A Sulfide (Selenide)-Centered Nonanuclear Silver Cluster: A Distorted and Flexible Tricapped Trigonal Prismatic Ag<Subscript>9</Subscript> Framework

Two luminescent, monoanionic chalcogenide-centered nonanuclear silver clusters stabilized by dichalcogenophosphates were synthesized and fully characterized by various spectroscopies including multinuclear NMR and ESI-mass. Single crystal X-ray diffraction studies on both cluster anions, [Ag₉(S){S₂P(OEt)₂}₈]^?, 1, and [Ag₉(Se){Se₂P(OEt)₂}₈]^?, 2, reveal that the nine silver atoms form an extremely distorted tricapped trigonal prism, which has an encapsulating chalcogenide. The coordination geometry of the central chalcogenide appears to be monocapped trigonal prismatic, which was analyzed by DFT calculations. The origin of the yellow emission is assigned by TDDFT calculations to originate from a chalcogen (ligand + encapsulated) → silver charge transfer.     

Reaction of S2CC(PPh3)2 with Silver Salts Containing Weakly Coordinating Anions; Preparation and Crystal Structures of [Ag6{S2CC(PPh3)2}4][BF4]6 · 9.75CH2CL2 and [Ag4{S2CC(PPh3)2}4][Al{OC(CF3)3}4]4 · 4.25C2H4Cl2

The betain‐like carbodiphosphorane CS₂ adduct S₂CC(PPh₃)₂ ( 1 ) reacts with Ag(I) salts which contain weakly coordinating anions such as [BF₄]^? or [Al{OC(CF₃)₃}₄]^? to produce the cluster compounds [Ag₆{S₂CC(PPh₃)₂}₄][BF₄]₆ ( 2 ) and [Ag₄{S₂CC(PPh₃)₂}₄][Al{OC(CF₃)₃}₄]₄ ( 3 ), respectively, as orange yellow crystals containing solvent molecules. In the solid state the Ag₄ unit in 3 forms a tetrahedron, and in the Ag₆ core of 2 two of the opposite edges of the tetrahedron are bridged by Ag⁺ ions. The clusters are held together by argentophilic interactions, and each sulfur atom of 1 is coordinated to four (as in 2 ) or three (as in 3 ) silver atoms. The compounds are characterized by IR and ³¹P NMR spectroscopic studies and by X‐ray diffraction analyses.     

Eight‐Electron Silver and Mixed Gold/Silver Nanoclusters Stabilized by Selenium Donor Ligands

The first atomically and structurally precise silver‐nanoclusters stabilized by Se‐donor ligands, [Ag₂₀{Se₂P(OⁱPr)₂}₁₂] ( 3 ) and [Ag₂₁{Se₂P(OEt)₂}₁₂]⁺( 4 ), were isolated by ligand replacement reaction of [Ag₂₀{S₂P(Oⁱ Pr)₂}₁₂] ( 1 ) and [Ag₂₁{S₂P(Oⁱ Pr)₂}₁₂]⁺ ( 2 ), respectively. Furthermore, doping reactions of 4 with Au(PPh₃)Cl resulted in the formation of [AuAg₂₀{Se₂P(OEt)₂}₁₂]⁺ ( 5 ). Structures of 3 , 4 , and 5 were determined by single‐crystal X‐ray diffraction. The anatomy of cluster 3 with an Ag₂₀ core having C ₃ symmetry is very similar to that of its dithiophosphate analogue 1 . Clusters 4 and 5 exhibit an Ag₂₁ and Au@Ag₂₀ core of O_h symmetry composed of eight silver capping atoms in a cubic arrangement and encapsulating an Ag₁₃ and Au@Ag₁₂ centered icosahedron, respectively. Both ligand exchange and heteroatom doping result in significant changes in optical and emissive properties for chalcogen‐passivated silver nanoparticles, which have been theoretically confirmed as 8‐electron superatoms.     

General Assembly of Twisted Trigonal‐Prismatic Nonanuclear Silver(I) Clusters

A general class of C₃‐symmetric Ag₉ clusters, [Ag₉S(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)] ( 1 ), [Ag₉(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)₂] ? CF₃SO₃ ( 2 ), [Ag₉(tBuC₆H₄S)₆(dpph)₃(NO₃)₂] ? NO₃ ( 3 ), and [Ag₉(tBuC₆H₄S)₇(dpph)₃(Mo₂O₇)_0.5]₂ ? 2 CF₃COO ( 4 ) (dpph=1,6‐bis(diphenylphosphino)hexane), with a twisted trigonal‐prism geometry was isolated by the reaction of polymeric {(HNEt₃)₂[Ag₁₀(tBuC₆H₄S)₁₂]}_n, 1,6‐bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag₉ twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S^2? and CF₃SO₃^? for compound 1 , 2×CF₃SO₃^? for compound 2 , 2×NO₃^? for compound 3 , and tBuC₆H₄S^? and Mo₂O₇^2? for compound 4 ). This trigonal prism is bisected by another shrunken Ag₃ trigon at its waist position. Interestingly, two inversion‐related Ag₉ trigonal‐prismatic clusters are dimerized by the Mo₂O₇^2? ion in compound 4 . The twist is amplified by the bulkier thiolate, which also introduces high steric‐hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver–sulfur clusters (namely, compounds 5 – 8 ) with their nuclearity ranging from 6–10 were solely characterized by single‐crystal X‐ray diffraction to verify the above‐described synergetic effect of mixed ligands in the construction of Ag₉ twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal‐centered (MC) d¹⁰→d⁹s¹ transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180–300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion‐ and surface‐controlled redox processes were determined for compounds 1 and 3 as well as compound 4 , respectively.     

Preparation of Hydride‐Ethylene Complexes of Osmium

Ethylene complexes [OsH(η²‐CH₂=CH₂)L₄]Y ( 1 , 2 ) [L = PPh(OEt)₂, P(OEt)₃; Y = OTf, BPh₄] were prepared by reacting the dihydride OsH₂L₄ first with methyl triflate CH₃OTf and then with ethylene (1 atm). Alternatively, the compound [OsH(η²‐CH₂=CH₂){PPh(OEt)₂}₄]OTf was prepared by allowing the dinitrogen derivative [OsH(N₂){PPh(OEt)₂}₄]OTf to react with ethylene. Acrylonitrile CH₂=C(H)CN reacts with OsH(OTf)L₄ [L = P(OEt)₃] to give the complex [OsH{κ¹‐NCC(H)=CH₂}{P(OEt)₃}₄]BPh₄ ( 3 ). The complexes were characterized spectroscopically (IR and ¹H, ¹³C, ³¹P NMR) and by X‐ray crystal structure determination of the [OsH(η²‐CH₂=CH₂){PPh(OEt)₂}₄]BPh₄ derivative.     

Beyond Clusters: Supramolecular Networks Self‐Assembled from Nanosized Silver Clusters and Inorganic Anions

Assembly of small clusters into rigid bodies with precise shape and symmetry has been witnessed by the significant advances in cluster‐based metal–organic frameworks (MOFs), however, nanosized silver cluster based MOFs remain largely unexplored. Herein, two anion‐templated silver clusters, CO₃@Ag₂₀ and SO₄@Ag₂₂, were ingeniously incorporated into a 2D sql lattice ( 1 , [CO₃@Ag₂₀(iPrS)₁₀(NO₃)₈(DMF)₂]_n) and an unprecedented 3D two‐fold interpenetrated dia network ( 2 , [SO₄@Ag₂₂(iPrS)₁₂(NO₃)₆ ? 2 NO₃]_n), respectively, under mild solvothermal conditions. Their atomically precise structures were confirmed by single‐crystal X‐ray diffraction analysis and further consolidated by IR spectroscopy, thermogravimetric analysis (TGA), and elemental analysis. Each drum‐like CO₃@Ag₂₀ cluster is extended by twelve NO₃^? ions to form the 2D sql lattice of 1 , whereas each ball‐shaped SO₄@Ag₂₂ cluster with a twisted truncated tetrahedral geometry is pillared by four [Ag₆(NO₃)₃] triangular prisms to form the 3D interpenetrated dia network of 2 . Notably, 2 is the first interpenetrated 3D MOF constructed from silver clusters. These results demonstrate the dual role of the anions, which not only internally act as anion templates to induce the formation of silver thiolate clusters but also externally extend the cluster units into the rigid networks. The photoluminescent and electrochemical properties of 2 are discussed in detail.     

Phosphor-1,1-Diselenolato Metal Complexes of Group 11 and 12

Abstract

Several copper and silver clusters containing diselenophosphate ligands such as tetranuclear [Cu{Se₂P(OR)₂}]₄, hexanuclear [Ag{Se₂P(OR)₂}]₆, octanuclear [Cu₈(μ₈-Se)}Se₂P(OR)₂}₆], [Ag₈(μ₈-Se)}Se₂P(OR)₂}₆], [Cu₈(μ₈-X)}Se₂P(OR)₂}₆](PF₆), [Ag₈(μ₈-X)}Se₂P(OR)₂}₆](PF₆), decanuclear [Ag₁₀(μ₁₀-Se)}Se₂P(OR)₂}₈], undecanuclear [Cu₁₁(μ₉-Se)(μ₃-X)₃}Se₂P(OR)₂}₆], [Ag₁₁(μ₉-Se)(μ₃-X)₃}Se₂P(OR)₂}₆], and dodecanuclear [Cu₁₂(P₂Se₆)}Se₂P(OR)₂}₈] have been isolated. All these clusters were well characterized in the solid-state and solution phase by elemental analysis, positive FAB mass spectrometry, multinuclear NMR (¹H, ³¹P, and ⁷⁷Se), and single crystal X-ray diffraction. In addition, tetranuclear zinc clusters [Zn₄(μ₄-Se){Se₂P(OPr)₂}₆], and [Zn₄(μ₄-O){Se₂P(OR)₂}₆] (R = Et, ⁱPr) also are synthesized and characterized. Solution studies of both [M{Se₂P(OEt)₂}₂]∞ and [M₂{Se₂P(OⁱPr)₂}₄] (M = Zn, Cd) which display a monomer-dimer equilibrium in solution were performed by VT ³¹P NMR in CD₂Cl₂.     

In situ synthesized homochiral dysprosium-oxo clusters with threonine Schiff bases

Chiral high-nuclearity lanthanide (4f) clusters have shown fantastic properties in various fields. However, their synthesis is still of great challenge. Herein, we report two pairs of enantiomers of high-nuclearity Dy-oxo clusters synthesized through in situ strategy. They are [Dy₁₈(^R/SHftp)₄ (^R/SH₂btp)₄(μ₂-OH)₈(μ₃-OH)₂₀(μ₆-O)(NO₃)₄(μ-H₂O)₈]·[solvents] (1R and 1S) and [Dy₉(^R/SHftp)₂ (^R/SH₂btp)₂(OAc)₆(μ₃-OH)₁₀(H₂O)₆](OAc)·[solvents] (2R and 2S), where ^R/SHftp²⁻ and ^R/SH₂btp³⁻ represent in situ formed 2-formyl-6-[N-(threonine)iminomethyl]-4-methylphenol and 2,6-bis[N-(threonine)iminomethyl]-4-methylphenol anions, respectively. These in situ formed clusters were endowed with not only homochirality via introducing ^R/SHftp²⁻ and ^R/SH₂btp³⁻ ligands, but also rich oxo-bridges by controlling the hydrolysis of Dy^III ions. Different anions from Dy^III salts further induced structural variation between two sets of clusters. 1R and 1S feature an unprecedent four-blade propeller shaped {Dy₁₈} core, whose centered octahedral {Dy₆} unit are surrounded by four triangular {Dy₃} units. Strikingly, they represent the second largest chiral 4f cluster species so far. 2R and 2S display a sandglass-like {Dy₉} skeleton that consist of two square pyramid {Dy₅} units sharing a Dy^III vertex. Magnetic investigation revealed possible antiferromagnetic interactions between the Dy^III centers in these clusters.     

The Unprecedented [S4N2O10]2− Anion in the Molecular Gold Complexes [Au2Br2(S4N2O10)2] and [Au2Cl2(S4N2O10)2](S2O5Cl2)

The reaction of hexachlorophosphazene, P₃N₃Cl₆, with SO₃ and the gold halides AuCl₃ and AuBr₃, respectively, leads to the new cyclic anionic tetramer, [S₄N₂O₁₀]²⁻, which is coordinated to Au³⁺ in the dimeric complexes [Au₂X₂(S₄N₂O₁₀)₂] (X=Cl, Br). The [S₄N₂O₁₀]²⁻ anion can be seen as the condensation product of two sulfate anions, [SO₄]²⁻_, and two amidosulfate anions, [NH₂SO₃]⁻.     

A New Synthetic Methodology in the Preparation of Bimetallic Chalcogenide Clusters via Cluster-to-Cluster Transformations

A decanuclear silver chalcogenide cluster, [Ag₁₀(Se){Se₂P(OⁱPr)₂}₈] (2) was isolated from a hydride-encapsulated silver diisopropyl diselenophosphates, [Ag₇(H){Se₂P(OⁱPr)₂}₆], under thermal condition. The time-dependent NMR spectroscopy showed that 2 was generated at the first three hours and the hydrido silver cluster was completely consumed after thirty-six hours. This method illustrated as cluster-to-cluster transformations can be applied to prepare selenide-centered decanuclear bimetallic clusters, [Cu_xAg_10-x(Se){Se₂P(OⁱPr)₂}₈] (x = 0–7, 3), via heating [Cu_xAg_7−x(H){Se₂P(OⁱPr)₂}₆] (x = 1–6) at 60 °C. Compositions of 3 were accurately confirmed by the ESI mass spectrometry. While the crystal 2 revealed two un-identical [Ag₁₀(Se){Se₂P(OⁱPr)₂}₈] structures in the asymmetric unit, a co-crystal of [Cu₃Ag₇(Se){Se₂P(OⁱPr)₂}₈]_0.6[Cu₄Ag₆(Se){Se₂P(OⁱPr)₂}₈]_0.4 ([3a]_0.6[3b]_0.4) was eventually characterized by single-crystal X-ray diffraction. Even though compositions of 2, [3a]_0.6[3b]_0.4 and the previous published [Ag₁₀(Se){Se₂P(OEt)₂}₈] (1) are quite similar (10 metals, 1 Se²⁻, 8 ligands), their metal core arrangements are completely different. These results show that different synthetic methods by using different starting reagents can affect the structure of the resulting products, leading to polymorphism.     

Nestlike Silver(I) Thiolate Clusters with Tunable Emission Color Templated by Heteroanions

Four silver thiolate clusters, [H₃O][(Ag₃S₃)(BF₄)@Ag₂₇(tBuS)₁₈(hfac)₆H₂O] ⋅ H₂O ( 1 ; hfac = hexafluoroacetylacetone), [(Ag₃S₃)(CF₃CO₂)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ CF₃CO₂ ⋅ 4 CH₃CN ( 2 ), [(Ag₃S₃)(MoO₄)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ 2 CH₃CN ( 3 ), and [(Ag₃S₃)(CrO₄)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ 4 CH₃CN ( 4 ), were isolated. They have similar nestlike structures assembled by an [Ag₃S₃]³⁻ template together with one of the BF₄⁻, CF₃CO₂⁻, MoO₄²⁻, or CrO₄²⁻ anions. Interestingly, the solid-state emissions of 2 – 4 are dependent on the templating anions and are tunable from green to orange and then to red by changing the template from CF₃CO₂⁻ to MoO₄²⁻ and to CrO₄²⁻, and this may be correlated to the charge transfer between these templates to metal atoms. This work helps to understand the templating role of heteroanions and the relationship between structure and properties.     

The influence of alkane spacer of bis(diphenylphosphino)alkanes on the nuclearity of silver(I): Syntheses and structures of P,P′-bridged clusters and coordination polymers involving dithiophosphates

The effect of the length of alkane spacer in diphosphines on the nuclearity of Ag(I) complexes containing dialkyl dithiophosphates (dtp) ligands has been investigated. 1,1-Bis(diphenylphosphino)methane (dppm) yielded tetranuclear [Ag₄(dppm)₂{S₂P(OEt)₂}₄] (1), [Ag₄(dppm)₂{S₂P(OⁱPr)₂}₄] (3), trinuclear [Ag₃(dppm)₃{S₂P(OEt)₂}₂](PF₆) (2), and a dinuclear [Ag₂(dppm)₂{S₂P(OⁱPr)}](PF₆) (4). The increase in spacer length from one methylene in dppm to two in 1,2-bis(diphenylphosphino)ethane (dppe) resulted in the formation of polymeric, [Ag(dppe){S₂P(OR)₂}]_∞ (R = Et, 5a and 5a′; ⁱPr, 5b), and [Ag₄(μ₃-Cl)(dppe)_1.5{S₂P(OR)₂}₃]_∞ (R = Et, 6a; ⁱPr, 6b). Compounds 5a, 5b, 6a and 6b were reported earlier [C.W. Liu, B.-J. Liaw, L.-S. Liou, J.-C. Wang, Chem. Commun. (2005) 1983]. Further increase in the chain length to four methylene units in 1,4-bis(diphenylphosphino)butane (dppb) yielded dppb-bridged polymers, [Ag(dppb){S₂P(OEt)₂}]_∞ (7) and [Ag₂(dppb){S₂P(OEt)₂}₂]_∞ (8). In all the polynuclear compounds, diphosphines acted as P,P′-bridging ligands, while the dtp ligands (S,S′-donors) adopted varieties of coordination patterns: S,S′-chelating (5, 7), S,S′-bridging (4), bimetallic-triconnective, μ₂:η²,η¹ (1, 3, 8), bimetallic-diconnective, μ₂:η² (2, 3) and trimetallic-triconnective, μ₃:η²,η¹ (6). Some of the complexes exhibit argentophilicity with Ag?Ag distances in the range, 2.918-3.360 Å. Concomitant bridging of two silver atoms either by dppm and dtp ligands (1, 3 and 4) or two dtp ligands (8) lead to close silver-silver contacts. The diphosphines (dppe and dppb) with longer spacer appeared to favor 1D or 2D polymers due to the flexibility of the spacer within the diphosphine unit by adopting anti conformation as opposed to syn conformation of the dppm linker is revealed in complexes.     

Münzmetallcluster mit verbrückenden Imido‐ und Amidoliganden: [{Li(dme)3}4][Cu18(NPh)11] und [Ag6(NHPh)4(PnPr3)6Cl2]

Copper and Silver Clusters with Bridging Imido and Amido Ligands From the reactions of copper and silver chloride with tertiary phosphines and lithiated aniline the compounds [{Li(dme)₃}₄][Cu₁₈(NPh)₁₁] ( 1 ) and [Ag₆(NHPh)₄(PⁿPr₃)₆Cl₂] ( 2 ) were obtained. The structure of the anion in 1 is closely related to the structures of the reported clusters [Cu₁₂(NPh)₈]^4– [1] and [Cu₂₄(NPh)₁₄]^4– [2]: 1 represents the third phenyl imido bridged copper cluster which contains parallel Cu₃‐ and Cu₆‐planes. The dimeric compound 2 consists of two Ag₃ units with bridging phenyl amido ligands. Two chloride and six phosphine ligands complete the ligand sphere and shield the metal core effectively.     

A novel three‐dimensional AgI coordination polymer based on mixed naphthalene‐1,5‐disulfonate and aminoacetate ligands

The three‐dimensional coordination polymer poly[[bis(μ₃‐2‐aminoacetato)di‐μ‐aqua‐μ₃‐(naphthalene‐1,5‐disulfonato)‐hexasilver(I)] dihydrate], {[Ag₆(C₁₀H₆O₆S₂)(C₂H₄NO₂)₄(H₂O)₂]·2H₂O}_n, based on mixed naphthalene‐1,5‐disulfonate (L1) and 2‐aminoacetate (L2) ligands, contains two Ag^I centres (Ag1 and Ag4) in general positions, and another two (Ag2 and Ag3) on inversion centres. Ag1 is five‐coordinated by three O atoms from one L1 anion, one L2 anion and one water molecule, one N atom from one L2 anion and one Ag^I cation in a distorted trigonal–bipyramidal coordination geometry. Ag2 is surrounded by four O atoms from two L2 anions and two water molecules, and two Ag^I cations in a slightly octahedral coordination geometry. Ag3 is four‐coordinated by two O atoms from two L2 anions and two Ag^I cations in a slightly distorted square geometry, while Ag4 is also four‐coordinated by two O atoms from one L1 and one L2 ligand, one N atom from another L2 anion, and one Ag^I cation, exhibiting a distorted tetrahedral coordination geometry. In the crystal structure, there are two one‐dimensional chains nearly perpendicular to one another (interchain angle = 87.0°). The chains are connected by water molecules to give a two‐dimensional layer, and the layers are further bridged by L1 anions to generate a novel three‐dimensional framework. Moreover, hydrogen‐bonding interactions consolidate the network.     

Two polymorphs of tetraethylammonium [hydrogen tris(3,5‐dimethylpyrazolyl)borato]di‐μ2‐sulfido‐disulfido(η2‐tetrasulfido)ditungsten(V) with Z′ = 1 and 2

Two polymorphs of the title compound, (C₈H₂₀N)[W₂S₄(S₄)(C₁₅H₂₂BN₆)], have been obtained unexpectedly by attempted recrystallization of a mixed‐metal–sulfur cluster complex from different solvents. The dinuclear complex anion contains W^V in two different coordination environments, one of them distorted octahedral with a tris(pyrazolyl)borate anion, a terminal sulfide and two bridging sulfide ligands, the other distorted square‐pyramidal with a terminal sulfide, two bridging sulfide and a chelating tetrasulfide ligand. The three independent anions in the two polymorphs have essentially the same geometry. The central W₂S₂ ring is a slightly folded rhombus with acute angles at the S atoms, and the WS₄ chelate ring is an envelope with one noncoordinating S atom as the flap. The second polymorph, with Z′ = 2 and pseudo‐inversion symmetry relating the anions of the asymmetric unit, also displays pseudo‐translation features in its layer structure, and all examined crystals were found to be twinned, possibly as a consequence of this structural feature.     

Silver(I) sulfate coordination polymers with 4,4′‐bipyridazine and pyridazino[4,5‐d]pyridazine

Poly[[μ₄‐4,4′‐bipyridazine‐μ₅‐sulfato‐disilver(I)] monohydrate], {[Ag₂(SO₄)(C₈H₆N₄)]·H₂O}_n, (I), and poly[[aqua‐μ₄‐pyridazino[4,5‐d]pyridazine‐μ₃‐sulfato‐disilver(I)] monohydrate], {[Ag₂(SO₄)(C₆H₄N₄)(H₂O)]·H₂O}_n, (II), possess three‐ and two‐dimensional polymeric structures, respectively, supported by N‐tetradentate coordination of the organic ligands [Ag—N = 2.208 (3)–2.384 (3) Å] and O‐pentadentate coordination of the sulfate anions [Ag—O = 2.284 (3)–2.700 (2) Å]. Compound (I) is the first structurally examined complex of the new ligand 4,4′‐bipyridazine; it is based upon unprecedented centrosymmetric silver–pyridazine tetramers with tetrahedral AgN₂O₂ and trigonal–bipyramidal AgN₂O₃ coordination of two independent Ag^I ions. Compound (II) adopts a typical dimeric silver–pyridazine motif incorporating two kinds of square‐pyramidal AgN₂O₃ Ag^I ions. The structure exhibits short anion–π interactions involving noncoordinated sulfate O atoms [O...π = 3.041 (3) Å].     

Crystallographic analysis of structures associated with a number of Tl- and Ag-containing sulfides: the composition–symmetry correlation

A crystallographic analysis is conducted of the structures of orthorhombic mineral sicherite TlAg₂(As,Sb)₃S₆, monoclinic synthetic sulfide Tl₃Ag₃Sb₂S₆, and triclinic mineral raberite Tl₅Ag₄As₆SbS₁₅. In the first two structures, the large and heavy Tl⁺ cation forms, together with the other cations, ordered “skeletal” frameworks with F and I cation sublattices that are close to cubic ones. In the structure of raberite, the Tl and Ag cations undergo, together with the sulfur anions, two-dimensional ordering by a zone of closely packed crystallographic planes, which generate a pseudohexagonal symmetry. The deviations from the 1 cation/anion stoichiometry are compensated: in the second structure, by a local consolidation of cations (to a distance Tl–Ag = 2.96 Å) and, in the third structure, through the formation of a dumbbell pair As–Ag (2.68 Å), which occupies one position in the sublattice.     

Transition-Metal-Induced Rearrangement of [(PhSn)4S6] Towards Ternary CuI/Sn/S or CuII/Sn/S Clusters

Direct access of ternary copper-tin sulfide clusters by reactions of a binary organotin sulfide cluster, [(PhSn)₄S₆] ( A ), with transition metal complexes was achieved for the first time without extra addition of further chalcogenide sources. This indicates that an in situ rearrangement of the inorganic core takes place even without initial formation of anionic fragments. The use of [Cu(PPh₃)₃Cl] or [Cu(PPh₃)₂Cl₂] as reactants yielded the ternary clusters [(CuPPh₃)₄(PhSn)₁₈Cu₆S₃₁Cl₂] ( 1 ) and [{Cu(PPh₃)₂}₂(PhSn)₃(SnCl)S₈] ( 2 ), respectively. Whereas 1 represents the largest neutral Cu/Sn/S cluster known to date, compound 2 , which is the first example of a ternary Cu/Sn/E (E=S, Se) cluster containing copper in the +II oxidation state, may be viewed as a very early stage of cluster formation. Apparently, the presence of Cu^II inhibits effective cluster growth, which rationalizes the lack of such species so far. The two ternary clusters exhibit very similar optical absorption energies despite their markedly different cluster sizes. According to time-dependent DFT calculations, this is due to different characters of the electronic excitation in the triplet compound 2 , as compared to the excitation of the closed shell cluster 1 , which serve to compensate for the different extensions of the clusters.     

Aqueous Sulfate Separation by Sequestration of [(SO4)2(H2O)4]4− Clusters within Highly Insoluble Imine‐Linked Bis‐Guanidinium Crystals

Selective crystallization of sulfate with a simple bis‐guanidinium ligand, self‐assembled in situ from terephthalaldehyde and aminoguanidinium chloride, was employed as an effective way to separate the highly hydrophilic sulfate anion from aqueous solutions. The resulting bis‐iminoguanidinium sulfate salt has exceptionally low aqueous solubility (K_sp=2.4×10^?10), comparable to that of BaSO₄. Single‐crystal X‐ray diffraction analysis showed the sulfate anions are sequestered as [(SO₄)₂(H₂O)₄]^4? clusters within the crystals. Variable‐temperature solubility measurements indicated the sulfate crystallization is slightly endothermic (ΔH_cryst=3.7 kJ mol^?1), thus entropy driven. The real‐world utility of this crystallization‐based approach for sulfate separation was demonstrated by removing up to 99 % of sulfate from seawater in a single step.     

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 .