[W4(O)2)(O-i-Pr)8]2 an unusual octanuclear oxo-alkoxide cluster of tungsten

From the reaction between W₄(p-tolyl)₂(O-i-Pr)₁₀ and H₂, in hydrocarbon solvents, the compound [W₄(O)₂(O-i-Pr)₈]₂, 1, has been isolated in ca. 25% yield. Formation of 1 is traced to the decomposition of a compound of formula [W₄O-i-Pr)₁₀] _n , which has been characterized only by¹H NMR spectroscopy. The latter is formed by the stepwise hydrogenolysis of W₄(p-tolyl)₂(O-i-Pr)₁₀ + H₂ W₄(H)(p-tolyl)(O-i-Pr)₁₀ + toluene; W₄(H)(p-tolyl)(O-i-Pr)₁₀ [W₄(O-i-Pr)₁₀] _n + toluene. In the presence of a small amount of H₂O₂ the previously characterized compound W₄(O)(O-i-Pr)₁₀, 2, is formed. The structure of 1 consists of two pseudo W₄ tetrahedra linked through the agency of a pair of alkoxide bridges that bind two tungsten atoms that in turn cap triangles, W₃(O)₂(O-i-Pr)₇, of tungsten atoms. At –176°C the cell dimensions werea=12.600(3),b=14.722(3),c=12.585(2),=119.77(1),Z=1, andd _calcd = 2.240 g cm^–3 in the space group P1¯. The W-W distances within these triangles are ca. 2.9 Å whereas the capping W-W atom distances are ca. 2.5 Å. The¹H NMR spectrum of 1 in benzene-d₆ is consistent with the maintenance of the solid-state structure in solution.     

The structure of Mo4Cl8(PEt3)4: How unrecognized disorder previously reduced the quality of the refinement

The preparation and structure of the title compound were reported several years ago by McCarly and co-workers ((1978).J. Am. Chem. Soc. 100, 7900). Curiously, it was reported that refinement of the structure converged at exceptionally high figures of merit (R=0.126;R _w =0.158), but no reason was given. In view of a recent observation in this laboratory (Chen and Cotton (1991).J. Am. Chem. Soc. 113, 5857) that a similar type of compound, [Re₄Cl₈(-O)₂(-OMe)₂]^2– exhibited a subtle but elegant disorder, we reexamined the crystal structure of the title compound. It is found to have 92% of the Mo₄ rectangles in one orientation (the only one previously included in the refinement) and 8% in an orientation perpendicular to the main one. In both orientations the ligand positions are approximately the same. The figures of merit are nowR=0.041;R _w =0.064. The three structure parameters previously reported are now only slightly different: Mo-Mo=2.210(1) vs. 2.211(3) Å; Mo-Mo'=2.897(1) vs. 2.901(2) Å; angle Mo-Cl_b-Mo=74.2[8]° vs. 74.4(2)°. We report here the complete structure.     

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.     

Überschreitungen der konventionellen Zahl von Clusterelektronen in Metallhalogeniden des M6X12‐Typs: W6Cl18, (Me4N)2[W6Cl18] und Cs2[W6Cl18]

Beyond the Conventional Number of Electrons in M₆X₁₂ Type Metal Halide Clusters: W₆Cl₁₈, (Me₄N)₂[W₆Cl₁₈], and Cs₂[W₆Cl₁₈] Black octahedral single crystals of W₆Cl₁₈ were obtained by reducing WCl₄ with graphite in a silica tube at 600 °C. The single crystal structure refinement (space group R 3¯, Z = 3, a = b = 1498.9(1) pm, c = 845.47(5) pm) yielded the W₆Cl₁₈ structure, already reported on the basis of X‐ray powder data. (Me₄N)₂[W₆Cl₁₈] and Cs₂[W₆Cl₁₈] were obtained from methanolic solutions of W₆Cl₁₈ with Me₄NCl and CsCl, respectively. The structure of (Me₄N)₂[W₆Cl₁₈] was refined from X‐ray single crystal data (space group P 3¯m1, Z = 1, a = b = 1079.3(1) pm, c = 857.81(7) pm), and the structure of Cs₂[W₆Cl₁₈] was refined from X‐ray powder data (space group P 3¯, Z = 1, a = b = 932.10(7) pm, c = 853.02(6) pm). The crystal structure of W₆Cl₁₈ contains molecular W₆Cl₁₈ units arranged as in a cubic closest packing. The structures of (Me₄N)₂[W₆Cl₁₈] and Cs₂[W₆Cl₁₈] can be considered as derivatives of the W₆Cl₁₈ structure in which 2/3 of the W₆Cl₁₈ molecules are substituted by Me₄N⁺ ions and Cs⁺ ions, respectively. The conventional number of 16 electrons/cluster is exceeded in these compounds, with 18 electrons for W₆Cl₁₈ and 20 electrons for (Me₄N)₂[W₆Cl₁₈] and Cs₂[W₆Cl₁₈]. Cs₂[W₆Cl₁₈] exhibits temperature independent paramagnetic behaviour.     

Synthesis and crystal structure of the octahedral cluster complex [Th(DMSO)8Cl][Re6Se7Cl7]

A cluster complex of the composition [Th(DMSO)₈Cl][Re₆Se₇Cl₇] has been obtained by interaction of ThCl₄ solution in DMSO with a water solution of K₃[Re₆Se₇Cl₇] and KCl. The compound crystallizes in the rhombic space group Pbcm with unit cell parameters a = 12.262(2) Å, b = 19.653(6) Å, c = 23.603(6) Å, V = 5688(2) ų, Z = 4, d _calc = 3.282 g/cm³. The structure is built from centrosymmetric cluster anions [Re₆Se₇Cl₇]^3? and complex cations [Th(DMSO)₈Cl]³⁺ possessing mirror-plane symmetry, half of the DMSO ligands being doubly disordered.     

Synthesis and crystal and molecular structure of Mo4O(OCH2But)10(py): A 12-electron butterfly cluster

From the reaction between Mo₂(OCH₂Bu^t)₆ and water (1/2 equiv) in toluene solution in the presence of pyridine the oxo-alkoxide tetranuclear cluster Mo₄O(OCH₂Bu^t)₁₀(py) has been isolated as a dark crystalline compound. Crystal data at –121°C:a=24.762(12) Å,b=24.799(9) Å,c=23.021(9) Å,Z=8,d _caled=1.27 g cm^–3 in space group 14/m. The compound contains a Mo₄ butterfly with a hinge angle of 137° between the two Mo₃ triangles. The molecule has a crystallographically-imposed mirror plane of symmetry that contains the wing-tip Mo atoms. One wing-tip Mo atom is in an octahedral environment being bonded to two terminal and two-bridging OR ligands, and one pyridine ligand that is trans to a ₃-oxo bridge. The other Mo atoms are each coordinated to only four oxygen atoms. The backbone Mo atoms have one terminal and two bridging OR ligands and form one bond each to the ₃-oxo group. The other wing-tip Mo atom is coordinated to two terminal and two bridging OR groups. The five Mo-Mo distances span the range 2.43–2.59 Å. The¹H and¹³C{¹H} NMR spectra in benzene-d₆ are consistent with the presence of this structure in solution. The present results are compared to earlier findings for 12-electron alkoxide clusters of Mo and W.     

Polycations Stabilised by Borosulfates: [Au3Cl4][B(S2O7)2] and the One-Dimensional Metal [Au2Cl4][B(S2O7)2](SO3)

(SO₄)-rich silicate analogue borosulfates are able to stabilise cationic cluster-like and chain-like aggregates. Single crystals of [Au₃Cl₄][B(S₂O₇)₂] and [Au₂Cl₄][B(S₂O₇)₂](SO₃) were obtained by solvothermal reaction with SO₃, and the electronic properties were investigated by means of density functional theory–based calculations. [Au₃Cl₄][B(S₂O₇)₂] exhibits a cluster-like cation, and the cationic gold-chloride strands in [Au₂Cl₄][B(S₂O₇)₂](SO₃) are found to resemble one-dimensional metallic wires. This is confirmed by polarisation microscopy.     

[W(NPPh3)4]Cl2 — Ein Phosphaniminato-Komplex mit einem Wolfram-Dikation

[W(NPPh₃)₄]Cl₂ — a Phosphoraneiminato Complex with a Dication of Tungsten The title compound has been prepared by the reaction of Me₃SiNPPh₃ with WNCl₃ and WO₂Cl₂, respectively, in acetonitrile, forming colourless crystals, which were characterized by IR spectroscopy and by an X-ray structure determination. Space group P2₁/n, Z = 4, 4 424 observed unique reflections, R = 0.045. Lattice dimensions at 20°C: a = 1 206.5(2), b = 2 225.3(2), c = 2 421.0(3) pm, β = 101.09(1)°. In the dication [W(NPPh₃)₄]²⁺ the tungsten atom is surrounded in a tetrahedral fashion by the four nitrogen atoms of the phosphoraneiminato ligands. The bond lengths WN and PN correspond with double bonds.     

Bis(N‐acetyltriethylphosphaniminium)‐tetraacetato‐dichloro‐dicuprat(II), [MeC(O)N(H)PEt3]2[Cu2(O2C–Me)4Cl2]

Bis(N‐acetyltriethylphosphaneiminium)‐tetraacetato‐dichloro‐dicuprate(II), [MeC(O)N(H)PEt₃]₂[Cu₂(O₂C–Me)₄Cl₂] The title compound has been prepared by the reaction of Me₃SiNPEt₃ with [Cu₂(O₂C–Me)₄] and MeC(O)Cl in dichloromethane solution to give colourless crystals which include four molecules CH₂Cl₂ per formula unit. The complex is characterized by IR spectroscopy and by a crystal structure determination. [MeC(O)N(H)PEt₃]₂[Cu₂(O₂C–Me)₄Cl₂] · 4 CH₂Cl₂: Space group P2₁/n, Z = 2, lattice dimensions at –70 °C: a = 794.1(1), b = 2356.9(6), c = 1327.3(2) pm; β = 91.00(1)°; R₁ = 0.0597. The structure consists of N‐acetyltriethylphosphaneiminium cations and dianions [Cu₂(O₂C–Me)₄Cl₂]^2– which form an iontriple with N–H…Cl hydrogen bridges.     

Thiocyanate Compounds of [Nb6Cl12]2+: The structure of A4[Nb6Cl12(NCS)6](H2O)4 (A = K,Rb, NH4)

New compounds of the general formula A₄[Nb₆Cl₁₂(NCS)₆](H₂O)₄ (A = K, Rb, NH₄) were synthesized from Nb₆Cl₁₄ and ASCN in aqueous solutions. X-ray structure refinements were performed on single-crystal data of the three compounds. They are isotypic and crystallize with the space group P1 (Z = 1) and the lattice parameters: a = 877.9(3) pm, b = 1176.6(3) pm, c = 1187.0(3) pm, α = 114.29(1)°, β = 98.96(2)°, γ = 100.91(2)° for K₄[Nb₆Cl₁₂(NCS)₆](H₂O)₄ ( 1 ); a = 887.6(3) pm, b = 1184.0(4) pm, c = 1195.4(4) pm, α = 114.95(2)°, β = 98.84(2)°, γ = 101.31(2)° for Rb₄[Nb₆Cl₁₂(NCS)₆](H₂O)₄ ( 2 ) and a = 886.0(4) pm, b = 1181.1(6) pm, c = 1183.9(6) pm, α = 114.49(2)°, β = 99.48(3)°, γ = 101.53(1)° for (NH₄)₄[Nb₆Cl₁₂(NCS)₆](H₂O)₄ ( 3 ). Each centrosymmetric [Nb₆Cl₁₂(NCS)₆]^4? ion of the isotypic compounds contains six terminal thiocyanate groups being bound to the corners of the octahedral niobium cluster through the nitrogen atoms (d_{Nb? N} = 221.5(6)–224.3(6) pm, bond angles Nb? N? C 168.6(5)–176.4(6)°). The [Nb₆Cl₁₂(NCS)₆]^4? ions are linked via A? S and A? Cl interactions with the A cations. Half of the cations occur to be disordered along two crystallographic sites.     

A new route to prepare the mixed oxo-ethylidyne-capped trinuclear tungsten(IV) cluster and the crystal structure of H2Na3[W3O(CCH3)-(O2CCH3)6(H2O)3][H2W12O40]·13.5H2O

The synthesis and the structural characterization of the title compound H₂Na₃[W₃O(CCH₃)-(O₂CCH₃)₆(H₂O)₃][H₂W₁₂O₄₀]·13.5H₂O are described. It is known that the mixed oxo-ethylidynecapped tritungsten cluster can be obtained by Zn dust reduction of Na₂WO₄·2H₂O in acetic anhydride. The title compound has been characterized by X-ray diffraction, UV/VIS and ¹H NMR spectra. The tungsten atoms in the cluster cation and anion are in the oxidation states of W(IV) and W(VI) respectively. The crystal is rhombohedral with the space group R32, a = 17.058 (3)Å, c = 49.665 (9)Å, γ=120°, V=12516(9)ų, Z=6, final R = 0.037 for 2071 reflections with I ≥3σ (I). Both the cluster cation and anion have a C₃ symmetry. The important interatomic distances in angstroms for the cluster cation are: W—W, 2.730(2); W—μ₃?O, 2.00; W—O (carboxy1), 2.12; W—O_t 2.18 (2).     

Acetic acid induced self-assembly of supramolecular compounds [Et4N]3[(WS4Cu2)2(mu-CN)3].2MeCN and [PPh4][WS4Cu3(mu-CN)2].MeCN from preformed clusters [A]2[WS4(CuCN)2] (A = Et4N, PPh4)

Reactions of two preformed trinuclear W/Cu/S clusters, [A](2)[WS(4)(CuCN)(2)] (1: A = Et(4)N; 2: A = PPh(4)), with different concentrations of acetic acid in MeCN generate two interesting 2D polymeric clusters [Et(4)N](3)[(WS(4)Cu(2))(2)(mu-CN)(3)].2MeCN (3), and [PPh(4)][WS(4)Cu(3)(mu-CN)(2)].MeCN (4), respectively. Compound 4 can also be readily obtained in a high yield from the reaction of 2 with equimolar [Cu(MeCN)(4)]PF(6) in MeCN. These compounds have been characterized by elemental analysis, IR spectra, thermal analysis, and single-crystal X-ray diffraction. An X-ray analysis reveals that compound 3 retains the WS(4)Cu(2) cluster core, which serves as a 3-connecting node to link equivalent nodes via single cyanide bridges, forming an anionic 2D (6,3) net. Compound 4 consists of a T-shaped WS(4)Cu(3) core, which also acts as a 3-connecting node, with links to 3 equivalent clusters either through single or double cyanide bridges, affording a different anionic 2D (6,3) network. The acetic acid induced aggregation of 3 and 4 from the two cluster precursors 1 and 2 suggests that this simple synthetic strategy is likely to be applicable to many related systems.     

Mixed Valence Tungsten(IV,V) Compounds with Layered Structures (Part II)): Synthesis and Crystal Structures of Cu1−x[W2O2Cl6] and Cu1−x[W4O4Cl10]

The reaction of CuCl with WOCl₃ at 400 °C leads to a mixture of Cu_1?x[W₂O₂Cl₆] ( 1 ) and Cu_1?x[W₄O₄Cl₁₀] ( 2 ) in form of black lustrous needles. Both compounds crystallize in space group C2/m with a = 12.7832(5) Å, b = 3.7656(2) Å, c = 10.7362(3) Å, β = 119.169(2)° for 1 and a = 12.8367(19) Å, b = 3.7715(7) Å, c = 15.955(3) Å, β = 102.736(5)° for 2 . The structures are made up of WO₂Cl₄ octahedra. In the case of 1 two octahedra are edge‐sharing via chlorine atoms to form pairs which are linked via the trans‐positioned oxygen atoms to form infinite double strands . In the structure of 2 two of these double strands are condensed via terminal chlorine atoms to form quadruple strands . Like for all members of the M_x[W₂O₂X₆] structure family (X = Cl, Br) nonstochiometry with respect to the cations M was observed. The copper content of 1 and 2 was derived from the site occupation factors of the respective structure refinements. For several crystals examined the copper content varied between x = 0.27 and 0.17 for 1 and x = 0.04 for 2 . In both structures the oxochlorotungstate strands are negatively charged and connected to layers by the monovalent copper ions, which are tetrahedrally coordinated by the non‐bridging chlorine atoms of the strands. The structure models imply disorder of the Cu⁺ ions over closely neighboured sites.     

Neutron diffraction study of [H(4)Co(4)(C(5)Me(4)Et)(4)], a tetrahedral metal cluster complex with four face-bridging hydride ligands

A single-crystal neutron diffraction analysis of the cluster complex [H(4)Co(4)(C(5)Me(4)Et)(4)] was carried out on the new quasi-Laue diffractometer VIVALDI at the Institut Laue-Langevin. The structure consists of four face-bridging hydrides attached to a tetrahedral cobalt metal core. Average distances and angles in the core of the molecule are as follows: Co-Co = 2.571(8), Co-C = 2.158(6), Co-H = 1.749(7), H.H = 2.366(9) A; Co-H-Co = 94.6(3), H-Co-H = 85.1(3) degrees. The hydride ligands are located off the Co-Co-Co planes by an average distance of 0.923(8) A. It is suggested that the dimensions of the HCo(3) fragments found in this molecule provide reasonable estimates for analogous distances and angles associated with chemisorbed H atoms situated on the 3-fold hollows of a cobalt surface. Crystallographic details: space group P2(1)/a (monoclinic); a = 21.979(2), b = 10.924(1), c = 34.406(2) A; beta = 90.81(1) degrees; Z = 8. Final agreement factor: R(F) = 0.099 for 3779 reflections [I > 2sigma(I)] collected at 20 K.     

SYNTHESIS AND X-RAY CRYSTAL STRUCTURE OF THE CHLORIDE-BRIDGED FACE-SHARING BIOCTAHEDRAL DIRHODIUM COMPLEX [HP-i-Pr3][Rh2Cl7(P-i-Pr3)2]

Abstract

The reaction of an ethanolic suspension of [NH₄]₃RhCl₆] and P-i′-Pr₃, in the presence of concentrated HC1, for 24h, gives [HP-i-Pr₃][Rh₂Cl₇(P-i-Pr₃)₂], 1, in 18.5% yeild and a small amount of Rh(H)(Cl)₂(P-i-Pr₃)₂, 2. The dinuclear complex 1 was characterized by elemental analyses, IR, ¹H, ³¹P NMR spectroscopy, and single crystal X-ray analysis. However, when the above reaction is continued for 48 h one obtains only 2, in good yield. It is proposed that complex 1 is a reaction intermediate leading to 2. Crystallographic data for 1 (at 298 K) are a = 15.944(3), b = 22.413(4), c= 11.500(4) Å, space group Pna2_x (Z = 4).     

Oxo-Phosphaniminato-Komplexe von Molybdän und Wolfram. Die Kristallstrukturen von [Mo(O)2(NPPh3)2] und [WO(NPPh3)3]2[W6O19]

Oxo-phosphoraneiminato Complexes of Molybdenum and Tungsten. Crystal Structures of [Mo(O)₂(NPPh₃)₂] and [WO(NPPh₃)₃]₂[W₆O₁₉] The dioxo-phosphoraneiminato complexes [Mo(O)₂(NPPh₃)₂] ( 1 ) and [W(O)₂(NPPh₃)₂] ( 2 ) originate from hydrolysis of the nitrido complexes [MN(NPPh₃)₃] (M = Mo, W). They form colourless crystals, which are characterized by IR and NMR spectroscopy as well as by mass spectrometry. According to the crystal structure analysis of 1 (space group Fdd2, Z = 8; lattice dimensions at –83 °C: a = 1953.3(1), b = 3275.8(3), c = 953.4(1) pm) there are monomeric molecules with tetrahedrally coordinated molybdenum atoms. The distances MoO of 171.2 pm and MoN of 185.9 pm correspond to double bonds. In dichloromethane solution 2 undergoes further hydrolysis with colourless crystals of [WO(NPPh₃)₃]₂[W₆O₁₉] ( 3 ) originating, which are characterized crystallographically (space group Pbcn, Z = 4; lattice dimensions at –50 °C: a = 3225.1(6), b = 1803.6(3), c = 1811.9(3) pm). 3 consists of cations [WO(NPPh₃)₃]⁺ with tetrahedrally coordinated tungsten atoms and of the known [W₆O₁₉]^2– anions. The tungsten atoms of the cations show distances WO of 171.8 pm and WN of 182 pm which correspond to double bonds as in 1 .     

SYNTHESIS AND STRUCTURE OF A NOVEL MONONUCLEAR TUNGSTEN (VI) CITRATO COMPLEX, (NH4)3[Li(H2O)3WO3(C6 H4O7)]

Abstract

The first mononuclear tungsten-citrato complex, (NH₄)₃[Li (H₂O)₃WO₃(C₆H₄O₇)] (1), has been prepared by the reaction of ammonium tetrathio tungstate and lithium citrate in CH₃OH-H₂O solution at pH 8.2. There are two crystallographically independent anions in the asymmetric crystallographic unit. The crystal structure of the title compound (triclinic, space group P1, a = 6.901(1), b = 15.136(3), c = 16.107(3) Å, α = 75.85(3), β = 89.89(3), γ = 89.97(3), V = 1631.4(6) ų, R = 0.068, R _W = 0.1674 for 3878 reflections with I > 2σ(I)), reveals that in the compound a tungsten atom is coordinated to a fully deprotonated citrate as a tridentate ligand and three terminal oxygen atoms to form a distorted coordination octahedron.