Water-soluble Self-assembled {Pd84}Ac Polyoxopalladate Nano-wheel as a Supramolecular Host

Polyoxopalladates (POPs) are a class of self-assembling palladium-oxide clusters that span a variety of sizes, shapes and compositions. The largest of this family, {Pd₈₄}^Ac, is constructed from 14 building units of {Pd₆} and lined on the inner and outer torus by 28 acetate ligands. Due to its high water solubility, large hydrophobic cavity and distinct ¹H NMR fingerprint {Pd₈₄}^Ac is an ideal molecule for exploring supramolecular behaviour with small organic molecules in aqueous media. Molecular visualisation studies highlighted potential binding sites between {Pd₈₄}^Ac and these species. Nuclear Magnetic Resonance (NMR) techniques, including ¹H NMR, ¹H Diffusion Ordered Spectroscopy (DOSY) and Nuclear Overhauser Spectroscopy (NOESY), were employed to study the supramolecular chemistry of this system. Here, we provide conclusive evidence that {Pd₈₄}^Ac forms a 1 : 7 host-guest complex with benzyl viologen (BV²⁺) in aqueous solution.     

Exploring the Symmetry,Structure, and Self‐Assembly Mechanism of a Gigantic Seven‐Fold Symmetric {Pd84} Wheel

The symmetry, structure and formation mechanism of the structurally self‐complementary { Pd₈₄ } = [Pd₈₄O₄₂(PO₄)₄₂(CH₃CO₂)₂₈]^70? wheel is explored. Not only does the symmetry give rise to a non‐closest packed structure, the mechanism of the wheel formation is proposed to depend on the delicate balance between reaction conditions. We achieve the resolution of gigantic polyoxopalladate species through electrophoresis and size‐exclusion chromatography, the latter has been used in conjunction with electrospray mass spectrometry to probe the formation of the ring, which was found to proceed by the stepwise aggregation of {Pd₆}^? = [Pd₆O₄(CH₃CO₂)₂(PO₄)₃Na_6?nH_n]^? building blocks. Furthermore, the higher‐order assembly of these clusters into hollow blackberry structures of around 50 nm has been observed using dynamic and static light scattering.     

Exploring the Symmetry,Structure, and Self‐Assembly Mechanism of a Gigantic Seven‐Fold Symmetric {Pd84} Wheel

The symmetry, structure and formation mechanism of the structurally self‐complementary { Pd₈₄ } = [Pd₈₄O₄₂(PO₄)₄₂(CH₃CO₂)₂₈]⁷⁰⁻ wheel is explored. Not only does the symmetry give rise to a non‐closest packed structure, the mechanism of the wheel formation is proposed to depend on the delicate balance between reaction conditions. We achieve the resolution of gigantic polyoxopalladate species through electrophoresis and size‐exclusion chromatography, the latter has been used in conjunction with electrospray mass spectrometry to probe the formation of the ring, which was found to proceed by the stepwise aggregation of {Pd₆}⁻ = [Pd₆O₄(CH₃CO₂)₂(PO₄)₃Na_6−nH_n]⁻ building blocks. Furthermore, the higher‐order assembly of these clusters into hollow blackberry structures of around 50 nm has been observed using dynamic and static light scattering.     

A {Nb6P2W12}‐Based Hexameric Manganese Cluster with Single‐Molecule Magnet Properties

By deliberately using a metastable polyanion [(NbO₂)₆P₂W₁₂O₅₆]^12? ( 1 ), which was formed in situ, we have discovered the unprecedented hexameric cluster {Mn₁₅(Nb₆P₂W₁₂O₆₂)₆} ( 2 ), in which the six polyanions [Nb₆P₂W₁₂O₆₁]^10? are alternately connected by four intriguing trinuclear {Mn^III₃} moieties and four {Mn^II} linkers. This discovery is the first in which the phosphoniobotungstate has been made accessible by using transition‐metal ions; furthermore, polyanion 2 represents the largest niobotungstate cluster reported to date. Analysis by means of electrospray ionization mass spectrometry (ESI‐MS ) provides insight into the self‐assembly process, and the peaks observed relate to the different charge states of the parent cluster, thus confirming the stability of 2 . In addition, magnetic‐susceptibility measurements reveal that each {Mn^III₃} subunit is a separate single‐molecule magnet (SMM). This discovery results from the exploration of the reverse effect of metastable polyanion 1 possessing high reactivity, thereby turning a disadvantage into an advantage. This finding could define a new synthetic strategy for the design and synthesis of magnetic polyoxometalate (POM) clusters.     

A (3,6)-connected metal-organic framework consisting of chair-like {Fe6} clusters and BTC linkers

A 2-D framework composed of a chair-like {Fe₆} cluster and BTC linkers, [Fe₆(BTC)₂(HCOO)₆(DMF)₆] (1, BTC?=?1,3,5-benzenetricarboxylate), has been synthesized under solvothermal conditions and characterized by elemental analysis, infrared spectroscopy, thermal gravimetric analysis, and single-crystal X-ray diffraction analysis. The {Fe₆} cluster contains six iron ions and six formate ligands, with each formate coordinating with three iron ions to construct the hexa-nuclear iron wheel. The {Fe₆} wheels are further connected via BTC ligands resulting in the first example of a 2-D framework based on {Fe₆} clusters and BTC linkers. A magnetic study indicates that intramolecular antiferromagnetic interactions exist in the hexa-nuclear iron cluster.     

Discrete Silver(I)‐Palladium(II)‐Oxo Nanoclusters, {Ag4Pd13} and {Ag5Pd15}, and the Role of Metal–Metal Bonding Induced by Cation Confinement

We introduce the class of discrete silver(I)‐palladium(II)‐oxo nanoclusters with the preparation of {Ag₄Pd₁₃} and {Ag₅Pd₁₅}. Both polyanions represent the first examples of noble metal‐capped polyoxo‐noble‐metalates in a fully inorganic assembly, featuring an unprecedented host–guest mode containing hetero‐ and homometallic Ag–Pd and Ag–Ag bonding interactions. Comprehensive theoretical calculations suggest that the Ag–Pd metallic bonds originate partially from surface confinement of Ag^I guest ions onto the anionic polyoxopalladate host that is induced by strong electrostatic forces. This work opens the field of fully inorganic silver‐palladium‐oxo nanoclusters, which can be considered as discrete mixed noble metal precursors for the formation of monodisperse core–shell nanoparticles, with high relevance for catalysis.     

Large Hexadecametallic {MnIII–LnIII} Wheels: Synthesis,Structural, Magnetic,and Theoretical Characterization

The synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {Mn^III₈Ln^III₈} (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH₂, in the presence of ortho‐toluic or benzoic acid are reported. From the seven wheels studied the {Mn₈Dy₈} and {Mn₈Y₈} analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn₈Y₈} complex due to weak ferromagnetic Mn^III–Mn^III interactions. Ab initio CASSCF+RASSI‐SO calculations on the {Mn₈Dy₈} wheel estimated the Mn^III–Dy^III exchange interaction as ?0.1 cm^?1. This weak exchange along with unfavorable single‐ion anisotropy of Dy^III/Mn^III ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g‐anisotropy of the Dy^III ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn₈Ln₈} clusters reported here are the largest heterometallic Mn^IIILn^III wheels and the largest {3d–4f} wheels to exhibit SMM behavior reported to date.     

Structural characterization of the derivatives of bis{[2,6‐(dimethylamino)methyl]phenyl} selenide with palladium(II) and mercury(II)

The intramolecularly coordinated homoleptic diorgano selenide bis{2,6‐bis[(dimethylamino)methyl]phenyl} selenide, C₂₄H₃₈N₄Se or R₂Se, where R is 2,6‐(Me₂NCH₂)₂C₆H₃, 14 , was synthesized and its ligation reactions with Pd^II and Hg^II precursors were explored. The reaction of 14 with SO₂Cl₂ and K₂PdCl₄ resulted in the formation of the meta C—H‐activated dipalladated complex {μ‐2,2′‐bis[(dimethylamino)methyl]‐4,4′‐bis[(dimethylazaniumyl)methyl]‐3,3′‐selanediyldiphenyl‐κ⁴C¹,N²:C^1′,N^2′}bis[dichloridopalladium(II)], [Pd₂Cl₄(C₂₄H₃₈N₄Se)] or [{R(H)PdCl₂}₂Se], 15 . On the other hand, when ligand 14 was reacted with HgCl₂, the reaction afforded a dimercurated selenolate complex, {μ‐bis{2,6‐bis[(dimethylamino)methyl]benzeneselanolato‐κ⁴N²,Se:Se,N⁶}‐μ‐chlorido‐bis[chloridomercury(II)], [Hg₂(C₁₂H₁₉N₂Se)Cl₃] or RSeHg₂Cl₃, 16 , where two Hg^II ions are bridged by selenolate and chloride ligands. In palladium complex 15 , there are two molecules located on crystallographic twofold axes and within each molecule the Pd moieties are related by symmetry, but there are still two independent Pd centers. Mercury complex 16 results from the cleavage of one of the Se—C bonds to form a bifurcated SeHg₂ moiety with the formal charge on the Se atom being ?1. In addition, one of the Cl ligands bridges the two Hg atoms and there are two terminal Hg—Cl bonds. Each Hg atom is in a distorted environment which can be best described as a T‐shaped base with the bridging Cl atom in an apical position, with several angles close to 90° and with one angle much larger and closer to 180°.     

Benign synthesis of quinolinecarboxamide ligands,H2bqbenzo and H2bqb and their Pd(II) complexes: X-ray crystal structure,electrochemical and antibacterial studies

Two carboxamide ligands, H₂bqbenzo {3,4-bis(2-quinolinecarboxamido)benzophenone} and H₂bqb {N,N′-bis[(2-quinolinecarboxamide)-1,2-benzene]}, have been prepared using tetrabutylammonium bromide as an environmentally benign reaction medium. Two new Pd(II) complexes, [Pd^II(bqbenzo)] (1) and [Pd^II(bqb)] (2), have been synthesized, characterized, and their structures determined by single crystal X-ray diffraction. The di-anionic ligands, bqbenzo^2? and bqb^2?, are coordinated via two N_amide atoms and the nitrogens of the two quinoline rings, with Pd?N_amide < Pd–N_quinoline bond lengths. The geometry around palladium(II) in both complexes is distorted square planar. The electrochemical behaviors of the ligands and their Pd(II) complexes have been investigated by cyclic voltammetry in DMF. An irreversible Pd^II/I reduction is observed at ?1.06 V for 1 and at ?1.177 V for 2, indicating the influence of the R substituent on the central phenyl ring of carboxamide ligands on the Pd^II/I reduction potential. The ligands and palladium complexes were also screened for in vitro antibacterial activity. The Pd(II) complexes show strong biological activity against S.typhi and E.coli as Gram ?ve and B.cereus and S.aureus as Gram +ve bacteria comparable to the antibiotic penicillin. The antibacterial results also reveal that coordination of Pd(II) significantly improves the activity.     

A high-nuclear carbonylphosphine cluster of palladium,Pd23(CO)22(PEt3)10

Reactions of palladium derivatives in combination with phosphine ligands make possible the production of new species of high nuclearity. Here both the production and further characterization of a new high-nuclear cluster, Pd₂₃(CO)₂₂(PEt₃)₁₀ is described.     

Self‐Templating and In Situ Assembly of a Cubic Cluster‐of‐Clusters Architecture Based on a {Mo24Fe12} Inorganic Macrocycle

Engineering self‐templating inorganic architectures is critical for the development of bottom‐up approaches to nanoscience, but systems with a hierarchy of templates are elusive. Herein we describe that the cluster‐anion‐templated (CAT) assembly of a {CAT}?{Mo₂₄Fe₁₂} macrocycle forms a giant ca. 220 nm³ unit cell containing 16 macrocycles clustered into eight face‐shared tetrahedral cluster‐of‐clusters assemblies. We show that {CAT}?{Mo₂₄Fe₁₂} with different CATs gives the compounds 1 – 4 for CAT=Anderson {FeMo₆} ( 1 ), Keggin {PMo₁₂} ( 2 ), Dawson {P₂W₁₈} ( 3 ), and {Mo₁₂O₃₆(HPO₃)₂} ( 4 ) polyoxometalates. “Template‐free” assembly can be achieved, whereby the macrocycle components can also form a template in situ allowing template to macrocycle to superstructure formation and the ability to exchange the templates. Furthermore, the transformation of template clusters within the inorganic macrocycle {Mo₂₄Fe₁₂} allows the self‐generation of an uncapped {Mo₁₂O₃₆(HPO₃)₂} in compound 4 .     

Fine Tunable,Redox Active Octapalladium Chains Supported by Linear Tetraphosphines,Leading to Dynamically 1D Self-Assembled Coordination Polymers

A series of the octapalladium chains supported by meso-Ph₂PCH₂P(Ph)CH₂P(Ph)CH₂PPh₂ (meso-dpmppm) ligands, [Pd₈(meso-dpmppm)₄(L)₂](BF₄)₄ (L=none ( 1 ), solvents: CH₃CN ( 2 a ), dmf ( 2 b ), dmso ( 2 c ), RN≡C: R=Xyl ( 3 a ), Mes ( 3 b ), Dip ( 3 c ), ^tBu ( 3 d ), Cy ( 3 e ), CH₃(CH₂)₇ ( 3 f ), CH₃(CH₂)₁₁ ( 3 g ), CH₃(CH₂)₁₇ ( 3 h )) and [Pd₈(meso-dpmppm)₄(X)₂](BF₄)₂ (X=Cl ( 4 a ), N₃ ( 4 b ), CN ( 4 c ), SCN ( 4 d )), were synthesized by using 2 a as a stable good precursor, and characterized by spectroscopic (IR, ¹H and ³¹P NMR, UV-vis-NIR, ESI-MS) measurements and X-ray crystallographic analyses (for 1 , 2 a , b , 3 a , b , e , f , 4 a – d ). On the basis of DFT calculations on the X-ray determined structure of 2 b ( [2b-Pd₈]⁴⁺ ) and the optimized models [Pd₈(meso-Ph₂PCH₂P(H)CH₂P(H)CH₂PH₂)₄(CH₃CN)₂]⁴⁺ ( [Pd₈Ph₈]⁴⁺ ) and [Pd₈(meso-H₂PCH₂P(H)CH₂P(H)CH₂PH₂)₄(CH₃CN)₂]⁴⁺ ( [Pd₈H₈]⁴⁺ ), with and without empirically calculating dispersion force stabilization energy (B3LYP-D3, B3LYP), the formation energy between the two Pd₄ fragments is assumed to involve mainly noncovalent interactions (ca. −70 kcal/mol) with four sets of interligand C−H/π interactions and Pd⋅⋅⋅Pd metallophilic one, while electron shared covalent interactions are almost canceled out within the Pd₈ chain. All the compounds isolated are stable in solution and exhibit characteristic absorption at ∼900 nm, which is assignable to a spin allowed HOMO to LUMO transition, and shows temperature dependent intensity change with variable absorption coefficients presumably due to coupling with some thermal vibrations. The structures and electronic states of the Pd₈ chains are found finely tunable by varying the terminal capping ligands. In particular, theoretical calculations elucidated that the HOMO-LUMO energy gap is systematically related to the central Pd−Pd distance (2.7319(6)–2.7575(6) Å) by two ways with neutral ligands L ( 1 , 2 , 3 ) and with anionic ligands X ( 4 ), which are reflected on the NIR absorption energy of 867–954 nm. The isocyanide terminated Pd₈ complexes ( 3 ) further reacted with excess of RNC (6 eq) to afford the Pd₄ complexes, [Pd₄(meso-dpmppm)₂(RNC)₂](BF₄)₂ ( 13 ), and the cyclic voltammograms of 2 a (L=CH₃CN), 3 , and 13 (R=Xyl, Mes, ^tBu, Cy) demonstrated wide range redox behaviors from 2{Pd₄}⁴⁺ to 2{Pd₄}⁰ through 2{Pd₄}²⁺↔{Pd₈}⁴⁺, {Pd₈}³⁺, and {Pd₈}²⁺ strings. The oxidized complexes, [Pd₄(meso-dpmppm)₂(RNC)₃](BF₄)₄ ( 16 ), were characterized by X-ray analyses, and the two-electron reduced chain of [Pd₈(meso-dpmppm)₄](BF₄)₂ ( 7 ) was analyzed by spectroscopic and electrochemical techniques and DFT calculations. Reactions of 2 a with 1 equiv. of aromatic linear bisisocyanide (BI) in CH₂Cl₂ deposited insoluble coordination polymers, {[Pd₈(meso-dpmppm)₄(BI)](BF₄)₄}_n ( 5 ), and interestingly, they were soluble in acetonitrile, ³¹P{¹H} and ¹H DOSY NMR spectra as well as SAXS curves suggesting that the coordination polymers may exist in acetonitrile as dynamically 1D self-assembled coordination polymers comprising ca. 50 units of the Pd₈ rod averaged within the timescale.     

From Small {Mo2O4}2+ Aggregates to Infinite Solids

Mononuclear oxohalomolybdates(V) readily generate in the mixtures of alcohols and pyridines through a series of substitution and dimerization reactions, still reactive dinuclear {Mo₂O₄}²⁺ fragments which assemble together into larger cluster species. In all, the {Mo₂O₄}²⁺ unit with the two molybdenum atoms connected by a single metal-metal bond, appears as a recurrent structural motif, either as a single {Mo₂O₄}²⁺ unit in dinuclear compounds or as assemblies of two, three, four or six units through bridging oxygen donor ligands in tetranuclear, hexanuclear, octanuclear and dodecanuclear compounds, respectively. Pyridine, halide, alkoxide and alcohol ligands occupy the peripheral positions of the molybdenum oxide cores. Their structures will be presented in terms of different arrangements and connectivities among the basic dinuclear building blocks. By using a suitable linker, an oxalate adopting a bisbidentate binding mode was shown to serve the purpose, the {Mo₂O₄}²⁺ units were connected into infinite chains.     

Isotope and Hydrogen-Bond Effects on the Self-Assembly of Macroions in Dilute Solution

We report on the disparity in the assembly behavior of four types of nano-sized macroions induced by isotopic substitution of protium (H) to deuterium (D) in solvents. Macroions with modest charge density can self-assemble into single-layer, hollow, spherical “blackberry”-type structures, with larger assembly sizes representing stronger attractions among the macroions. Kinetically, all assembly processes become slower in D₂O than in H₂O. Thermodynamically, the polyoxometalate {SrPd₁₂}, the uranium cage {U₆₀} with alkali metal counterions, and the metal–organic cationic cage {Pd₁₂L₂₄} demonstrate similar assembly sizes in both H₂O and D₂O, whereas the metal oxide cluster {Mo₇₂Fe₃₀} as a weak acid shows an unusually large assembly size in H₂O—suggesting a stronger contribution from the hydrogen bonding in the last case.     

Enhanced π‐back‐donation resulting in the trans labilization of a pyridine ligand in an N‐heterocyclic carbene (NHC) PdII precatalyst: a case study

The molecular structure of the benzimidazol‐2‐ylidene–PdCl₂–pyridine‐type PEPPSI (pyridine‐enhanced precatalyst, preparation, stabilization and initiation) complex {1,3‐bis[2‐(diisopropylamino)ethyl]benzimidazol‐2‐ylidene‐κC²}dichlorido(pyridine‐κN)palladium(II), [PdCl₂(C₅H₅N)(C₂₃H₄₀N₄)], has been characterized by elemental analysis, IR and NMR spectroscopy, and natural bond orbital (NBO) and charge decomposition analysis (CDA). Cambridge Structural Database (CSD) searches were used to understand the structural characteristics of the PEPPSI complexes in comparison with the usual N‐heterocyclic carbene (NHC) complexes. The presence of weak C—H…Cl‐type hydrogen‐bond and π–π stacking interactions between benzene rings were verified using NCI plots and Hirshfeld surface analysis. The preferred method in the CDA of PEPPSI complexes is to separate their geometries into only two fragments, i.e. the bulky NHC ligand and the remaining fragment. In this study, the geometry of the PEPPSI complex is separated into five fragments, namely benzimidazol‐2‐ylidene (Bimy), two chlorides, pyridine (Py) and the Pd^II ion. Thus, the individual roles of the Pd atom and the Py ligand in the donation and back‐donation mechanisms have been clearly revealed. The NHC ligand in the PEPPSI complex in this study acts as a strong σ‐donor with a considerable amount of π‐back‐donation from Pd to C_carbene. The electron‐poor character of Pd^II is supported by π‐back‐donation from the Pd centre and the weakness of the Pd—N(Py) bond. According to CSD searches, Bimy ligands in PEPPSI complexes have a stronger σ‐donating ability than imidazol‐2‐ylidene ligands in PEPPSI complexes.     

Pincer‐Type Heck Catalysts and Mechanisms Based on PdIV Intermediates: A Computational Study

Pincer‐type palladium complexes are among the most active Heck catalysts. Due to their exceptionally high thermal stability and the fact that they contain Pd^II centers, controversial Pd^II/Pd^IV cycles have been often proposed as potential catalytic mechanisms. However, pincer‐type Pd^IV intermediates have never been experimentally observed, and computational studies to support the proposed Pd^II/Pd^IV mechanisms with pincer‐type catalysts have never been carried out. In this computational study the feasibility of potential catalytic cycles involving Pd^IV intermediates was explored. Density functional calculations were performed on experimentally applied aminophosphine‐, phosphine‐, and phosphite‐based pincer‐type Heck catalysts with styrene and phenyl bromide as substrates and (E)‐stilbene as coupling product. The potential‐energy surfaces were calculated in dimethylformamide (DMF) as solvent and demonstrate that Pd^II/Pd^IV mechanisms are thermally accessible and thus a true alternative to formation of palladium nanoparticles. Initial reaction steps of the lowest energy path of the catalytic cycle of the Heck reaction include dissociation of the chloride ligands from the neutral pincer complexes [{2,6‐C₆H₃(XPR₂)₂}Pd(Cl)] [X=NH, R=piperidinyl ( 1 a ); X=O, R=piperidinyl ( 1 b ); X=O, R=iPr ( 1 c ); X=CH₂, R=iPr ( 1 d )] to yield cationic, three‐coordinate, T‐shaped 14e^? palladium intermediates of type [{2,6‐C₆H₃(XPR₂)₂}Pd]⁺ ( 2 ). An alternative reaction path to generate complexes of type 2 (relevant for electron‐poor pincer complexes) includes initial coordination of styrene to 1 to yield styrene adducts [{2,6‐C₆H₃(XPR₂)₂}Pd(Cl)(CH₂?CHPh)] ( 4 ) and consecutive dissociation of the chloride ligand to yield cationic square‐planar styrene complexes [{2,6‐C₆H₃(XPR₂)₂}Pd(CH₂?CHPh)]⁺ ( 6 ) and styrene. Cationic styrene adducts of type 6 were additionally found to be the resting states of the catalytic reaction. However, oxidative addition of phenyl bromide to 2 result in pentacoordinate Pd^IV complexes of type [{2,6‐C₆H₃(XPR₂)₂}Pd(Br)(C₆H₅)]⁺ ( 11 ), which subsequently coordinate styrene (in trans position relative to the phenyl unit of the pincer cores) to yield hexacoordinate phenyl styrene complexes [{2,6‐C₆H₃(XPR₂)₂}Pd(Br)(C₆H₅)(CH₂?CHPh)]⁺ ( 12 ). Migration of the phenyl ligand to the olefinic bond gives cationic, pentacoordinate phenylethenyl complexes [{2,6‐C₆H₃(XPR₂)₂}Pd(Br)(CHPhCH₂Ph)]⁺ ( 13 ). Subsequent β‐hydride elimination induces direct HBr liberation to yield cationic, square‐planar (E)‐stilbene complexes with general formula [{2,6‐C₆H₃(XPR₂)₂}Pd(CHPh?CHPh)]⁺ ( 14 ). Subsequent liberation of (E)‐stilbene closes the catalytic cycle.     

anti-Bis(μ-2-ammonio­ethane­thiol­ato-κ2S:S)­bis­[di­chloro­palladium(II)] dihydrate

Each of two square-planar Pd^II ions in the title compound, [Pd₂Cl₄(μ-Haet-S)₂]·2H₂O (Haet = 2-ammonio­ethane­thiol­ate, C₂H₇NS), which was obtained by rearrangement of [Pd₂{Pd(aet-N,S)₂}₄]⁴⁺ in acidic solution, is coordinated by two bridging S atoms from two Haet ligands and by two terminal Cl atoms, forming the dinuclear structure. Since the complex is situated on a center of symmetry, the two monodentate Haet arms are located on opposite sides of the central Pd₂S₂ square plane, i.e. the present complex is the anti isomer. The S—C—C—N torsion angle is 177.3 (6)° and some intermolecular hydrogen bonds are observed.     

Cyanide Complexes Based on {Mo6I8}4+ and {W6I8}4+ Cluster Cores

Compounds based on new cyanide cluster anions [{Mo₆I₈}(CN)₆]^2–, trans-[{Mo₆I₈}(CN)₄(MeO)₂]^2– and trans-[{W₆I₈}(CN)₂(MeO)₄]²⁻ were synthesized using mechanochemical or solvothermal synthesis. The crystal and electronic structures as well as spectroscopic properties of the anions were investigated. It was found that the new compounds exhibit red luminescence upon excitation by UV light in the solid state and solutions, as other cluster complexes based on {Mo₆I₈}⁴⁺ and {W₆I₈}⁴⁺ cores do. The compounds can be recrystallized from aqueous methanol solutions; besides this, it was shown using NMR and UV-Vis spectroscopy that anions did not undergo hydrolysis in the solutions for a long time. These facts indicate that hydrolytic stabilization of {Mo₆I₈} and {W₆I₈} cluster cores can be achieved by coordination of cyanide ligands.     

Exploring the Molecular Growth of Two Gigantic Half‐Closed Polyoxometalate Clusters {Mo180} and {Mo130Ce6}

Understanding the process of the self‐assembly of gigantic polyoxometalates and their subsequent molecular growth, by the addition of capping moieties onto the oxo‐frameworks, is critical for the development of the designed assembly of complex high‐nuclearity cluster species, yet such processes remain far from being understood. Herein we describe the molecular growth from {Mo₁₅₀} and {Mo₁₂₀Ce₆} to afford two half‐closed gigantic molybdenum blue clusters {Mo₁₈₀} ( 1 ) and {Mo₁₃₀Ce₆} ( 2 ), respectively. Compound 1 features a hat‐shaped structure with the parent wheel‐shaped {Mo₁₅₀} being capped by a {Mo₃₀} unit on one side. Similarly, 2 exhibits an elliptical lanthanide‐doped wheel {Mo₁₂₀Ce₆} that is sealed by a {Mo₁₀} unit on one side. Moreover, the observation of the parent uncapped {Mo₁₅₀} and {Mo₁₂₀Ce₆} clusters as minor products during the synthesis of 1 and 2 strongly suggests that the molecular growth process can be initialized from {Mo₁₅₀} and {Mo₁₂₀Ce₆} in solution, respectively.     

Anionische Nickel-Pseudohalogenid-Komplexe der Typen [Ni{N(CN)2}3]− und [Ni{N(CN)2}2(NCS)2]2−

Anionie Nickel Pseudohalide Complexes of the Types [Ni{N(CN)₂}₃]^? and [Ni{N(CN)₂}₂(NCS)₂]^2? The preparation of a new type of anionic pseudohalide complexes of nickel [Ni{N(CN)₂}₃]^? and of mixed thiocyanate-dicyanamide complexes [Ni{N(CN)₂}₂(NCS)₂]^2? is reported. The structures of the complexes are discussed on the basis of IR- and magnetic measurements. The new compounds are representing polymer octahedral complexes with a bridging function of the dicyanamide ligands.