Mechanistic insight into the reactivity of oxotransferases by novel asymmetric dioxomolybdenum(VI) model complexes

The asymmetric molybdenum(VI) dioxo complexes of the bis(phenolate) ligands 1,4‐bis(2‐hydroxybenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐4‐methylbenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐3,5‐dimethylbenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐3,5‐di‐tert‐butylbenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐4‐flurobenzyl)‐1,4‐diazepane, and 1,4‐bis(2‐hydroxy‐4‐chlorobenzyl)‐1,4‐diazepane (H₂(L1)–H₂(L6), respectively) have been isolated and studied as functional models for molybdenum oxotransferase enzymes. These complexes have been characterized as asymmetric complexes of type [MoO₂(L)] 1–6 by using NMR spectroscopy, mass spectrometry, elemental analysis, and electrochemical methods. The molecular structures of [MoO₂(L)] 1–4 have been successfully determined by single‐crystal X‐ray diffraction analyses, which show them to exhibit a distorted octahedral coordination geometry around molybdenum(VI) in an asymmetrical cis‐β configuration. The Mo? O_oxo bond lengths differ only by ≈0.01 Å. Complexes 1 , 2 , 5 , and 6 exhibit two successive Mo^VI/Mo^V (E_1/2, ?1.141 to ?1.848 V) and Mo^V/Mo^IV (E_1/2, ?1.531 to ?2.114 V) redox processes. However, only the Mo^VI/Mo^V redox couple was observed for 3 and 4 , suggesting that the subsequent reduction of the molybdenum(V) species is difficult. Complexes 1 , 2 , 5 , and 6 elicit efficient catalytic oxygen‐atom transfer (OAT) from dimethylsulfoxide (DMSO) to PMe₃ at 65 °C at a significantly faster rate than the symmetric molybdenum(VI) complexes of the analogous linear bis(phenolate) ligands known so far to exhibit OAT reactions at a higher temperature (130 °C). However, complexes 3 and 4 fail to perform the OAT reaction from DMSO to PMe₃ at 65 °C. DFT/B3LYP calculations on the OAT mechanism reveal a strong trans effect.     

Economical Oxygenation of Olefins and Sulfides Catalyzed by New Molybdenum(VI) Tridentate Schiff Base Complexes: Synthesis and Crystal Structure

Abstract. New cis‐dioxomolybdenum(VI) complexes (MoO₂Y^xCH₃OH) were synthesized using MoO₂(acac)₂ and 2[(1‐hydroxy‐2‐methylpropane‐2‐ylimino)methyl]phenol derivatives as tridentate ONO donor Schiff base ligands (H₂Y^x). MoY¹ was crystallized in orthorhombic space group Pbca. The epoxidation of olefins using tert‐butyl hydroperoxide and oxidation of sulfides to the sulfoxides by hydrogen peroxide were efficiently enhanced by the catalytic activity of title Mo^VI complexes with excellent selectivity. The high efficiency and relative stability of the catalysts was observed by turnover number and UV/Vis investigations. The electron‐rich and bulky ligands promoted the effectiveness of the catalysts.     

Molybdenum(VI), (V) and (IV) complexes with chiral benzoin thiosemicarbazone

The chiral (ONS) dianionic Schiff base ligand benzoin thiosemicarbazone (H₂L) reacts with MoO₂(acac)₂ to give the polymeric complex [(MoO₂L) _n ] (1) (Type 1). The reaction of MoO₂L with pyridine (py), 3-picoline (3-pic) or 4-picoline (4-pic) gives [Mo^VIO₂LD] (D = py, 3-pic or 4-pic) (Type 1). Further, the reaction of [MoO₂L] or [MoO₂LD] with PPh₃ or reaction of [MoO₂L] with PPh₃ (plus bpy or phen, D) in the presence of donor reagents D gives [Mo^IVOL] or [Mo^IVOLD] (Type 2). On the other hand, the reaction of [MoO₂L] with hydrazides (zdhH₃) such as benzoylhydrazine (bhH₃), isonicotinoylhydrazine (inhH₃), nicotinoylhydrazine (nhH₃), salicyloylhydrazine (slhH₃) and thiosemicarbazide (tscH₃) produced non-oxo–diazenido complexes [MoL(zdh)] (Type 3). The complexes have been characterized by elemental analyses, molar conductance, magnetic moment, electronic, i.r. and e.s.r. spectroscopic measurements.     

A Ditopic Catechol Phosphane as Building Block for Selective Construction of Heterometallic Complexes with Early and Late Transition Metal Centers

Base‐assisted reaction of catechol phosphane 2 (H₂L) with [M′Cl₂(cod)] (cod = 1, 5‐cyclooctadiene, M′ = Pd, Pt) yielded chelate complexes [M′(HL)₂] ( 7a, b ). Spectroscopic and single‐crystal X‐ray diffraction studies revealed that both complexes feature cis‐configuration of the P‐ and O‐donor atoms in solution and in the solid state. Reaction of 7a, b with acetylacetonato or alkoxide complexes [MO₂(acac)₂] (M = Mo, W), [VO(acac)₂], [{Ti(μ‐O)(acac)₂}₂], or Ti(OiPr)₄ gave good to excellent yields of early‐late heterometallic complexes [MO_n(μ‐L)₂M′] (MO_n = MoO₂, WO₂, VO; 8a, b – 10a, b ) or [Ti(RO‐1κO)₂(μ‐L ‐1κ²O, O'‐2κ²P, O)₂Pd] (R = Me, iPr; 11a, b ), which were inaccessible via other synthetic routes. Spectroscopic and single‐crystal X‐ray diffraction studies revealed that the early metal centres in 8a, b, 9b and in 11b feature distorted octahedral coordination spheres with rigid transoid alignment of the catechol ring planes. Vanadium complexes 10a, b exhibit a square‐pyramidal coordination sphere with cisoid alignment of the catechol ring planes and evidence for intermolecular pairing via weak VO ··· Pd contacts in the solid state; complexes 8 , 9 do not undergo conformational inversion on the NMR time‐scale. The molecular structure of Ti complex 11a is characterized by a different orientation of the catechol moieties, which can be envisaged to picture an intermediate state during a configuration inversion process, and a strong hydrogen bridge between a terminally coordinated catecholato‐oxygen atom and a solvent molecule (MeOH). Solution NMR studies indicate that the (MeO)₂Ti(μ‐L)₂M' framework is in this case conformationally labile and that the MeO ligands undergo intermolecular dynamic exchange with the solvent.     

One—dimensional Anion—chain Containing [Mo2O6（pic）2]^2—Unit Connected by Unclassical Hydrogen Bond

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Redox Non‐Innocence and Isomer‐Specific Oxidative Functionalization of Ruthenium‐Coordinated β‐Ketoiminate

This article deals with isomeric ruthenium complexes [Ru^III(L^R)₂(acac)] (S=1/2) involving unsymmetric β‐ketoiminates (AcNac) (L^R=R‐AcNac, R=H ( 1 ), Cl ( 2 ), OMe ( 3 ); acac=acetylacetonate) [R=para‐substituents (H, Cl, OMe) of N‐bearing aryl group]. The isomeric identities of the complexes, cct (cis‐cis‐trans, blue, a ), ctc (cis‐trans‐cis, green, b ) and ccc (cis‐cis‐cis_, pink, c ) with respect to oxygen (acac), oxygen (L) and nitrogen (L) donors, respectively, were authenticated by their single‐crystal X‐ray structures and spectroscopic/electrochemical features. One‐electron reversible oxidation and reduction processes of 1 – 3 led to the electronic formulations of [Ru^III(L)(L ^? )(acac)]⁺ and [Ru^II(L)₂(acac)]^? for 1 ⁺‐ 3 ⁺ (S=1) and 1^? – 3^? (S=0), respectively. The triplet state of 1 ⁺‐ 3 ⁺ was corroborated by its forbidden weak half‐field signal near g≈4.0 at 4 K, revealing the non‐innocent feature of L. Interestingly, among the three isomeric forms ( a – c in 1 – 3 ), the ctc ( b in 2 b or 3 b ) isomer selectively underwent oxidative functionalization at the central β‐carbon (C?H→C=O) of one of the L ligands in air, leading to the formation of diamagnetic [Ru^II(L)(L ′ )(acac)] (L ′ =diketoimine) in 4 / 4′ . Mechanistic aspects of the oxygenation process of AcNac in 2 b were also explored via kinetic and theoretical studies.     

Synthesis,Structure and Characterization of Dinuclear Pentacoordinate Molybdenum(V) Complexes with Thiosemicarbazone Ligands

New dinuclear pentacoordinate molybdenum(V) complexes, [Mo₂^VO₃L₂] [L = thiosemicarbazonato ligand: C₆H₄(O)CH:NN:C(S)NHR′ and C₁₀H₆(O)CH:NN:C(S)NHR′; R′ = H, CH₃, C₆H₅) were obtained either by oxygen atom abstraction from Mo^VIO₂L with triphenylphosphine or by using [Mo₂O₃(acac)₄] in the reaction with the corresponding ligands H₂L. Crystal and molecular structure of [Mo₂O₃{C₆H₄(O)CH:NN:C(S)NHC₆H₅}₂] · CH₃CN has been determined by the single‐crystal X‐ray diffraction method.     

Synthesis,Characterization, and Crystal Structure of Mononuclear and Dinuclear Dioxomolybdenum(VI) Complexes with Tridentate Schiff‐base Ligands. Part 2

Mononuclear [MoO₂LD], and dinuclear [MoO₂L]₂ or [MoO₂L]₂ · D dixomolybdenum(VI) complexes have been prepared by the reaction of tridentate Schiff‐base ligands L with [MoO₂(acac)₂]. The Schiff‐base ligands have been synthesized from salicylaldehyde ( 1 , 1a , 1c , 1d ), 2‐hydroxy‐1‐naphthaldehyde ( 2 , 2c ) and 2‐hydroxy‐3‐methoxybenzaldehyde ( 3a , 3b , 3c , 3d , 3e ) with 2‐amino‐p‐cresol. All prepared complexes consist of cis‐MoO₂²⁺core coordinated by Schiff‐base ligand through two deprotonated hydroxyl groups and one imino nitrogen atom. The usual octahedral coordination around the molybdenum atoms is completed by the neutral ligand D (methanol, ethanol, dimethyl sulfoxide, imidazole or 4, 4′‐bipyridine). All compounds were characterized by elemental analyses, IR spectroscopy and some of them by X‐ray crystallography ( 1a , 2c , 3a , 3b , 3c and 3e ).     

Chemistry of oxomolybdenum(V) and (VI) complexes incorporating oxygen,nitrogen and/or sulfur donor atoms. Part 1. Synthesis and characterization of [Mo2O3L4] (LH = HSCH2CH2CO2H,HSCH2CO2Me or HSCH2CH2CO2Me) and [MoO2L′2] (L′H = HOC6H4NH2, HOCH2C6H4NH2, HOC6H4CHO or HOC10H8N)

Reactions of an acidified aqueous solution of Na₂MoO₄ · 2H₂O with 3-mercaptopropionic acid, 2-mercaptomethylethanoate and 3-mercaptomethyl propanate yield blue oxo-bridged Mo^V complexes of the type [Mo₂O₃L₄], whereas corresponding reactions with 2-aminophenol, 2-aminobenzyl alcohol, salicylaldehyde and 2-methyl-8-hydroxyquinoline, yield yellow dioxomolybdenum(VI) complexes, [MoO₂L′₂]. All these coloured solids are sparingly soluble, even in coordinating solvents. They have been characterized by elemental and spectroscopic analysis.     

Chains of (4,4′‐bipyridyl)copper(I) bridged by dimolybdate units

The crystal structure of the title compound, poly­[bis‐[copper(I)‐μ‐(4,4′‐bipyridyl)‐N:N′]‐μ‐dimolybdato‐O:O′],[Cu₂(C₁₀H₈N₂)₂{Mo₂O₇}]_n, consists of {Mo₂O₇}^2? units (with the central O atom lying on twofold symmetry axes) and [Cu(4,4′‐bipy)]_nⁿ⁺ chains (bipy = bipyridyl); the chains are generated by a c‐glide‐plane operation. The {Mo₂O₇}^2? units are covalently bridged to two [Cu(4,4′‐bipy)]_nⁿ⁺ chains, forming a complex with a bridged double‐chain structure. The Cu—O and Cu—N distances are 2.191 (3) and 1.933 (3) Å, respectively.     

Hydrothermal Synthesis and Structural Characterization of a Novel Organic—Inorganic Hybrid Compound {[Cu（2,2′—bpy）2]2—Mo8O26}

A novel organic-inorganic hybrid compound {[Cu(2,2′-bpy)2]2Mo8O26} has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group, Pna21,with a=2.4164(5),b=1.8281(4),c=1.1877(2)nm,V=5.247(2)nm^3,Z=4,and final R1=0.0331,wR2=0.0727.The structure consists of discrete {[Cu(2,2′-bpy)2]2Mo8O26} clusters,constructed from a β-octamolybdate subunit[Mo8O26]^4- covalently bonded to two [Cu(2,2′-bpy)2]^2 coordination complex cations via bridging oxo groups.In addition,the spectroscopic properties and thernal behavior of this compound have been investigated by spectroscopic techniques (UV-vis,IR,Raman and EPR spectra) and TG analysis.     

First Mixed Alkaline Uranyl Molybdates: Synthesis and Crystal Structures of CsNa3[(UO2)4O4(Mo2O8)] and Cs2Na8[(UO2)8O8(Mo5O20)]

Two new mixed alkaline uranyl molybdates CsNa₃[(UO₂)₄O₄Mo₂O₈] ( 1 ) and Cs₂Na₈[(UO₂)₈O₈(Mo₅O₂₀)] ( 2 ) have been obtained by high‐temperature solid state reactions. Their crystal structures have been solved by direct methods: Compound 1 : triclinic, P , a = 6.46(1), b = 6.90(1), c = 11.381(2) Å, α = 84.3(1), β = 91.91(1), γ = 80.23(1)°, V = 488.6(2) ų, R₁ = 0.06 for 2865 unique reflections with |F_o| ≥ 4σ_F; Compound 2 : orthorhombic, Ibam, a = 6.8460(2), b = 23.3855(7), c = 12.3373(3) Å, V = 1975.2(1) ų, R₁ = 0.049 for 2120 unique reflections with |F_o| ≥ 4σ_F. The structure of 1 contains complex sheets of UrO₅ pentagonal bipyramids and molybdenum polyhedra. The sheets have [(UO₂)₂O₂(MoO₅)] composition. Natrium and cesium atoms are located in the interlayer space. Cesium atoms are situated between the molybdenum clusters, whereas natrium atoms are segregated between the uranyl complexes. The large Cs⁺ ions are localized between the Mo₂O₉ groups and force the molybdenum polyhedra to rotate relative to the [(UO₂)₂O₂(MoO₅)] sheets. Such rotation is impossible for U⁶⁺ polyhedra due to their rigid edge‐sharing complexes. The distance between the U⁶⁺ polyhedra vertices of neighboring layers is 3.8 Å, that allows the Na⁺ ion to be positioned between the uranyl groups. The crystal structure of 2 is based upon a framework consisting of [(UO₂)₂O₂(MoO₅)] sheets parallel to (010). The sheets are linked into a 3‐D framework by sharing vertices with the Mo(2)O₄ tetrahedra, located between the sheets. Each MoO₄ tetrahedron shares two of its corners with two MoO₆ octahedra in the sheet above, and the other two with MoO₆ octahedra of the sheet below. Thus four MoO₆ octahedra and one MoO₄ tetrahedron form chains of composition Mo₅O₁₈. The resulting framework has a system of channels occupied by the Cs⁺ and Na⁺ ions.     

Dioxomolybdenum(VI) and dioxotungsten(VI) complexes: efficient catalytic activity for crosslinking reaction in ethylene‐vinyl acetate copolymer/alkoxysilane composites

The catalytic performances of several bis(acetylacetonato)metal complexes [Cu(acac)₂, Zn(acac)₂, TiO(acac)₂, VO(acac)₂, MoO₂(acac)₂, and WO₂(acac)₂] were investigated for the crosslinking reaction via transesterifications in the ethylene‐vinyl acetate copolymer/tetraethoxysilane (EVA/TEOS) composite system by means of dynamic attenuated total reflectance Fourier transform infrared, solvent swelling, and solid‐state ²⁹Si cross polarization/magic angle spinning nuclear magnetic resonance techniques. Results of the kinetic examination revealed that MoO₂(acac)₂ and WO₂(acac)₂ exhibited a higher catalytic activity than di‐n‐butyltin(IV) oxide, which is a catalyst most commonly used for the transesterification process in polymer system, but has a toxic effect on the environmental health. And furthermore, the crosslink density and final siloxane network structure of crosslinked EVA/TEOS composites are found to be greatly correlated with the catalyst used. On the basis of the S_N2‐Si pathway, a plausible catalytic mechanism of MoO₂(acac)₂ and WO₂(acac)₂ was proposed for the crosslinking reaction via transesterifications of the vinyl acetate moieties in EVA backbone with the ethoxysilane groups in one TEOS molecule. The findings in this study may fill the blank in the high performance and environmentally friendly catalyst in the field of the crosslinking reactions in polymer system and provide useful clue for other transesterifications. Copyright © 2015 John Wiley & Sons, Ltd.     

Hydrothermal Synthesis and Structures of Two New Molybdenum Phosphate Compounds based on Keggin Cluster Units

Two new molybdenum phosphate complexes, [Cu₂(phen)₄(μ‐Cl)][PMo₁₂O₄₀]·H₂O (phen = 1,10‐phenanthroline) ( 1 ) and (Hbpy)[Cu^I(bpy)]₂[PMo^V₂Mo^VI₁₀O₃₉] (bpy = 4,4′‐bipyridine) ( 2 ), have been prepared under mild hydrothermal conditions and structurally characterized by single‐crystal X‐ray diffraction. Compounds 1 and 2 crystallize in triclinic system, space group , with a = 12.5458(7) Å, b = 13.4486(8) Å, c = 21.2406(12) Å, α = 99.7020(10)°, β = 94.2320(10)°, γ = 95.0890(10)°, V = 3504.2(3) ų and Z = 2 for 1 , and a = 10.7871(6) Å, b = 10.9016(6) Å, c = 12.7897(7) Å, α = 96.8500(10)°, β = 110.0850(10)°, γ = 103.5800(10)°, V = 1339.74(13) ų and Z = 1 for 2 . Compound 1 contains a [Cu₂(phen)₄(μ‐Cl)]³⁺ cation in which two similar [Cu(phen)₂] units are bridged by one chlorine atom. Compound 2 contains one‐dimensional straight chain of Keggin polyoxoanions [PMo^V₂Mo^VI₁₀O₃₉]_n^3? and two linear cationic chains of [Cu^I(bpy)]_nⁿ⁺. The molecular packing shows a two‐dimensional network, which is formed by the cross of the linear Keggin anions and Cu‐bpy cations.     

Diamond‐ and Graphite‐Like Octacyanometalate‐Based Polymers Induced by Metal Ions

By using cyclohexane‐1,2‐diamine (chxn), Ni(ClO₄)₂ ? 6H₂O and Na₃[Mo(CN)₈] ? 4H₂O, a 3D diamond‐like polymer {[Ni^II(chxn)₂]₂[Mo^IV(CN)₈] ? 8H₂O}_n ( 1 ) was synthesised, whereas the reaction of chxn and Cu(ClO₄)₂ ? 6H₂O with Na₃[M^V(CN)₈] ? 4H₂O (M=Mo, W) afforded two isomorphous graphite‐like complexes {[Cu^II(chxn)₂]₃[Mo^V(CN)₈]₂ ? 2H₂O}_n ( 2 ) and {[Cu^II(chxn)₂]₃[W^V(CN)₈]₂ ? 2H₂O}_n ( 3 ). When the same synthetic procedure was employed, but replacing Na₃[Mo(CN)₈] ? 4H₂O by (Bu₃NH)₃[Mo(CN)₈] ? 4H₂O (Bu₃N=tributylamine), {[Cu^II(chxn)₂Mo^IV(CN)₈][Cu^II(chxn)₂] ? 2H₂O}_n ( 4 ) was obtained. Single‐crystal X‐ray diffraction analyses showed that the framework of 4 is similar to 2 and 3 , except that a discrete [Cu(chxn)₂]²⁺ moiety in 4 possesses large channels of parallel adjacent layers. The experimental results showed that in this system, the diamond‐ or graphite‐like framework was strongly influenced by the inducement of metal ions. The magnetic properties illustrate that the diamagnetic [Mo^IV(CN)₈] bridges mediate very weak antiferromagnetic coupling between the Ni^II ions in 1 , but lead to the paramagnetic behaviour in 4 because [Mo^IV(CN)₈] weakly coordinates to the Cu^II ions. The magnetic investigations of 2 and 3 indicate the presence of ferromagnetic coupling between the Cu^II and W^V/Mo^V ions, and the more diffuse 5d orbitals lead to a stronger magnetic coupling interaction between the W^V and Cu^II ions than between the Mo^V and Cu^II ions.     

Two mononuclear molybdenum(VI) oxo complexes with tridentate hydrazone ligands: Synthesis,structures, and thermal stability

A reaction of [MoO₂(acac)₂] (where acac = acetylacetonate) with two hydrazone ligands in methanol yields two mononuclear molybdenum(VI) oxo complexes with the general formula [MoO₂L(CH₃OH)], where L = L¹=(4-nitrophenoxy)acetic acid [1-(5-chloro-2-hydroxyphenyl)methylidene]hydrazide (H₂L¹) and L = L²=4-dimethylaminobenzoic acid [1-(2-hydroxy-3-methoxyphenyl)methylidene]hydrazide (H₂L²). The crystal and molecular structures of the complexes are determined by the single crystal X-ray diffraction method. All of the investigated compounds are further characterized by the elemental analysis, FT-IR spectra, and thermogravimetric analysies. Single crystal X-ray structural studies indicate that hydrazone ligands coordinate to MoO₂ cores through enolate oxygen, phenolate oxygen, and azomethine nitrogen atoms. The Mo atoms in both complexes are in octahedral coordination.     

Room‐Temperature and Aqueous‐Phase Synthesis of Plasmonic Molybdenum Oxide Nanoparticles for Visible‐Light‐Enhanced Hydrogen Generation

A straightforward aqueous synthesis of MoO_3?x nanoparticles at room temperature was developed by using (NH₄)₆Mo₇O₂₄?4 H₂O and MoCl₅ as precursors in the absence of reductants, inert gas, and organic solvents. SEM and TEM images indicate the as‐prepared products are nanoparticles with diameters of 90–180 nm. The diffuse reflectance UV‐visible‐near‐IR spectra of the samples indicate localized surface plasmon resonance (LSPR) properties generated by the introduction of oxygen vacancies. Owing to its strong plasmonic absorption in the visible‐light and near‐infrared region, such nanostructures exhibit an enhancement of activity toward visible‐light catalytic hydrogen generation. MoO_3?x nanoparticles synthesized with a molar ratio of Mo^VI/Mo^V 1:1 show the highest yield of H₂ evolution. The cycling catalytic performance has been investigated to indicate the structural and chemical stability of the as‐prepared plasmonic MoO_3?x nanoparticles, which reveals its potential application in visible‐light catalytic hydrogen production.     

Synthesis of Molybdovanadates Coordinated by Oxalato Ligands. The Crystal Structure of K6[Mo6V2O24(C2O4)2]·6H2O

The oxalato complex of a polyoxomolybdovanadate, K₆[Mo₆V₂O₂₄(C₂O₄)₂]·6H₂O has been obtained by reaction of potassium molybdate, ammonium vanadate and tartaric or ascorbic acid. Such conversion of dicarboxylate into oxalate ions indicates the catalytic role of molybdenum. Complexes of analogous composition also were obtained in the reactions of MoO₃, V₂O₅ and potassium oxalate, or M ₂CO₃ (M = Rb, Cs) and oxalic acid. The centrosymmetrical molybdovanadate anion [Mo₆V₂O₂₄(C₂O₄)₂]^6- consists of six MoO₆ and two VO₆ edge-sharing octahedra to give the n -[Mo₆O₂₆]^4- structure. All complexes were characterized by powder and single crystal X-ray analyses, ESR and IR spectra and TG and DSC measurements.     

Bis­[benzidinium(1–)] pentamolybdate

The title compound, {(C₁₂H₁₃N₂)₂[Mo₅O₁₆]}_n, was synthesized under hydro­thermal conditions. The structure contains a two‐dimensional layer, constructed from [(Mo₄O₁₄)_n]⁴ⁿ⁻ chains linked through MoO₆ octahedra, which lie across twofold axes. The [(Mo₄O₁₄)_n]⁴ⁿ⁻ chain consists of [Mo₄O₁₄]⁴⁻ clusters connected to one another by sharing their MoO₅ square‐pyramidal and MoO₆ octahedral vertices in an anti disposition. The layers are linked by the cation, to which they are connected via N—H⋯O hydrogen bonds.     

Inorganic−Organic Hybrid Polymers via Hydrothermal Syntheses: Tetraaquahexakis(pyrazine‐2‐carboxylato)pentacopper(4+) Hexacosaoxooctamolybdate(4−) Polymer ({[Cu5(pzca)6(H2O)4][Mo8O26]}n; pzca=Pyrazine‐2‐carboxylate) and Dicopperdecaoxo(pyrazine)trimolybdenum Polymer ([Mo3Cu2O10(pz)]n; pz=pyrazine)

Hydrothermal reactions of MoO₃, CuO, and pyrazine‐2‐carboxylic acid (Hpzca) resulted in two polymeric complexes, {[Cu₅(pzca)₆(H₂O)₄][Mo₈O₂₆]}_n ( 1 ; pzca=pyrazine‐2‐carboxylate) and [Mo₃Cu₂O₁₀(pz)]_n ( 2 ; pz=pyrazine). The former crystallized in the monoclinic space group P2₁/c with a=10.805(3) Å, b=13.061(5) Å, c=13.337(10) Å, β=90.20(4)°, V=2729(2) ų, and Z=2. The later crystallized in the orthorhombic space group Pnma with a=12.385(2) Å, b=7.6044(9) Å, c=12.7880(14) Å, V=1204.4(2) ų, and Z=4. X‐Ray diffraction analysis revealed that 1 possesses a two‐dimensional wave‐like structure, formed from a zigzag one‐dimensional chain, and 2 is a three‐dimensional network structure formed from a one‐dimensional chain and a pz bridging ligand. The temperature‐dependent magnetic behavior of 1 was studied.