In Situ Metal-Assisted Ligand Modification Induces Mn4 Cluster-to-Cluster Transformation: A Crystallography,Mass Spectrometry,and DFT Study

Dehydration of (S,S)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethane-1,2-diol (H₄L) to (Z)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethenol) (H₃L′) was found to be metal-assisted, occurs under solvothermal conditions (H₂O/CH₃OH), and leads to [Mn^II₄(H₃L)₄Cl₂]Cl₂ ⋅ 5 H₂O ⋅ 5 CH₃OH ( Mn₄L₄ ) and [Mn^II₄(H₂L′)₆(μ₃-OH)]Cl ⋅ 4 CH₃OH ⋅ H₂O ( Mn₄L′₆ ), respectively. Their structures were determined by single-crystal XRD. Extensive ESI-MS studies on solutions and solids of the reaction led to the proposal consisting of an initial stepwise assembly of Mn₄L₄ from the reactants via [MnL] and [Mn₂L₂] below 80 °C, and then disassembly to [MnL] and [MnL₂] followed by ligand modification before reassembly to Mn₄L′₆ via [MnL′], [MnL′₂], and [Mn₂L′₃] with increasing solvothermal temperature up to 140 °C. Identification of intermediates [Mn₄L_xL′_6−x] (x=5, 4, 3, 2, 1) in the process further suggested an assembly/disassembly/in situ reaction/reassembly transformation mechanism. These results not only reveal that multiple phase transformations are possible even though they were not realized in the crystalline state, but also help to better understand the complex transformation process between coordination clusters during “black-box” reactions.     

Slow Magnetic Relaxation,Antiferromagnetic Ordering,and Metamagnetism in MnII(H2dapsc)-FeIII(CN)6 Chain Complex with Highly Anisotropic Fe-CN-Mn Spin Coupling

Reactions of [Mn(H₂dapsc)Cl₂] ⋅ H₂O (dapsc=2,6- diacetylpyridine bis(semicarbazone)) with K₃[Fe(CN)₆] and (PPh₄)₃[Fe(CN)₆] lead to the formation of the chain polymeric complex {[Mn(H₂dapsc)][Fe(CN)₆][K(H₂O)_3.5]}_n ⋅ 1.5n H₂O ( 1 ) and the discrete pentanuclear complex {[Mn(H₂dapsc)]₃[Fe(CN)₆]₂(H₂O)₂} ⋅ 4 CH₃OH ⋅ 3.4 H₂O ( 2 ), respectively. In the crystal structure of 1 the high-spin [Mn^II(H₂dapsc)]²⁺ cations and low-spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano-bridged chains. The K⁺ ions are located between the chains and are coordinated by oxygen atoms of the H₂dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency-dependent ac magnetic susceptibility, indicating single-chain magnetic behavior with a Mydosh-parameter φ=0.12 and an effective energy barrier (U_eff/k_B) of 36.0 K with τ₀=2.34×10⁻¹¹ s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra-chain spin coupling between [Fe^III(CN)₆]³⁻ and [Mn^II(H₂dapsc)]²⁺ units resulting from orbital degeneracy and unquenched orbital momentum of [Fe^III(CN)₆]³⁻ complexes. The origin of the metamagnetic transition is discussed in terms of strong magnetic anisotropy and weak AF interchain spin coupling.     

Polyoxometalate-Incorporated CuI-Resorcin[4]arene Metal-Organic Complexes as Heterogeneous Catalysts for Catalytic Oxidation of Mustard Gas Simulant

Exploring efficient heterogeneous catalysts for catalytic oxidation of chemical warfare agents (CWAs) is highly desired. As a class of discrete anionic metal oxide clusters, polyoxometalates (POMs) provide abundant catalytic active sites, thus resulting their rich redox properties. Here, a family of known POM-incorporated Cu^I-resorcin[4]arene metal-organic complexes, namely, [Cu₄(TPTR4A)₂][PW₁₂O₄₀](OH) ⋅ 0.5DMA ⋅ 5H₂O ( Cu - PW ), [Cu₄(TPTR4 A)₂][PMo₁₂O₄₀](OH) ⋅ 2DMA ⋅ H₂O ( Cu - PMo ) and [Cu₄(TPTR4A)₂][SiW₁₂O₄₀] ⋅ 2.5DMA ( Cu - SiW ) were utilized as catalysts to promote the oxidation of 2-chloroethyl ethyl sulfide (CEES). Strikingly, compared to the novel compound [Cu₃Cl₆(TPTR4A)(DMA)] ⋅ CH₃CH₂OH (defined as Cu - T ), the three complexes exhibited excellent stability, indicating that the integration of POMs and metal–organic units could improve the stability of the compounds. Moreover, Cu - PMo and Cu - PW showed higher activities for the catalytic oxidation of CEES to CEESO with selectivities both of 99 %.     

A Domino Fusion of an Organic Ligand Depended on Metal-Induced and Oxygen Insertion,Unraveled by Crystallography,Mass Spectrometry,and DFT Calculations

Herein, the reaction of (1-methyl-1 H-benzo[d]imidazol-2-yl)methanamine ( L1 ) with Co(H₂O)₆Cl₂, in CH₃CN at 120 °C, leading to the 2,3,5,6-tetrakis(1-methyl-1 H-benzo[d]imidazol-2-yl)pyrazine ( 3 ), isolated as a dimeric cluster {[Co^II₂( 3 )Cl₄] ⋅ 2 CH₃CN} ( 2 ), is reported. When O₂ and H₂O are present, (1-methyl-1 H-benzo[d]imidazole-2-carbonyl)amide (H L1′ ) is first formed and crystallized as [Co^III( L1 )₂( L1′ )]Cl₂ ⋅ 2 H₂O ( 4 ) before fusion of H L1′ with L1 , giving 1-methyl-N-(1-methyl-1 H-benzo[d]imidazol-2-carbonyl)-1 H-benzo[d]imidazol-2-carboxamide (H L2′′ ) forming a one-dimensional (1D) chain of [Co^II₃( L2′′ )₂Cl₄]_n ( 5 ). The combination of crystallography and mass spectrometry (ESI-MS) of isolated crystals and the solutions taken from the reaction as a function time reveal seven intermediate steps leading to 2 , but six steps for 5 , for which a different sequence takes place. Control and isotope labeling experiments confirm the two carbonyl oxygen atoms in 5 originate from both air and water. The dependence on the metals, compared with FeCl₃ ⋅ 6 H₂O leading to a stable triheteroarylmethyl radical, is quite astounding, which could be attributed to the different oxidation states of the metals and coordination modes confirmed by DFT calculations. This metal and valence dependent process is a very useful way for selectively obtaining these large molecules, which are unachievable by common organic synthesis.     

Structures of cerium manganese pivalates

The Ce,Mn mixed-metal polynuclear compounds [Ce ₃Mn₆(O)₅(OH)₃Piv₁₂Cl₂(THF)₃]·2THF, [Ce₃Mn₈(O)₈Piv₁₆Cl₂(HPiv)₂]·C₇H₁₆, [Ce₁₀Mn₄(O)₆(OH)₁₂Piv₁₆Cl₂(THF)₂]·2THF·2H₂O, [CeMn₁₁Cl₃(O)₈Piv₁₅(H₂O)]·CH₂Cl₂, and [CeMn₈(O)₈Piv₁₂(HPiv)₂(THF)₂] were prepared and structurally characterized. The possibility of synthesizing p,d,f-heterospin complexes by replacing coordinated THF molecules by nitroxide molecules was exemplified by the reaction of [Ce₃Mn₆(O)₅(OH)₃Piv₁₂Cl₂(THF)₃]·2THF with nitronyl nitroxides (NIT-R is 2-R-4,4,5,5-tetramethyl-24midazoline-l-oxyl 3-oxide; R is Me or 4-Py). The X-ray diffraction study of these complexes showed that [Ce₃Mn₆(O)₅(OH)₃Piv₁₂Cl₂(HPiv)(NIT-Me)₂] and [CeMn₈(O)₈Piv₁₂(NIT4-Py) ₄] · 2C₆H₁₄ have a molecular structure and [Ce₃Mn₆(O)₅(OH)₃-Piv₁₂Cl₂(NIT-Me)(H₂O)] is an infinite chain.     

Intrinsic Molybdenum-Based POMOFs with Impressive Gas Adsorptions and Photochromism

Novel molybdenum(VI/V) POM-based self-constructed frameworks [Mo^VI₁₂O₂₄(μ₂-O)₁₂(trz)₆(H₂O)₆] ⋅ 6Hma ⋅ 18H₂O ( 1 , Htrz=1H-1,2,3-triazole, ma=methylamine), [Mo^VI₇O₁₄(μ₂-O)₈(trz)₅(H₂O)] ⋅ 7Hma ⋅ 5H₂O ( 2 ), Na₃[Mo^V₆O₆(μ₂-O)₉(Htrz)₃(trz)₃] ⋅ 7.5H₂O ( 3 ) and [Mo^V₈O₈(μ₂-O)₁₂(Htrz)₈] ⋅ 30H₂O ( 4 ) have been covalently decorated with tri-coordinated deprotonated/protonated 1,2,3-triazoles. Channels with an inner diameter of 7.5 Å were found in 1 , whereas a tunnel composed of stacking molecules with an inner diameter of 4.1 Å along the b-axis exists in 2 ; it is occupied by free disordered methylamines, showing selective adsorption of O₂ and CO₂ at 25 °C. Obvious downfield shifts were observed by ¹³C NMR spectroscopies for methylamines inside the confined channels in 1 and 2 . There are diversified pores in 3 and 4 , which are formed by the molecules themselves and intermolecular accumulations. Adsorption tests indicate that 3 and 4 are fine adsorption materials for CH₄ and CO₂ under low pressure that rely on the environments built by the POMs. Correspondingly, 1 and 2 display reversible photoresponsive thermochromism that is subtlety influenced by the channels. The polyoxometalate organic frameworks (POMOFs) with multiple functional adsorptions are easy to assemble. Their photo-/thermoresponse properties offer a new pathway for the self-constructions of one-off hybrid materials that possess the good properties of both POMs and MOFs.     

Self-Assembly of Polyoxometalate-Resorcin[4]arene-Based Inorganic-Organic Complexes: Metal Ion Effects on the Electrochemical Performance of Lithium Ion Batteries

With their adjustable structures and diverse functions, polyoxometalate (POM)-resorcin[4]arene-based inorganic–organic complexes are a kind of potential multifunctional material. They have potential applications for lithium ion batteries (LIBs). However, the relationship between different coordinated metal ions and electrochemical performance has rarely been investigated. Here, three functionalized POM-resorcin[4]arene-based inorganic–organic materials, [Co₂(TMR4 A)₂(H₂O)₁₀][SiW₁₂O₄₀] ⋅ 2 EtOH ⋅ 4.5 H₂O ( 1 ), [Ni₂(TMR4 A)₂(H₂O)₁₀][SiW₁₂O₄₀] ⋅ 4 EtOH ⋅ 13 H₂O ( 2 ), and [Zn₂(TMR4 A)₂(H₂O)₁₀][SiW₁₂O₄₀] ⋅ 2 EtOH ⋅ 2 H₂O ( 3 ), have been synthesized. Furthermore, to enhance the conductivities of these compounds, 1–3 were doped with reduced graphene oxide (RGO) to give composites 1 @RGO- 3 @RGO, respectively. As anode materials for LIBs, 1 @RGO- 3 @RGO can deliver very high discharge capacities (1445.9, 1285.0 and 1095.3 mAh g⁻¹, respectively) in the initial run, and show discharge capacities of 898, 665 and 651 mAh g⁻¹, respectively, at a current density of 0.1 A g⁻¹ over 100 runs. More importantly, the discharge capacities of 319, 283 and 329 mAh g⁻¹ were maintained for 1 @RGO- 3 @RGO even after 400 cycles at large current density (1 A g⁻¹).     

New penta-nuclear and hepta-nuclear iron(II, III) complexes with ferrocenedicarboxylic acid

The reaction of [Fe₃EuO₂(O₂CCCl₃)₈(H₂O)(THF)₃] or [Fe₂CaO(O₂CCCl₃)₆(THF)₄] and [Fe₃O(O₂CCMe₃)₆(H₂O)₃]NO₃ with 1,1′-ferrocenedicarboxylic acid (fcdcH₂) yielded penta- and hepta-nuclear [Fe₄O₂(O₂CCCl₃)₆(fcdc)(THF)₂(H₂O)₂] and [Fe₆O₂(OH)₂(O₂CCMe₃)₁₀(fcdc)(H₂O)₂], respectively, which are the first X-ray structurally characterized clusters comprising Fe(III) and the ferrocenedicarboxylic organometallic ligand. Variable-temperature solid-state magnetic susceptibility measurements in the temperature range 1.8–300 K were carried out, and for both complexes a predominantly antiferromagnetic exchange interaction between the metal centres was observed. Mössbauer investigations show the presence of different environments for the Fe(III) atoms and confirm that no electron-transfer from Fe(II) of the ferrocene unit to Fe(III) of the central core occurs.     

Effect of Axial Ligands on Easy-Axis Anisotropy and Field-Induced Slow Magnetic Relaxation in Heptacoordinated FeII Complexes

A rational approach to modulating easy-axis magnetic anisotropy by varying the axial donor ligand in heptacoordinated Fe^II complexes has been explored. In this series of complexes with formulae of [Fe(H₄L)(NCS)₂] ⋅ 3 DMF ⋅ 0.5 H₂O ( 1 ), [Fe(H₄L)(NCSe)₂] ⋅ 3 DMF ⋅ 0.5 H₂O ( 2 ), and [Fe(H₄L)(NCNCN)₂] ⋅ DMF ⋅ H₂O ( 3 ) [H₄L=2,2′-{pyridine-2,6-diylbis(ethan-1-yl-1-ylidene)}bis(N-phenylhydrazinecarboxamide)], the axial positions are successively occupied by different nitrogen-based π-donor ligands. Detailed dc and ac magnetic susceptibility measurements reveal the existence of easy-axis magnetic anisotropy for all of the complexes, with 1 [U_eff=21 K, τ₀=1.72×10⁻⁶ s] and 2 [U_eff=25 K, τ₀=2.25×10⁻⁶ s] showing field-induced slow magnetic relaxation behavior. However, both experimental studies and theoretical calculations indicate the magnitude of the D value of complex 3 to be larger than those of complexes 1 and 2 due to the axial bond angle being smaller than that for an ideal geometry. Detailed analysis of the field and temperature dependences of relaxation time for 1 and 2 has revealed that multiple relaxation processes (quantum tunneling of magnetization, direct, and Raman) are involved in slow magnetic relaxation for both of these complexes. Magnetic dilution experiments support the role of intermolecular short contacts.     

Co(en)3[B4O5(OH)4]Cl·3H2O和[Ni(en)3][B5O6(OH)4]2·2H2O的合成、结构以及热力学性质

利用水热法合成了两种过渡金属配合物为模板剂的含水硼酸盐晶体Co(en)3[B4O5(OH)4]Cl·3H2O(1) 和 [Ni(en)3][B5O6(OH)4]2·2H2O (2),并通过元素分析、X射线单晶衍射、红外光谱及热重分析对其进行了表征。化合物1晶体结构的主要特点是在所有组成Co(en)33+, [B4O5(OH)4]2–, Cl– 和 H2O之间通过O–H…O、O–H…Cl、N–H…Cl和N–H…O四种氢键连接形成网状超分子结构。化合物2晶体结构的特点是[B5O6(OH)4]–阴离子通过O–H…O氢键连接形成沿a方向有较大通道的三维超分子骨架,模板剂[Ni(en)3]2+阳离子和结晶水分子填充在通道中。     

Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4-Amino-1,2,4-triazole

Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH₂-1,2,4-Triaz), 5-amino-tetrazole (5-NH₂-HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1 : 1 and 1 : 3 ratios with CeCl₃ ⋅ 7H₂O, [C₂mim]₃[CeCl₆] ([C₂mim]⁺=1-ethyl-2-methylimidazolium), and Ce(NO₃)₃ ⋅ 6H₂O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH₂-1,2,4-Triaz is structure directing via η²μ₂κ² bridging, with the formation of the dinuclear complexes [Ce₂Cl₂(μ₂-4-NH₂-1,2,4-Triaz)₄(H₂O)₈]Cl₄ ⋅ 4H₂O, [Ce₂(μ₂-4-NH₂-1,2,4-Triaz)₄(4-NH₂-1,2,4-Triaz)₂(Cl)₆], and [4-NH₂-1,2,4-HTriaz][Ce₂(μ₂-4-NH₂-1,2,4-Triaz)₂(μ₂-NO₃)(NO₃)₆(H₂O)₂]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce₆(μ₃-O)₄(μ₃-OH)₂(μ₃-Cl)₂(Cl)₆(μ₂-4-NH₂-1,2,4-Triaz)₁₂] ⋅ 7H₂O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M₆X₈ core, and the first reported Ce(III) hexanuclear complex of this type.     

Complexes based on the anionic octahedral rhenium chalcogenide clusters and [M(En)<Subscript>2</Subscript>]<Superscript>2+</Superscript> (M = Ni,Cu) cations

The compounds [Ni(H₂O)₂(En)₂][{Ni(En)₂}Re₆S₈(OH)₆] · 7H₂O (I), [{Cu(En)₂}Re₆S₈(H₂O)₂(OH)₄] · 4H₂O (II), and [Ni(H₂O)₂(En)₂]_0.5[Re₆Se₈(H₂O)₃(OH)₃] · 10H₂O (III) were synthesized by layering aqueous solutions of Ni(En)₂Cl₂ or Cu(En)₂Cl₂ (En is ethylenediamine) onto aqueous solutions of the potassium salts of the corresponding octahedral chalcohydroxo rhenium cluster complexes [Re₆Q₈(OH)₆]⁴⁻ (Q = S, Se). The structure of the obtained compounds was determined by X-ray diffraction analysis.     

New trans-[Re6S8(CN)4L2] n− Rhenium Cluster Complexes: Syntheses, Crystal Structures and Properties

Reaction of polymeric compound Cs₄[Re₆S₈(CN)₄S_2/2] with aqueous solution of KOH led to formation of trans-[Re₆S₈(CN)₄(OH)₂]⁴⁻ anion which was crystallized in ordered Cs_1.68K_2.32[Re₆S₈(CN)₄(OH)₂] · 2H₂O (1a) and disordered Cs_1.83K_2.17[Re₆S₈(CN)₄(OH)₂] · 2H₂O (1b) modifications. The presence of two types of apical ligands, inert cyanides and labile hydroxides, opened a way to other trans-[Re₆S₈(CN)₄L₂] ⁿ⁻ rhenium cluster complexes: trans-[Re₆S₈(CN)₄Cl₂]⁴⁻, trans-[Re₆S₈(CN)₄(H₂O)Br]³⁻, and trans-[Re₆S₈(CN)₄Br₂]⁴⁻, crystallized as Cs_1.84K_1.16(H)[Re₆S₈(CN)₄Cl₂] (2), Cs_1.68K_1.32[Re₆S₈(CN)₄(H₂O)Br] (3), (Me₄N)₃(H₅O₂)[Re₆S₈(CN)₄Br₂] (4), and CsK{Cu(H₂O)₂[Re₆S₈(CN)₄Cl₂]} · 4H₂O (5) salts.     

The bimolecular structure of aquahexa‐μ‐chlorido‐μ4‐oxido‐tris(tetrahydrofuran‐κO)tetracopper(II)–hexa‐μ‐chlorido‐μ4‐oxido‐tetrakis(tetrahydrofuran‐κO)tetracopper(II)–tetrahydrofuran (2/1/4)

The title bimolecular structure, [Cu₄Cl₆O(C₄H₈O)₃(H₂O)]₂[Cu₄Cl₆O(C₄H₈O)₄]·4C₄H₈O, at 100 K has monoclinic (P2₁/c) symmetry. The structure contains nine symmetry‐independent molecules expressed in simplest molecular form as 6[Cu₄Cl₆O(C₄H₈O)₃(H₂O)·2(C₄H₈O)]:3Cu₄Cl₆O(C₄H₈O)₄. The compound exhibits a supercell (smaller than the unit cell based on weak reflections) structure due to pseudotranslational symmetry. The structure displays O—H...O hydrogen bonding between bound water ligands and tetrahydrofuran (THF) solvent molecules. The structure exhibits disorder for 12 of the THF molecules, of which seven are ligated to Cu and five are hydrogen bonded to H₂O ligands.     

Bis(methanol‐κO)dioxido[3,3′‐(1H‐1,2,4‐triazole‐3,5‐diyl)diphenolato‐κ3O,N4,O′]uranium(VI) methanol monosolvate

The structure of the title compound, [U(C₁₄H₉N₃O₂)O₂(CH₃OH)₂]·CH₃OH, is the first to be reported for an actinide complex including triazole ligands. The U^VI atom exhibits a pentagonal–bipyramidal NO₆ coordination environment, involving two axial oxide ligands [U=O = 1.766 (3) and 1.789 (3) Å], four equatorial O atoms [U—O = 2.269 (3)–2.448 (3) Å] from the ligand and the two coordinated methanol molecules, and one equatorial N atom [U—N = 2.513 (4) Å] from the ligand. In the crystal structure, the complex molecules are linked via intermolecular N—H...O and O—H...O hydrogen bonds to form a two‐dimensional structure.     

Supramolecular Systems Based on Ca2+, [Mo3O2S2Cl6(H2O)3]2s-, [Mo3S4Cl6.75Br0.25(H2O)2]3s- and Cucurbit[6]uril

Adducts of cucurbit[6]uril with Ca²⁺ and trinuclear cluster chloroaquacomplexes (H₉O₄)₂(H₇O₃)₂[(Ca(H₂O)₅)2(C₃₆H₃₆N₂₄O₁₂)]Cl₈·0.67H₂O (1) and [(Ca(H₂O)₅)₂(C₃₆H₃₆N₂₄O₁₂)]× [Mo₃O₂S₂Cl₆(H₂O)₃]₂·13H₂O (2) are obtained and structurally characterized. The structures of both compounds contain polymeric [Ca(H₂O) _n ]₂² CB[6]∞ cations that form infinite columns; the space between them is filled with Cl^s- (1) and [Mo₃O₂S₂Cl₆(H₂O)₃]^2s- (2). A new (H₇O₃)₂(H₅O₂)× [Mo₃S₄Cl_6.25Br_0.25(H₂O)₂](C₃₆H₃₆N₂₄O₁₂)·CH₂Cl₂·6H₂O complex (3) is also obtained and structurally characterized.     

The Cocrystallization of the Cubic [Ta6Br12(H2O)6][CuBr2X2]·10H2O and Triclinic [Ta6Br12(H2O)6]X2·trans‐[Ta6Br12(OH)4(H2O)2]·18H2O (X = Cl,Br, NO3) Phases with the Coexistence of [Ta6Br12]2+ and [Ta6Br12]4+ in the Latter

Cubic [Ta₆Br₁₂(H₂O)₆][CuBr₂X₂]·10H₂O and triclinic [Ta₆Br₁₂(H₂O)₆]X₂·trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]·18H₂O (X = Cl, Br, NO₃) cocrystallize in aqueous solutions of [Ta₆Br₁₂]²⁺ in the presence of Cu²⁺ ions. The crystal structures of [Ta₆Br₁₂(H₂O)₆]Cl₂·trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]·18H₂O ( 1 ) and [Ta₆Br₁₂(H₂O)₆]Br₂·trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]·18H₂O ( 3 )have been solved in the triclinic space group P&1macr; (No. 2). Crystal data: 1 , a = 9.3264(2) Å, b = 9.8272(2) Å, c = 19.0158(4) Å, α = 80.931(1)?, β = 81.772(2)?, γ = 80.691(1)?; 3 , a = 9.3399(2) Å, b = 9.8796(2) Å, c = 19.0494(4) Å; α = 81.037(1)?, β = 81.808(1)?, γ = 80.736(1)?. 1 and 3 consist of two octahedral differently charged cluster entities, [Ta₆Br₁₂]²⁺ in the [Ta₆Br₁₂(H₂O)₆]²⁺ cation and [Ta₆Br₁₂]⁴⁺ in trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]. Average bond distances in the [Ta₆Br₁₂(H₂O)₆]²⁺ cations: 1 , Ta‐Ta, 2.9243 Å; Ta‐Brⁱ , 2.607 Å; Ta‐O, 2.23 Å; 3 , Ta‐Ta, 2.9162 Å; Ta‐Brⁱ , 2.603 Å; Ta‐O, 2.24 Å. Average bond distances in trans‐[Ta₆‐Br₁₂(OH)₄(H₂O)₂]: 1 , Ta‐Ta, 3.0133 Å; Ta‐Brⁱ, 2.586 Å; Ta‐O(OH), 2.14 Å; Ta‐O(H₂O), 2.258(9) Å; 3 , Ta‐Ta, 3.0113 Å; Ta‐Brⁱ, 2.580 Å; Ta‐O(OH), 2.11 Å; Ta‐O(H₂O), 2.23(1) Å. The crystal packing results in short O···O contacts along the c axes. Under the same experimental conditions, [Ta₆Cl₁₂]²⁺ oxidized to [Ta₆Cl₁₂]⁴⁺ , whereas [Nb₆X₁₂]²⁺ clusters were not affected by the Cu²⁺ ion.     

Crystal Structures and Raman Spectra of cis‐[SnCl4(H2O)2]·2H2O,cis‐[SnCl4(H2O)2]·3H2O, [Sn2Cl6(OH)2(H2O)2]·4H2O,and [HL][SnCl5(H2O)]·2.5H2O (L=3‐acetyl‐5‐benzyl‐1‐phenyl‐4, 5‐dihydro‐1, 2, 4‐triazine‐6‐one oxime,C18H18N4O2)

The complexes cis‐[SnCl₄(H₂O)₂]·2H₂O ( 1 ), [Sn₂Cl₆(OH)₂(H₂O)₂]·4H₂O ( 3 ), and [HL][SnCl₅(H₂O)]·2.5H₂O ( 4 ) were isolated from a CH₂Cl₂ solution of equimolar amounts of SnCl₄ and the ligand L (L=3‐acetyl‐5‐benzyl‐1‐phenyl‐4, 5‐dihydro‐1, 2, 4‐triazine‐6‐one oxime, C₁₈H₁₈N₄O₂) in the presence of moisture. 1 crystallizes in the monoclinic space group Cc with a = 2402.5(1) pm, b = 672.80(4) pm, c = 1162.93(6) pm, β = 93.787(6)° and Z = 8. 4 was found to crystallize monoclinic in the space group P2₁, with lattice parameters a = 967.38(5) pm, b = 1101.03(6) pm, c = 1258.11(6) pm, β = 98.826(6)° and Z = 2. The cell data for the reinvestigated structures are: [SnCl₄(H₂O)₂]·3H₂O ( 2 ): a = 1227.0(2) pm, b = 994.8(1) pm, c = 864.0(1) pm, β = 103.86(1)°, with space group C2/c and Z = 4; 3 : a = 961.54(16) pm, b = 646.29(7) pm, c = 1248.25(20) pm, β = 92.75(1)°, space group P2₁/c and Z = 4.     

The Effect of Guest Metal Ions on the Reduction Potentials of Uranium(VI) Complexes: Experimental and Theoretical Investigations

Two mononuclear uranyl complexes, [UO₂L¹] ( 1 ) and [UO₂L²] ⋅ 0.5 CH₃CN ⋅ 0.25 CH₃OH ( 2 ), have been synthesized from two multidentate N₃O₄ donor ligands, N,N′-bis(5-methoxysalicylidene)diethylenetriamine (H₂L¹) and N,N′-bis(3-methoxysalicylidene)diethylenetriamine (H₂L²), respectively, and have been structurally characterized. Both complexes 1 and 2 showed a reversible U^VI/U^V couple at −1.571 and −1.519 V, respectively, in cyclic voltammetry. The reduction potential of the U^VI/U^V couple shifted towards more positive potential on addition of Li⁺, Na⁺, K⁺, and Ag⁺ metal ions to acetonitrile solutions of complex 2 , and the resulting potential was correlated with the Lewis acidity of the metal ions and was also justified by theoretical DFT calculations. No such shift in reduction potential was observed for complex 1 . All four bimetallic products, [UO₂L²Li_0.5](ClO₄)_0.5 ( 3 ), [UO₂L²Na(ClO₄)]₂ ( 4 ), [UO₂L²Ag(NO₃)(H₂O)] ( 5 ), and [(UO₂L²)₂K(H₂O)₂]PF₆ ( 6 ), formed on addition of the Li⁺, Na⁺, Ag⁺, and K⁺ metal ions, respectively, to acetonitrile solutions of complex 2 , were isolated in the solid state and structurally characterized by single-crystal X-ray diffraction. In all the species, the inner N₃O₂ donor set of the ligand encompasses the equatorial plane of the uranyl ion and the outer open compartment with O₂O′₂ donor sites hosts the second metal ion.     

Hepta­aqua­tetra‐μ3‐hydroxy‐hexa‐μ2‐l‐leucine‐(l‐leucine)­tetraytterbium(III) tetrachlorozinc(II) tri­chloro­hydroxyzinc(II) tetrachloride octahydrate

The title bimetallic compound, [Yb₄(μ₃‐OH)₄(C₆H₁₃NO₂)₇(H₂O)₇][ZnCl₄][ZnCl₃(OH)]Cl₄·8H₂O, was synthesized at near physiological pH (6.0). The compound exhibits some novel structural features, including an asymmetric [Yb₄(μ₃‐OH)₄(l ‐leucine)₇(H₂O)₇]⁸⁺ complex cation in which four OH groups act as bridging ligands, linking four Yb³⁺ cations into a Yb₄O₄ structural unit. Each pair of adjacent Yb³⁺ ions is further bridged by one carboxy group from a leucine ligand. Water mol­ecules and a monodentate leucine ligand also coordinate to Yb³⁺ ions, completing their eight‐coordinate square‐antiprismatic coordination. The Yb₄(μ₃‐OH)₄(l ‐leu­cine)₇(H₂O)₇]⁸⁺ cation, the [ZnCl₄]²⁻, [ZnCl₃OH]²⁻ and Cl⁻ anions, and the lattice water mol­ecules are linked via hydrogen bonds.