 200 °C. Its reaction with PPh₄Cl in acetonitrile yielded (PPh₄)₂[Mo₂(S₂)₂Cl₈] · 2 CH₃CN. In vacuum or upon warming, it loses the acetronitrile without degradation of the crystals. According to the X-ray crystal structure determinations both compounds, with and without acetonitrile, are triclinic. They contain the same [Cl₄Mo(μ-S₂)₂MoCl₄]^2– ions, in which the Mo atoms are joined by two disulfido groups and an Mo–Mo bond. Details of the crystal packings and their topotactic transformation are given.     

Synthesis and Crystal Structure of Cucurbit[6]uril Adduct of Hydrogen-bonded Cluster Complex [Mo3(μ3-Se)(μ2-O)3(H2O)6Cl3]+

Reaction of [MoOCl₅]²⁻ with in situ generated H₂Se under hydrothermal conditions (4M HCl, 140 °C) leads to reduction of Mo(V) to Mo(IV) with the formation of a triangular cluster Mo₃(μ₃-Se)(μ-O)₃⁴⁺ in high yield. It is present in HCl solutions as aqua chlorocomplex [Mo₃(μ₃-Se)(μ-O)₃(H₂O)₆Cl₃]⁺ which was isolated and structurally characterized as supramolecular adduct with cucurbit[6]uril (CB[6]), {[Mo₃(μ₃-Se)(μ-O)₃(H₂O)₆Cl₃]₂CB[6]}Cl₂·15H₂O. Dedicated to Professor Dieter Fenske on the Occasion of his 65th Birthday     

Synthesis and Structure of a Series of New Molybdenum(VI) Complexes with the Esters of 2‐Mercaptonicotinic Acid

The novel dioxomolybdenum(VI) complexes with methyl ( 1 ), ethyl ( 2 ), n‐propyl ( 3 ), i‐propyl ( 4 ), n‐butyl ( 5 ) and cyclohexyl ( 6 ) ester of 2‐mercaptonicotinic acid have been prepared in the reactions of MoO₂Cl₂ and MoO₂(acac)₂ (acac = 2,4‐pentandionate) with mercaptonicotinic acid in corresponding alcohol. The esterification reaction was catalyzed by Mo^V originated from the reduction of Mo^VI with mercaptonicotinic ‐SH group with simultaneous formation of S–S bond resulting from the condensation of two 2‐mercaptonicotinic molecules. The presence of Mo^V was proved by ESR spectra. The molecular and crystal structures of 1 , 2 , 3 and 4 as well as of the by‐products 1,1′‐dithio‐2,2′‐n‐butylnicotinoate ( 7 ) and tetramethylammonium hexachloromolybdate(V) ( 8 ) have been determined by a X‐ray single crystal diffraction. The complexes 1 – 4 contain MoO₂²⁺ core with octahedral coordination of each molybdenum atom complexed by two 2‐mercaptonicotinato N and S donor atoms.