Controlled Expansion of a Strong‐Field Iron Nitride Cluster: Multi‐Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity

Multimetallic clusters have long been investigated as molecular surrogates for reactive sites on metal surfaces. In the case of the μ₄‐nitrido cluster [Fe₄(μ₄‐N)(CO)₁₂]^?, this analogy is limited owing to the electron‐withdrawing effect of carbonyl ligands on the iron nitride core. Described here is the synthesis and reactivity of [Fe₄(μ₄‐N)(CO)₈(CNAr^Mes2)₄]^?, an electron‐rich analogue of [Fe₄(μ₄‐N)(CO)₁₂]^?, where the interstitial nitride displays significant nucleophilicity. This characteristic enables rational expansion with main‐group and transition‐metal centers to yield unsaturated sites. The resulting clusters display surface‐like reactivity through coordination‐sphere‐dependent atom rearrangement and metal–metal cooperativity.     

Simultaneous Presence of Both Open Metal Sites and Free Functional Organic Sites in a Noncentrosymmetric Dynamic Metal–Organic Framework with Bimodal Catalytic and Sensing Activities

Assimilation of open metal sites (OMSs) and free functional organic sites (FOSs) with a framework strut has opened up a new route for the fabrication of novel metal–organic materials, thereby providing a unique opportunity to explore their multiple functionalities. A new metal–organic framework (MOF), {[Cu(ina)₂(H₂O)][Cu(ina)₂(bipy)]?2 H₂O}_n ( 1 ) (ina=isonicotinate, bipy=4,4′‐bipyridine), has been synthesized and characterized. Complex 1 is crystallized in the orthorhombic noncentrosymmetric space group Aba2 and consists of two different 2D coordination polymers, [Cu(ina)₂(H₂O)]_n and [Cu(ina)₂(bipy)]_n, with entrapped solvent water molecules. Hydrogen‐bonding interactions assemble these two different 2D coordination layers in a single‐crystal structure with interdigitation of pendant 4,4′‐bipy from one layer into the groove of another. Upon removal of guest molecules, 1 undergoes a structural transformation in single‐crystal‐to‐single‐crystal fashion with expansion of the effective void space. Each metal center is five‐coordinated and thus can potentially behave as an OMS, and the free pyridyl groups of pendant 4,4′‐bipy moieties and free ? C?O groups can act as free FOSs. Thus, owing to presence of both OMSs and free FOSs, the framework exhibits multifunctional properties. Owing to the presence of OMSs, the framework can act as a Lewis acid catalyst as well as a small‐molecule sensor material, and in a similar way, owing to the presence of free FOSs, it performs as a Lewis base catalyst and a cation sensor material. Furthermore, owing to noncentrosymmetry with large polarity along a particular direction, it shows strong second‐harmonic generation/nonlinear optical (SHG‐NLO) activity.     

Metal Complexes of Small Cycloalkynes and Arynes

Cyclooctyne is the smallest unsubstituted cycloalkyne that can be isolated in the free state and it is more reactive than acyclic alkynes towards transition metal complexes. Smaller cycloalkynes such as cycloheptyne, cyclohexyne, benzyne and cyclopentyne, which are transient molecules in the free state, can be stabilized by coordination either to mononuclear, electron-rich, transition metal-containing fragments, e.g. [ZrCp₂(PMe₃)] and M(PR₃)₂ (M = Ni, Pt), or by formation of dinuclear or polynuclear metal complexes, e.g. [Os₃H₂(CO)₉(C₆H₄)] and [Pt₂(μ-PPh₂)(μ-C₅H₆)(PPh₃)₃]. The alkynes can donate between two and four π-electrons to the metal centers, the higher number being favored for the early transition metals. The metal-cycloalkyne and metal-aryne bonds in the mononuclear complexes readily insert molecules containing C?O, C?C, C?C and C?N bonds, a feature that may be useful in organic synthesis. The highly unsaturated species 1, 4-benzdiyne acts as a bridging ligand between two metal centers in [{Ni(Cy₂PCH₂CH₂PCy₂)}₂(μ-C₆H₂)].     

Phosphomolybdate clusters as molecular building blocks in the design of one-, two- and three-dimensional organic-inorganic hybrid materials

An attractive approach to the design of inorganic solids exploits the tethering of inorganic clusters through organic spacers to produce hybrid materials with composite properties. We have recently described a modified strategy in which polyoxometalate clusters are linked through organic subunits to give an anionic hybrid substructure which may be further modified through the introduction of secondary metal-ligand complex (SMLC) cations, serving as a third component building block. In this application, the molybdophosphonate cluster {Mo₅O₁₅(O₃PR)₂}⁴⁻ serves as a secondary building unit (SBU) with alkyl (CH₂)_n or aromatic -(C₆H₄)_n- tethers providing one-dimensional structural expansion. A binucleating ligand such as tetrapyridylpyrazine (tpyprz) is used to bridge secondary metal sites into a binuclear {Cu₂(tpyprz)}⁴⁺ SBU which may link phosphomolybdate clusters into two- or three-dimensional structures. The influence of a variety of structural determinants is discussed, including the tether length of the diphosphonate ligand, the coordination preferences of the secondary metal, expansion of the ligand component of the SMLC, and substitution of As for P in the oxide SBU.     

On the Mechanism Behind the Instability of Isoreticular Metal–Organic Frameworks (IRMOFs) in Humid Environments

Increasing the resistance to humid environments is mandatory for the implementation of isoreticular metal–organic frameworks (IRMOFs) in industry. To date, the causes behind the sensitivity of [Zn₄(μ₄‐O)(μ‐bdc)₃]₈ (IRMOF‐1; bdc=1,4‐benzenedicarboxylate) to water remain still open. A multiscale scheme that combines Monte Carlo simulations, density functional theory and first‐principles Born–Oppenheimer molecular dynamics on IRMOF‐1 was employed to unravel the underlying atomistic mechanism responsible for lattice disruption. At very low water contents, H₂O molecules are isolated in the lattice but provoke a dynamic opening of the terephthalic acid, and the lattice collapse occurs at about 6 % water weight at room temperature. The ability of Zn to form fivefold coordination spheres and the increasing basicity of water when forming clusters are responsible for the displacement of the organic linker. The present results pave the way for synthetic challenges with new target linkers that might provide more robust IRMOF structures.     

Two new two‐dimensional coordination polymers based on isophthalate and a flexible N‐donor ligand containing benzimidazole and pyridine rings: synthesis,crystal structures and a solid‐state UV–Vis study

In coordination chemistry and crystal engineering, many factors influence the construction of coordination polymers and the final frameworks depend greatly on the organic ligands used. N‐Donor ligands with diverse coordination modes and conformations have been employed to assemble metal–organic frameworks. Carboxylic acid ligands can deprotonate completely or partially when bonding to metal ions and can also act as donors or acceptors of hydrogen bonds and are thus good candidates for the construction of supramolecular architectures. Two new transition metal complexes, namely poly[diaqua(μ₄‐1,4‐bis{[1‐(pyridin‐3‐ylmethyl)‐1H‐benz[d]imidazol‐2‐yl]methoxy}benzene)bis(μ₂‐isophthalato)dicobalt(II)], [Co(C₈H₄O₄)(C₃₄H₂₈N₆O₂)_0.5(H₂O)]_n, (1), and poly[diaqua(μ₄‐1,4‐bis{[1‐(pyridin‐3‐ylmethyl)‐1H‐benz[d]imidazol‐2‐yl]methoxy}benzene)bis(μ₂‐isophthalato)dicadmium(II)], [Cd(C₈H₄O₄)(C₃₄H₂₈N₆O₂)_0.5(H₂O)]_n, have been constructed using a symmetric N‐donor ligand and a carboxylate ligand under hydrothermal conditions. X‐ray crystallographic studies reveal that complexes (1) and (2) are isostructural, both of them exhibiting three‐dimensional supramolecular architectures built by hydrogen bonds in which the coordinated water molecules serve as donors, while the O atoms of the carboxylate groups act as acceptors. Furthermore, (1) and (2) have been characterized by elemental, IR spectroscopic, powder X‐ray diffraction (PXRD) and thermogravimetric analyses. The UV–Vis absorption spectrum of complex (1) has also been investigated.     

A ladder coordination polymer based on Ca2+ and (4,5‐dicyano‐1,2‐phenylene)bis(phosphonic acid): crystal structure and solution‐state NMR study

The preparation of coordination polymers (CPs) based on either transition metal centres or rare‐earth cations has grown considerably in recent decades. The different coordination chemistry of these metals allied to the use of a large variety of organic linkers has led to an amazing structural diversity. Most of these compounds are based on carboxylic acids or nitrogen‐containing ligands. More recently, a wide range of molecules containing phosphonic acid groups have been reported. For the particular case of Ca²⁺‐based CPs, some interesting functional materials have been reported. A novel one‐dimensional Ca²⁺‐based coordination polymer with a new organic linker, namely poly[[diaqua[μ₄‐(4,5‐dicyano‐1,2‐phenylene)bis(phosphonato)][μ₃‐(4,5‐dicyano‐1,2‐phenylene)bis(phosphonato)]dicalcium(II)] tetrahydrate], {[Ca₂(C₈H₄N₂O₆P₂)₂(H₂O)₂]·4H₂O}_n, has been prepared at ambient temperature. The crystal structure features one‐dimensional ladder‐like _∞¹[Ca₂(H₂cpp)₂(H₂O)₂] polymers [H₂cpp is (4,5‐dicyano‐1,2‐phenylene)bis(phosphonate)], which are created by two distinct coordination modes of the anionic H₂cpp²⁻ cyanophosphonate organic linkers: while one molecule is only bound to Ca²⁺ cations via the phosphonate groups, the other establishes an extra single connection via a cyano group. Ladders close pack with water molecules through an extensive network of strong and highly directional O—H…O and O—H…N hydrogen bonds; the observed donor–acceptor distances range from 2.499 (5) to 3.004 (6) Å and the interaction angles were found in the range 135–178°. One water molecule was found to be disordered over three distinct crystallographic positions. A detailed solution‐state NMR study of the organic linker is also provided.     

Two copper(II) metal–organic networks derived from bis-pyridyl-bis-amide ligands and aromatic polycarboxylates: a 2-D layered structure and a 4-connected trinodal 3-D topology

Two metal–organic coordination polymers, [Cu₃(4-bpcb)₂(1,2,4-btc)₂(H₂O)₂] (1) and [Cu₃(3-bpcb)₃(btec)_1.5] (2), have been synthesized from hydrothermal reaction of copper chloride with mixed ligands [4-bpcb?=?N,N′-bis(4-pyridinecarboxamide)-1,4-benzene, 3-bpcb?=?N,N′-bis(3-pyridinecarboxamide)-1,4-benzene, 1,2,4-H₃btc?=?1,2,4-benzenetricarboxylic acid, and H₄btec?=?1,2,4,5-benzenetetracarboxylic acid]. X-ray diffraction analysis reveals that 1 exhibits a 2-D layer structure and 2 possesses a three-dimensional (3-D) network. In 1 and 2, Cu^II ions are connected by bridging 1,2,4-btc or btec to form 2-D polymeric layers. Cu-1,2,4-btc layer does not propagate into a 3-D coordination framework in 1 due to 4-bpcb showing monodentate coordination (via ligation of only one pyridyl nitrogen). In 2, Cu-btec 2-D layers are further extended into a 3-D network with (6⁴.8²)₃ topology by 3-bpcb ligand in μ ₂-bridging coordination (via ligation of two pyridyl nitrogens). The different structures of the two complexes illustrate the influence of different polycarboxylates and N-donor positions of organic ligands on the formation of such coordination architectures. Moreover, the thermal properties and electrochemical properties of the copper complexes bulk-modified carbon paste electrodes have been studied.     

A Cationic MOF with High Uptake and Selectivity for CO2 due to Multiple CO2‐Philic Sites

The reaction of N‐rich pyrazinyl triazolyl carboxyl ligand 3‐(4‐carboxylbenzene)‐5‐(2‐pyrazinyl)‐1H‐1,2,4‐triazole (H₂cbptz) with MnCl₂ afforded 3D cationic metal–organic framework (MOF) [Mn₂(Hcbptz)₂(Cl)(H₂O)]Cl ? DMF ? 0.5 CH₃CN ( 1 ), which has an unusual (3,4)‐connected 3,4T1 topology and 1D channels composed of cavities. MOF 1 has a very polar framework that contains exposed metal sites, uncoordinated N atoms, narrow channels, and Cl^? basic sites, which lead to not only high CO₂ uptake, but also remarkably selective adsorption of CO₂ over N₂ and CH₄ at 298–333 K. The multiple CO₂‐philic sites were identified by grand canonical Monte Carlo simulations. Moreover, 1 shows excellent stability in natural air environment. These advantages make 1 a very promising candidate in post‐combustion CO₂ capture, natural‐gas upgrading, and landfill gas‐purification processes.     

A novel three‐dimensional SrII coordination polymer based on benzene‐1,2,4,5‐tetracarboxylate: hydrothermal synthesis,crystal structure and spectroscopic and thermal studies

Coordination of the anions of benzenecarboxylic acids with metal cations leads to coordination polymers with various structural features. Very few examples of strontium‐based structures have been reported. A new three‐dimensional coordination polymer, namely poly[aqua(μ₁₂‐benzene‐1,2,4,5‐tetracarboxylato)distrontium(II)], [Sr₂(C₁₀H₂O₈)(H₂O)]_n , has been synthesized under hydrothermal conditions and characterized by thermal analysis, vibrational spectroscopy (Raman and IR), single‐crystal X‐ray diffraction and powder X‐ray diffraction. The coordination geometries around the two independent Sr^II ions can be described as a distorted dodecahedron and a distorted monocapped square antiprism. The compound features a three‐dimensional structure containing inorganic motifs, with two‐dimensional layers connected through organic linkers, and possesses a topologic structure of a binodal (6,12) connected alb net with the Schläfli symbol {4¹⁵}₂{4⁴⁸.6¹⁸}. The final product of thermal decomposition is strontium oxide (SrO).     

Synthesis and Pyrolytical Solid-Phase Structural Transformations of New Oxorhenium(V) Complexes with 2-Benzoxazolethione

2-Benzoxazolethione reacts with the parent oxorhenium(V) complex, H₂[ReOCl₅], to yield either mononuclear or dinuclear complexes depending on the metal: ligand molar ratio and the concentration of hydrochloric acid containing the parent rhenium complex. The mononuclear complexs [ReOLCl(OH₂)₃]Cl₂, [ReOL₂(OH₂)₃]Cl₃ and [ReOLCl₃(OH₂)]; and dinuclear complexes [Re₂O₃(μ-L)₂Cl₄]·2H₂O and [Re₂O₂(μ-L)L₂Cl₆]-2H₂O were obtained. Both types of complexes have octahedral configurations. The mononuclear complexes prepared in 6N HCl or in 9N HCl undergo irreversible one-step solid-phase thermochromism transformation, thus, the colour of complexes changed from green to brown, black or bluish-green, upon heating. For the complexes obtained in 6N HCl, this step corresponds to structural changes due to the formation of other types of dinuclear complexes, while the mononuclear complex obtained in 9N HCl changes to another mononuclear complex with different coordination sites. On the other hand, the colour of the dinuclear complexes prepared in 2N HCl changed from brown to black, upon heating, in one step solid-phase thermochromism transformation corresponding to a change in the mode of coordination sites of the organic ligand. All thermal products obtained have octahedral configurations. The ligand behaves in these complexes either as a neutral, mono-, bidentate or monoanionic bidentate towards the oxorhenium ions. All complexes and the corresponding thermal products were isolated and their structures were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, ¹H NMR and TG-DTA measurements as well as by mass spectroscopy.     

Microscopic and Mesoscopic Dual Postsynthetic Modifications of Metal–Organic Frameworks

We report the dual postsynthetic modification (PSM) of a metal–organic framework (MOF) involving the microscopic conversion of C−H bonds into C−C bonds and the mesoscopic introduction of hierarchical porosity. MOF crystals underwent single-crystal-to-single-crystal transformations during the electrophilic aromatic substitution of Co₂(m-DOBDC) (m-DOBDC⁴⁻=4,6-dioxo-1,3-benzenedicarboxylate) with alkyl halides and formaldehyde. The steric hindrance caused by the proximity of the introduced functional groups to the coordination bonds reduced bond stability and facilitated the transformation into hierarchically porous mesostructures by etching with in situ generated protons (hydroniums) and halides. The numerous defect sites in the mesostructural MOFs are potential water-sorption sites. However, since the introduced functional groups are close to the main adsorption sites, even methyl groups are able to considerably decrease water adsorption, whereas hydroxy groups increase adsorption at low vapor pressures.     

Metal–Organic Coordination Strategy for Obtaining Metal-Decorated Mo-Based Complexes: Multi-dimensional Structural Evolution and High-Rate Lithium-Ion Battery Applications

Multi-dimensional metal oxides have attracted great attention in diverse applications due to their intriguing performances. However, their structural design remains challenging, particularly that based on organic chelation chemistry. Although metal–organic complexes with different architectures have been reported, their structure formation mechanisms are not well understood because of the complex chelation processes. Herein, we introduce a new metal–organic coordination strategy to construct metal-decorated (Ni, Co, Mn) Mo-based complexes ranging from 2D nanopetals to 3D microflowers. The chelating process of the metal–organic complex can be tuned by a surfactant, giving rise to different structures, and then a further metal can be appended. Thus, different metal (oxide)-decorated MoO₂/C-N structures were designed, enabling an extremely high lithium storage capability of 1018 mA h g⁻¹ and rate capacities of up to 10 A g⁻¹ over 1000 cycles. Relationships between electrochemical behavior and structure have been analyzed kinetically. A high-rate lithium-ion battery has been assembled from Ni-MoO₂/C-N and an Ni-rich layered oxide as the anode and cathode, respectively. We believe that this general metal–organic coordination strategy should be applicable to other multi-functional materials with superior capabilities.     

An Americium‐Containing Metal–Organic Framework: A Platform for Studying Transplutonium Elements

The synthesis, structure, and spectroscopic characterization of the first transplutonium metal–organic framework (MOF) is described. The preparation and structure of Am‐GWMOF‐6, [Am₂(C₆H₈O₄)₃(H₂O)₂][(C₁₀H₈N₂)], is analogous to that of the isostructural trivalent lanthanide‐only containing material GWMOF‐6. The presented MOF architecture is used as a platform to probe Am³⁺ coordination chemistry and guest‐enhanced luminescent emission, whereas the framework itself provides a means to monitor the effects of self‐irradiation upon crystallinity over time. Presented here is a discussion of these properties and the opportunities that MOFs provide in the structural and spectroscopic study of actinides.     

New Mechanistic Insight into Stepwise Metal‐Center Exchange in a Metal–Organic Framework Based on Asymmetric Zn4 Clusters

Herein, a mechanism of stepwise metal‐center exchange for a specific metal–organic framework, namely, [Zn₄(dcpp)₂(DMF)₃(H₂O)₂]_n (H₄dcpp=4,5‐bis(4′‐carboxylphenyl)phthalic acid), is disclosed for the first time. The coordination stabilities between the central metal atoms and the ligands as well as the coordination geometry are considered to be dominant factors in this stepwise exchange mechanism. A new magnetic analytical method and a theoretical model confirmed that the exchange mechanism is reasonable. When the metathesis reaction occurs between Cu^II ions and framework Zn^II ions, the magnetic exchange interaction of each pair of Cu^II centers gradually strengthens with increasing amount of framework Cu^II ions. By analyzing the changes of coupling constants in the Cu‐exchanged products, it was deduced that Zn4 and Zn3 are initially replaced, and then Zn1 and Zn2 are replaced later. The theoretical calculation further verified that Zn4 is replaced first, Zn3 next, then Zn1 and Zn2 last, and the coordination stability dominates the Cu/Zn exchange process. For the Ni/Zn and Co/Zn exchange processes, besides the coordination stability, the preferred coordination geometry was also considered in the stepwise‐exchange behavior. As Ni^II and Co^II ions especially favor octahedral coordination geometry in oxygen‐ligand fields, Ni^II ions and Co^II ions could only selectively exchange with the octahedral Zn^II ions, as was also confirmed by the experimental results. The stepwise metal‐exchange process occurs in a single crystal‐to‐single crystal fashion.     

A Soft Copper(II) Porous Coordination Polymer with Unprecedented Aqua Bridge and Selective Adsorption Properties

Herein, the synthesis, crystal structure, and full characterization of a new soft porous coordination polymer (PCP) of ([Cu₂(dmcapz)₂(OH₂)]DMF_1.5)_n ( 1 ) formulation, which is easily obtained in the reaction of CuX₂ (X=Cl, NO₃) salts with 3,5‐dimethyl‐4‐carboxypyrazole (H₂dmcapz) is present. Compound 1 shows a copper(II) dinuclear secondary building unit (SBU), which is supported by two pyrazolate bridges and an unprecedented H₂O bridge. The dinuclear SBUs are further bridged by the carboxylate ligands to build a diamondoid porous network. The structural transformations taking place in 1 framework upon guest removal/uptake has been studied in detail. Indeed, the removal of the bridging water molecules gives rise to a metastable evacuated phase ( 1 b ) that transforms into an extremely stable porous material ( 1 c ) after freezing at liquid‐nitrogen temperature. The soaking of 1 c into water allows the complete and instantaneous recover of the water‐exchanged material ( 1 a′ ). Remarkably, 1 b and 1 c materials possess structural bistability, which results in the switchable adsorptive functions. Therefore, the gas‐adsorption properties of both materials have been studied by means of single‐component gas adsorption isotherms as well as by variable‐temperature pulse‐gas chromatography. Both materials present permanent porosity and selective gas‐adsorption properties towards a variety of gases and vapors of environmental and industrial interest. Moreover, the flexible nature of the coordination network and the presence of highly active convergent open metal sites confer on these materials intriguing gas‐adsorption properties with guest‐triggered framework‐breathing phenomena being observed. The plasticity of Cu^II metal center and its ability to form stable complexes with different coordination numbers is at the origin of the structural transformations and the selective‐adsorption properties of the studied materials.     

Heterometallatom-Koordinationsverbindungen Re2(μ-PPh2)2[mer-(CO)3]2-trans-[InX2(H2O)]2 und neue halogenhaltige drei- und vierkernige Rheniumcluster aus Reaktionen zwischen Re2[μ-PPh2)2(CO)8] und InX3 (X = Cl,Br, I)

Heterometallic Coordination Compounds Re₂(μ-PPh₂)₂[mer-(CO)₃]₂-trans-[InX₂(H₂O)]₂ and New Halogene Containing Three- and Four-Nuclear Rhenium Clusters from Reactions between Re₂(μ-PPh₂)₂(CO)₈ and InX₃ (X = Cl, Br, I) In sealed glass tubes equimolar amounts of Re₂(μ-PPh₂)₂(CO)₈ and InX₃ (X = Cl, Br, I) were reacted in the presence of xylene at 220°C to two types of products. The first type comprised the heterometallic coordination compounds Re₂(μ-PPh₂)₂(CO)₆[InX₂(H₂O)]₂ (X = Cl, Br, I) (yield 60%), and the second halogene containing rhenium complexes Re₃(μ₃-H)(μ₃-X)(μ-PPh₂)₃(CO)₆ (unsaturated three-membered metal ring with 46 VE) and Re₄(μ-H)(μ-X)(μ-PPh₂)₄(μ₄-PPh)(CO)₈ and additionally those substances as cis-IRe(CO)₄(PPh₂H), Re₂(μ-PPh₂)(μ-X)(CO)₈ (X = Cl, Br), Re₂(μ-I)₂[μ-(PPh₂)₂O](CO)₆ and Re₄(μ-Cl)₂(μ-PPh₂)₄(μ₄-PPh)(CO)₈ (four-membered metal ring with 66 VE with three Re? Re bonds) which have been observed in one or two of the three reaction systems. A proposal of the reaction course is discussed. The single X-ray analysis of Re₂(μ-PPh₂)₂[mer(CO)₃]₂-trans[InI₂(H₂O)]₂ · 2 Me₂CO shows for the two fold phosphido bridged dirhenium molecular fragment with 34 VE a Re? Re bond of 294.6(1) pm. From two possible transpositions of both In? Re bond vectors, the one found advantageously has sterical reasons. The average In? Re single bond length is 271.1(1) pm. The corresponding determination of the unsaturated three-membered ring compound Re₃(μ₃-H) (μ₃-Cl)(μ-PPh₂)₃(CO)₆ showed three Re? Re bond lenghts of comparable size, of which the mean value of 281.9(1) pm was significantly shortened by π electron delocalization effect compared to that of a saturated phosphido bridged three-membered rhenium ring compound. As it was recognized by further comparison, the structural data of the common molecular fragments in the three examined three-membered rhenium ring clusters (X = Cl, Br, I) are not dependent on the different kind of halogeno ligand atoms. Finally, the crystal structure determination of the substance Re₄(μ-H)(μ-Br)(μ-PPh₂)₄(μ₄-PPh)(CO)₈ shows the presence of square-pyramidal Re₄(μ₄-P) atomic arrangement, of which the planar basic plane has a sequence of up- and downwards orientated four diphenylphosphido bridging groups. The four measured Re? Re single bond lengths (mean value 302.7(3) pm change with the different kind of bridging atoms. The structural features observed are compared with those of a corresponding iodine derivative.     

A Dirhoda-Heterocyclic Carbene

The linear μ-carbido complex [Rh₂(μ-C)Cl₂(dppm)₂] (dppm=bis(diphenylphosphino)methane) reacts with dimethylacetylene dicarboxylate (DMAD) to afford [Rh₂(μ-C)(μ-DMAD)Cl₂(dppm)₂], which features a bent RhCRh linkage (124.7°) that might be described as a dirhoda-heterocyclic carbene, as demonstrated by coordination to further metal centers.     

Structural characterization of dinuclear Ti(IV) complexes of rigid tetradentate dianionic diamine bis(phenolato) ligands; effect of steric bulk on coordination features

A small difference in diamine bis(phenolato) ligands, namely an additional single methylene unit, directs formation of dinuclear Ti(IV) complexes rather than mononuclear ones as characterized by X-ray crystallography. Varying steric bulk of the ligand affects the coordination number in the dinuclear complexes and the ligand to metal ratio. A ligand with reduced steric bulk leads to a L₂Ti₂(OiPr)₄ type complex featuring two octahedral metal centers bridged only by the two phenolato ligands, whereas a bulky ligand leads to a Ti₂(μ-L¹)(μ-OiPr)₂(OiPr)₄ type complex with a single chelating ligand, two bridging isopropoxo ligands, and two terminal isopropoxo groups on each of the two metal centers, which are of trigonal bi-pyramidal geometry.     

Two Series of Sandwich Frameworks Based on Two Different Kinds of Nanosized Lanthanide(III) and Copper(I) Wheel Cluster Units

Two series of sandwich frameworks, [La₆(μ₃‐OH)₂(ox)₃L₁₂Cu₁₁(μ₃‐X)₆(μ₂‐X)₃]?8 H₂O (X=Br/Cl, FJ‐21 a/b ; L=4‐pyridin‐4‐yl‐benzonate; ox=oxalate) and [Ln₄(OAc)₃(H₂O)₄L₉][Cu(μ₃‐I)]@[Cu₁₀(μ₃‐I)(μ₄‐I)₆(μ₅‐I)₃]?7H₂O (Ln=Pr/Nd/ Sm/Eu, FJ‐22 a / b / c / d ; OAc=acetate) have been hydrothermally prepared. These sandwich frameworks are assembled by two different kinds of nanosized lanthanide(III) and copper(I) wheel cluster units, La₁₈ and 3Cu@Cu₂₄ in FJ‐21 , Ln₂₄ and Cu₂@Cu₂₄ in FJ‐22 . The synergistic coordination between organic ligands, L and oxalate/acetate, leads to the formation of La₁₈ and Ln₂₄ wheels, while the synergistic coordination between organic L and inorganic Br/I ligands results in 3Cu@Cu₂₄ and Cu₂@Cu₂₄ wheels for FJ‐21 and FJ‐22 , respectively. Thus, two types of synergistic coordination between two different organic ligands, as well as inorganic and organic ligands are simultaneously observed in FJ‐21 and FJ‐22 .