Specific nonbonded interactions in the structures of M3X7 4+ and M3X4 4+ (M=Mo,W; X=O,S, Se) clusters

Specific nonbonded interactions (SNI) involving the chalcogens in the structures of (₃–X)(₂–X₂)₃M₃ ⁴⁺ and (₃–X)(₂–X)₃M₃ ⁴⁺ (M = Mo, W; X = 0, S, Se) clusters are examined. Interionic contacts significantly shorter than the sum of the van der Waals or ionic radii are fomd between the X atom of the X₂ ligands that occupy the axial position relative to the M₃ plane and the N, chalcogen, or halide of the counterion or identical ion. Centrosymmetric dimers involving the (₂-X₂) ligands are observed in the stmctures of several M₃X₄ ⁴⁺ derivatives. The X...X distance in these is also much less than the sum of the van der Waals radii. These SNI open occur in spite of the Coulombic repulsion of similarly charged species. The SNZ are classified using existing data. They play a definite role in forming of the crystal structure.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 150–167, March–April, 1993.     

Aqueous solution chemistry of [Mo3CuSe4]n+ (n = 4, 5) and [W3CuQ4]5+ (Q = S, Se) clusters

The triangular cluster [Mo3Se4(H2O)9]4+ reacts with Cu turnings to give a new heterometallic cuboidal cluster [Mo3CuSe4(H2O)10]4+(purple; UV/Vis lambda(epsilon): 352(3907), 509(2613)). The reaction of [Mo3Se4(H2O)9]4+ with CuCl afforded the 5+ cube [Mo3CuSe4(H2O)10]5+(red; UV/Vis lambda(epsilon): 356(5406), 500(3477)). In contrast, [W3Se4(H2O)9]4+ both with Cu and CuCl gives the 5+ cube, [W3CuSe4(H2O)10]5+(yellow-green; UV/Vis lambda(epsilon): 312(5327), 419(3256) and 628(680)). Cyclic voltammetry of [M3CuQ4(H2O)10]5+ in 2 M HCl (M = Mo, W; Q = S, Se) shows a reversible one-electron reduction wave for the Mo clusters, but no reduction occurs for the W clusters prior to H+ reduction. In HCl solutions, Cl is coordinated to the Cu site of the clusters, alongside some less extensive coordination to Mo and W, and for [W3(CuCl)S4(H2O)6Cl3]+, isolated as the supramolecular adduct with cucurbit[6]uril, [W3(CuCl)S4(H2O)6Cl3]2Cl2 x C36H36N24O12 x 12H2O, the crystal structure was determined (Cu-W 2.856(4) angstroms, W-W 2.7432(15) angstroms, Cu-Cl 2.167(13) angstroms).     

钼(钨)/铜/硫三核簇合物[A]2[MS4(CuCN)2] (M=Mo,W;A=Et4N,PPh4)的合成及晶体结构

合成了四个三核簇合物[A]2[MS4(CuCN)2](1A＝Et4N,M＝Mo;2A＝PPh4,M＝W;3A＝Et4N,M＝W;4A＝PPh4,M＝Mo),测定了[Et4N]2[MoS4(CuCN)2]*H2O(1*H2O)和[PPh4]2[WS4(CuCN)2]*0.5DMF*H2O(2*0.5DMF*H2O)的晶体结构.1和2的簇阴离子[MS4(CuCN)2]2-(M＝Mo,W)均具有一个双齿配体MS42-和两个CuCN形成的近似D2d对称性结构.     

Cyclic molecular materials based on [M2O2S2]2+ cores (M = Mo or W)

The purpose of this article is to illustrate how conventional precursors can serve, when used with a drop of imagination, to the synthesis of sophisticated inorganic rings and wheels. The self-condensation of the [M2O2S2]2+ fragments under acido-basic process produces, in the presence or absence of guest species, linear enchainment restricted to discrete cyclic entities. This approach was revealed to be a highly fruitful strategy for developing an extended family of compounds, differing in their nuclearity, size and shape, and the nature of the encapsulated guest molecule. Indeed, the resulting cycles delimit a cationic open cavity, which can be filled by neutral polar molecules such as aquo ligands or anionic molecules such as phosphates, polycarboxylates and even metalates. The flexibility of the rings is at the origin of interesting host-guest properties: the deformation (symmetry) and the adaptation (nuclearity) of the inorganic cycle are directly related to the size and the coordination requirements of the encapsulated substrate. The versatility of the metal coordination, octahedral or square pyramidal, confers dynamic properties to the ring. In the solid state, molecular rings assemble in striking 3-D networks based on direct cation-anion connections. Alkali cations are arranged in pillars or layers for anchoring the anionic rings.     

Nonvalent interactions in the crystal structures of (Et4N)2[Mo3S7Br6] and (Et4N)(H9O4)[Mo3S7Cl6] clusters

Crystal structures of (Et₄N)₂[Mo₃S₇Br₆] (I) and (Et₄N)(H₉O₄)[Mo₃S₇Cl₆] (II) clusters belonging to the class of Mo₃S ₇ ⁴⁺ were determined by X-ray diffraction analysis. Crystals I are orthorhombic a=19.106(3), b=12.930(2), c=29.887(5) Å, V=7383(2) ų, space group Pbca, Z=8, d_calc=2.253 g/cm³, R(F)=0.0402, wR(F²)=0.0587 for 2493 F_hkl>4σ. Crystals II are monoclinic, a=17.106(3), b=18.882(4), c=11.006(2), Å, β=126.13(3)°, V=2871.2(9) ų, space group Cc, Z=4, d_calc=2.147 g/cm³, R(F)=0.0181, wR(F²)=0.0445 for 2307 F_hkl>4σ. Structure I has an anion dimer with 3S_ax…Cl=3.258(4)–3.404(4) Å; the dimer is similar to that observed in the structures of A₂[M₃X₇Hal₆], A=Ph₄P⁺, Ph₃EtP⁺, and PPN⁺. In structure II, infinite chains of anions bonded by 3S_ax…Cl contacts of 3.183(3)–3.394(3) Å were found. A similar phenomenon was established earlier for the structure of (Et₄N)(H₉O₄)[Mo₃S₇Br₆] (III), which is not isostructural to II. Compounds II and III also differ in the structure of the H₉O₄ ⁺ cation: infinite helix in II and pyramid in III.     

Preparation and properties of dinitrogen trimethylphosphine complexes of molybdenum and tungsten—II: Synthesis and crystal structures of [MCl(N2)(PMe3)4] (M = Mo,W) and trans-[MoCl2(PMe3)4]

Sodium amalgam reduction of the complexes [MCl₃(PMe₃)₃] (M = Mo, W) in tetrahydrofuran, under dinitrogen, yields dark red-brown suspensions from which red-orange crystals of composition trans-[MCl(N₂)· (PMe₃)₄] can be collected. Spectroscopic and chemical evidence indicate the compounds are best formulated as mixtures of trans-[M(N₂)₂(PMe₃)₄] and trans-[MCl₂(PMe₃)₄] species, but attempts to isolate the pure bis(dinitro derivatives have proved unsuccessful. Single crystals of analytical composition [MCl(N₂)(PMe₃)₄] have been studied by X-ray crystallography, and the structure of trans-[MoCl₂(PMe₃)₄] has been determined for comparison. trans-[MCl(N₂)(PMe₃)₄] (M = Mo, W) and trans-[MoCl₂(PMe₃)₄] are all isostructural, crystallizing in the tetragonal space group I$\text{4}$2 trans-[MoCl(N₂)(PMe₃)₄] has a = 9.597(5), b = 12.294(6) Å, D_c = 1.36g cm^?3 Z = 2 and was refined to a final R value of 0.021 based on 319 independent observed reflections. The tungsten analogue has a = 9.573(4), b = 12.278(5) Å, D_c = 1.63g cm^?3 for Z = 2 and was refined to R = 0.19 with 322 independent observed reflections. trans-[MoCl₂(PMe₃)₄] has cell parameters a = 9.675(5), b = 12.311(6) Å D_c = 1.36 g cm^?3 for Z = 2 and was refined to R = 0.043 with 316 independent observed reflections. In each case the metal atom resides on a crystallographic $\text{4}$2m position. For trans-[MoCl(N₂)(PMe₃)₄] (M = Mo, W) the chlorine and dinitrogen ligands are disordered. M-N distances of 2.08(1) ? (M = Mo) and 2.04(2) ? (M = W) and M-Cl bond lengths of 2.415(8) Å (M = Mo) and 2.46(1) Å (M = W) are observed. In trans-[MoCl₂(PMe₃)₄], where there is no disorder, the Mo-Cl distance is 2.420(6) Å.     

Redistribution and fluxionality in heteropolyoxoperoxo complexes: [PO4[M2O2(mu-O2)2(O2)2]2]3- with M = Mo and/or W

When peroxotetramolybdophosphate, [(n-C4H9)4N]3[PO4[Mo2O2(mu-O2)2(O2)2]2], denoted (NBu4)3PMo4, and its tungsten(VI) analogue, (NBu4)3PW4, are mixed in acetonitrile at room temperature, redistribution occurs with the formation of three mixed-addenda species [PO4[Mo4-xWxO20]]3- (x = 1-3). The temperature dependence of the phosphorus-31 NMR spectra of a 1 1 mixture and of the pure salts, (NBu4)3PMo4 or (NBu4)3PW4, shows that [MO(O2)2] species are in chemical exchange, as are the [MOp] units of certain heteropolyacids (e.g. H3[PMo12O40] x aq and H3[PW12O40] x aq). However, there is no chemical exchange between free phosphate and [MO(O2)2] species in these systems; but there is fluxional behaviour involving PMo2W2, PMo4 and PW4. This is attributed to the rapid equilibrium between isomers (PMo2W2) and to equilibrium between anionic structures with tridentate (mu-eta2:eta1-O22-) and bidentate (eta2-O22-) modes of coordination for the two peroxo groups of the [M2O2(mu-O2)2(O2)2] moieties.     

Cluster oxalate complexes [M3(mu3-Q)(mu2-Q2)3(C2O4)3]2- and [Mo3(mu3-Q)(mu2-Q)3(C2O4)3(H2O)3]2- (M = Mo, W; Q = S, Se): mechanochemical synthesis and crystal structure

Mechanochemical reaction of cluster coordination polymers 1infinity[M3Q7Br4] (M = Mo, W; Q = S, Se) with solid K2C2O4 leads to cluster core excision with the formation of anionic complexes [M3Q7(C2O4)3]2-. Extraction of the reaction mixture with water followed by crystallization gives crystalline K2[M3Q7(C2O4)3].0.5KBr.nH2O (M = Mo, Q = S, n = 3 (1); M = Mo, Q = Se, n = 4 (2); M = W, Q = S, n = 5 (3)). Cs2[Mo3S7(C2O4)3].0.5CsCl.3.5H2O (4) and (Et4N)1.5H0.5K{[Mo3S7(C2O4)3]Br}.2H2O (5) were also prepared. Close Q...Br contacts result in the formation of ionic triples {[M3Q7(C2O4)3](2)Br}5- in 1-4 and the 1:1 adduct {[Mo3S7(C2O4)3]Br}3- in 5. Treatment of 1 or 2 with PPh(3) leads to chalcogen abstraction with the formation of [Mo3(mu3-Q)(mu2-Q)3(C2O4)3(H2O)3]2-, isolated as (Ph4P)2[Mo3(mu3-S)(mu2-S)3(C2O4)3(H2O)3].11H2O (6) and (Ph4P2[Mo3(mu3-Se)(mu2-Se)3(C2O4)3(H2O)3].8.5H2O.0.5C2H5OH (7). All compounds were characterized by X-ray structure analysis. IR, Raman, electronic, and 77Se NMR spectra are also reported. Thermal decomposition of 1-3 was studied by thermogravimetry.     

两个具有[Mo~3M'S~4]^5^+(M'=Mo,W)簇芯的原子簇化合物的合 成和晶体结构

以Mo~3S~4(dtp)~4.H~2O和M'(CO)~6(M'=Mo,W)为起始物在羧酸介质下通过[3+1]模式合成,分别得到一个同核和一个异核四核簇[Mo~4S~4(μ-C~2H~5CO~2)~2(dtpH)(dtp)~3]4和[Mo~3WS~4(μ-CH~3CO~2)~2(dtpH)(dtp)~3]5[dtp=(EtO)~2PS~2^-;dtpH=(EtO)~2P(S)(SH)]。两个簇合物以单晶X射线分析和IR谱学进行结构表征,它们均具有[M~4S~4]^5^+类立方烷簇芯。     

Synthesis, crystal structure and thermal properties of [Co(NH3)5Cl]MO4 (M = Mo, W)

Crystal structures of [Co(NH₃)₅Cl]MoO₄ and [Co(NH₃)₅Cl]WO₄ complex salts are determined by single crystal X-ray diffraction. It is demonstrated for both salts that within the temperature range T = ?123?20°C there is a negative thermal expansion (about 0.26%) towards the c axis of the orthorhombic unit cell (Pnma space group). Thermal properties of the salts are investigated. The phase composition of the products obtained on heating the salts in different gas atmospheres is studied.     

Preparation and properties of the full series of cuboidal clusters [Mo(x)W4-xSe4(H2O)12]n+ (n = 4-6) and their derivatives

Hydrothermal reactions between incomplete cuboidal cluster aqua complexes [M3Q4(H2O)9]4+ and M(CO)6 (M = Mo, W; Q = S, Se) offer easy access to the corresponding cuboidal clusters M4Q4. The complete series of homometal and mixed Mo/W clusters [Mo(x)W4-xQ4(H2O)12]n+ (x = 0-4, n = 4-6) has been prepared. Upon oxidation of the mixed-metal clusters, it is the W atom which is lost, allowing selective preparation of new trinuclear clusters [Mo2WSe4(H2O)9]4+ and [MoW2Se4(H2O)9]4+. The aqua complexes were converted by ligand exchange reactions into dithiophosphato and thiocyanato complexes, and crystal structures of [W4S4((EtO)2PS2)6], [MoW3S4((EtO)2PS2)6], [Mo4Se4((EtO)2PS2)6], [W4Se4((i-PrO)2PS2)6], and (NH4)6[W4Se4(NCS)12]-4H20 were determined. Cyclic voltammetry was performed on [Mo(x)W4-xCO4(H2O)12]n+, showing reversible redox waves 6+/5+ and 5+/4+. The lower oxidation states are more difficult to access as the number of W atoms increases. The [Mo2WSe4(H2O)9]4+ and [MoW2Se4(H2O)9]4+ species were derivatized into [Mo2WSe4(acac)3(py)3]+ and [MoW2Se4(acac)3(py)3]+, which were also studied by CV. When appropriate, the products were also characterized by FAB-MS and NMR (31P, 1H) data.     

Two novel molybdenum complexes containing [Mo2O2S2]2+ fragment: synthesis,crystal structures and catalytic studies

Mo₂O₂S₂(HGly)(Gly)₂ 1 and K₆[Mo₂O₂S₂(nta)₂][Mo₂O₂S₂(ntaH)₂]^·4H₂O 2 were synthesized by the reactions of (NH₄)₂MoS₄ and amino acids L (L = glycine, nitrilotriacetic acid) in ethanol–water medium at ambient temperature. The two complexes were characterized by elemental analysis, infrared spectra, UV–visible spectra, TG–DTA and XPS. X‐ray crystallographic structural analyses revealed that compound 1 is a binuclear Mo? S? glycinate complex, a glycinate ligand is coordinated to each molybdenum atom through its amine nitrogen and carboxylato oxygen, respectively, and the third glycinate acts as a bridge through its two carboxylato oxygens linking the two molybdenum atoms. Compound 2 is also a binuclear Mo? S complex with two nitrilotriacetate ligands, each of which is coordinated to a molybdenum atom via its two β‐carboxylato oxygens and a nitrogen atom. Simultaneously, each molybdenum atom in 1 and 2 is chelated to a terminal oxygen and two bridging sulfurs to complete the octahedral configuration. Their catalytic activities in the reduction from C₂H₂ to C₂H₄ as well as other binuclear Mo? S? polycarboxylate complexes, a [Fe₄S₄] single cubane and a chainlike Mo? Fe? S compound were investigated and it was found that 1 exhibited relatively good catalytic activity. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and structure of nickel-containing cuboidal clusters derived from [W3Se4(H2O)9]4+. Site-differentiated substitution at the nickel site in the series [W3NiQ4(H2O)10]4+ (Q = S, Se)

New Ni-containing heterometallic cuboidal cluster aqua complex [W3(NiCl)Se4(H2O)9]3+, the missing link in the family of the M3NiQ4 clusters (M = Mo, W; Q = S, Se), has been prepared by the reaction of [W3Se4(H2O)9]4+ with Ni in 2 M HCl. Single crystals of edge-linked double-cuboidal cluster [{W3NiSe4(H2O)9}2](pts)8.18H2O (pts = p-toluenesulfonate) were grown from the solution of the aqua complex in 3 M Hpts, and their structures were determined. The Ni site in the clusters [W3(NiCl)Q4(H2O)9]3+ selectively coordinates typical pi-acceptor ligands such as CO, olefins, acetylenes, phosphines, arsines, or SnCl3-. This allows stabilization by coordination of such elusive species as HP(OH)2 and As(OH)3. The stability constants for coordination of HP(OH)2, As(OH)3, and SnCl3- were determined. The Se for S substitution increases the stability by 1-2 orders of magnitude. Supramolecular adducts with cucurbit[6]uril (Cuc), [W3(Ni(HP(OH)2))Q4(H2O)9]Cl4.Cuc.11H2O and [W3(NiAs(OH)3)S4(H2O)8Cl]Cl3.Cuc.13H2O, were isolated and structurally characterized.     

[MoFe3S4]3+ and [MoFe3S4]2+ cubane clusters containing a pentamethylcyclopentadienyl molybdenum moiety

A series of organometallic molybdenum/iron/sulfur clusters of the general formula [Cp¹MoFe₃S₄L_n]^m (Cp¹ = η⁵-C₅Me₅; L = S^tBu, SPh, Cl, I, n = 3, m = 1−; L_n = I₂(P^tBu₃), m = 0; L = 2,6-diisopropylphenylisocyanide (ArNC), n = 7, m = 1+) have been synthesized. A cubane cluster (PPh₄)[Cp¹MoFe₃S₄(S^tBu)₃] (2) was isolated from a self-assembly reaction of Cp¹Mo(S^tBu)₃ (1), FeCl₃, LiS^tBu, and S₈ followed by cation exchange with PPh₄Br in CH₃CN, while an analogous cluster (PPh₄)[Cp¹MoFe₃S₄(SPh)₃] (3) was obtained from the Cp¹MoCl₄/FeCl₃/LiSPh/PPh₄Br reaction system or from a ligand substitution reaction of 2 with PhSH. Treatment of 2 with benzoyl chloride gave rise to (PPh₄)[Cp¹MoFe₃S₄Cl₃] (4), which was in turn converted to (PPh₄)[Cp¹MoFe₃S₄I₃] (5) by the reaction with NaI. A neutral cubane cluster Cp¹MoFe₃S₄I₂(P^tBu₃) (6) was generated upon treating 5 with P^tBu₃. Although reduction of 4 by cobaltocene under the presence of ArNC resulted in a disproportionation of the cubane core to give Fe₄S₄(ArNC)₉Cl (7), a similar reduction reaction of 5 produced [Cp¹MoFe₃S₄(ArNC)₇]I (8), where the MoFe₃S₄ core was retained. The crystal structures of 4–6, and 8 were determined by the X-ray analysis.     

Guest-Dependent Pressure-Induced Spin Crossover in FeII4[MIV(CN)8]2 (M=Mo,W) Cluster-Based Material Showing Persistent Solvent-Driven Structural Transformations

Discrete molecular species that can perform certain functions in response to multiple external stimuli constitute a special class of multifunctional molecular materials called smart molecules. Herein, cyanido-bridged coordination clusters {[Fe^II(2-pyrpy)₂]₄[M^IV(CN)₈]₂} ⋅ 4 MeOH ⋅ 6 H₂O (M=Mo ( 1 solv ), M=W ( 2 solv ) and 2-pyrpy=2-(1-pyrazolyl)pyridine are presented, which show persistent solvent driven single-crystal-to-single-crystal transformations upon sorption/desorption of water and methanol molecules. Three full desolvation–resolvation cycles with the concomitant change of the host molecules do not damage the single crystals. More importantly, the Fe₄M₂ molecules constitute a unique example where the presence of the guests directly affects the pressure-induced thermal spin crossover (SCO) phenomenon occurring at the Fe^II centres. The hydrated phases show a partial SCO with approximately two out-of-four Fe^II centres undergoing a gradual thermal SCO at 1 GPa, while in the anhydrous form the pressure-induced SCO effect is almost quenched with only 15 % of the Fe^II centres undergoing high-spin to low-spin transition at 1 GPa.