Heptanuclear Cluster Research Articles

Preparation, catalytical activity and crystal structure of a heptanuclear zinc acetate cluster

Reaction of [Zn4(µ4-O)(O2CCH3)6] with one equivalent of 4-tertiary-butylpyridine leads to a nearly quantitative formation of the heptanuclear cluster [Zn7O2(O2CCH3)10(tbupy)2] (1). Here, we present the crystal structure of 1 and first results of the examination of its catalytic activity in transesterification reactions and polymerization of lactide compared to the activity of [Zn4(µ4-O)(O2CCH3)6] in the presence of 4-tertiary-butylpyridine.

Syntheses, Crystal Structure and Property of a Heterometallic Heptanuclear Cluster

A novel heterometallic heptanuclear cluster [(hmbame)2 $$Co_{4}^{III}$$ CoIINa2(N3)8 (OH)2]·4H2O (1), (H3hmbame is 6,6′-((1Z,1′E)-(((3-ethoxy-2-hydroxyphenyl) methylene)bis(azanylylidene))bis(methanylylidene))bis (2-ethoxy phenol)) was synthesized by in situ reaction. Complex 1 was structurally characterized by elemental analysis, IR, UV–Vis spectroscopy and single crystal X-ray diffraction. Complex 1 crystallizes in the triclinic space group Pī, showing a disc-like configuration. Luminescent property of 1 has been studied. The results indicate that it may be good candidate for useful photoactive material.

A Disc-Like Heptanuclear Nickel Cluster Based on Schiff Base: Synthesis, Structure, Magnetic Properties and Hirshfeld Surface Analysis

A new disc-like heptanuclear cluster [Ni7(immep)6(MeO)6]·(NO3)2 (1, Himmep is 2-imminomethyl-6-ethxoy-phenol) was synthesized through microwave assisted reaction of Ni(NO3)2·6H2O with 2-hydroxy-3-ethoxy-benzaldehyde and ammonium water in mixed solvent (acetonitrile:methanol = 1:1). 1 was characterized by IR spectroscopy, elemental analysis and X-ray single-crystal diffraction. Magnetic property of 1 was discussed. The core of 1 displays dominant ferromagnetic interactions from the nature of the binding modes through μ 3-OCH3. According to the 3D Hirshfeld surface and 2D fingerprint plots, the main interactions in 1 are the H···H, O···H, and C···H contacts.

Studies on the Magnetic Ground State of a Spin Möbius Strip.

Here we report the synthesis, structure and detailed characterisation of three n-membered oxovanadium rings, Nan [(V=O)n Nan (H2 O)n (α, β, or γ-CD)2 ]⋅m H2 O (n=6, 7, or 8), prepared by the reactions of (V=O)SO4 ⋅x H2 O with α, β, or γ-cyclodextrins (CDs) and NaOH in water. Their alternating heterometallic vanadium/sodium cyclic core structures were sandwiched between two CD moieties such that O-Na-O groups separated the neighbouring vanadyl ions. Antiferromagnetic interactions between the S=1/2 vanadyl ions led to S=0 ground states for the even-membered rings, but to two quasi-degenerate S=1/2 states for the spin-frustrated heptanuclear cluster.

Five Disk‐Shaped {MII7} (M = Mn, Fe, Co, Cu, Zn) Clusters and One Capsule‐Like {CuII6NaI2} Cluster Assembled from the Same Schiff Base Ligand

Six transition‐metal clusters of compositions [Mn7L6](NO3)2·2CH3OH (1), [Fe7L6](NO3)2·2CH3OH (2), [Co7L6](NO3)2·2CH3OH (3), [Cu7L6](NO3)2 (4), [Zn7L6](NO3)2·2CH3OH (5), and [Cu6Na2L6](NO3)2·4CH3OH (6) {H2L = 2‐(2‐hydroxy‐3‐methoxybenzylideneamino)phenol} have been synthesized under solvothermal conditions. The structures of 1–6 have been established based on single‐crystal X‐ray diffraction studies. Complexes 1–5 possess disk‐shaped {MII7} cores, with the central MII ion and the six peripheral MII ions being linked by six µ3‐O atoms. The six MII ions of the rim of the disk are bridged in a pairwise manner by six µ2‐O atoms. Complex 2 is a very rare example of a disk‐shaped {Fe7} cluster in which all of the Fe atoms exhibit +2 oxidation state. Furthermore, this is the first time that the five isostructural heptanuclear clusters were constructed by using an identical Schiff base ligand. The molecule of complex 6 contains a capsule‐like {Cu6Na2} core. In this core, two sodium ions reside on the two vertices of the capsule and the 12 vertices of the {Cu6O6} hexagonal prism are occupied by alternately arrayed six CuII ions and six O atoms. Photoluminescence studies suggest strong emission for 5 in the solid state at room temperature. Variable‐temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4 and 6. The ac susceptibility studies were also performed with 3. Strong out‐of‐phase, χ′′, signals were observed for 3 at zero field, suggesting that 3 is a class of single molecule magnet (SMM).

Sequential Synthesis of 3d-3d'-4f Heterometallic Heptanuclear Clusters in between Lacunary Polyoxometalates.

In this work, we have successfully created several unprecedented discrete 3d-3d'-4f heterotrimetallic clusters in between lacunary polyoxometalates (POMs). By the three-step sequential introduction of metal cations into a trivacant lacunary POM TBA4H6[A-α-SiW9O34] (TBA = tetra-n-butylammonium) in organic media, five kinds of sandwich-type POMs with double-diamond-shaped 3d-3d'-4f heptanuclear clusters (IIIFeM4Ln2, TBAnHm[FeM4{Ln(L)2}2O2(A-α-SiW9O34)2], M = Mn(3+), Cu(2+); Ln = Gd(3+), Dy(3+), Lu(3+); L = acac (acetylacetonate), hfac (hexafluoroacetylacetonate)) were successfully synthesized for the first time. By introduction of two [Ln(L)2](+) units on the ends of pentanuclear clusters [FeMn4O18(OH)2](23-) and [FeCu4O18(OH)2](27-), the magnetic interactions between Mn(3+)-Mn(3+) and Cu(2+)-Cu(2+) could be modulated. Among a series of the heterometallic heptanuclear compounds, IIIFeMn4Lu2 exhibited the slow magnetic relaxation characteristic for a single-molecule magnet under the zero applied magnetic fields.

Synthesis and Characterization of Two Isostructural Lanthanide‐Containing Metal‐Organic Frameworks Constructed from an Unprecedented [Ln7(μ3‐OH)8]13+ Cluster

AbstractTwo isostructural metal‐organic frameworks formulated as [Gd7(L)4(μ3‐OH)8(HCOO)(DMF)6(H2O)]·DMF·H2O (1) and [Tb7(L)4(μ3‐OH)8(HCOO)(DMF)5(H2O)]·DMF·H2O (2) (H3L=3,5‐di(4′‐carboxylphenyl)benzoic acid) have been synthesized and structurally characterized. The building blocks of the structures are the heptanuclear lanthanide clusters of the dicubane‐like type [Ln7(μ3‐OH)8]13+ (Ln=Gd, Tb) which are formally assembled into porous three‐dimensional networks through the linkage of L. Variable temperature magnetic studies down to 2 K reveal antiferromagnetic interactions in complex 1. Furthermore, the fluorescence property of 2 was also studied.

Mercury- and cadmium-assisted [2 + 2] cyclodimerization of tert-butylselenium diimide.

The complexes [MCl2{N,N'-(t)BuNSe(μ-N(t)Bu)2SeN(t)Bu}] [M = Cd (1), Hg (2)] were obtained in high yields by the reaction of tert-butylselenium diimide Se(IV)(N(t)Bu)2 with CdCl2 or HgCl2 in tetrahydrofuran. Recrystallization of 1 and 2 from acetonitrile (MeCN) afforded yellow crystals of 1·MeCN and 2·MeCN, respectively. Isomorphic 1·MeCN and 2·MeCN contain an unprecedented dimeric selenium diimide ligand, which is N,N'-chelated to the metal through exocyclic imido groups. In addition to the complexes 1 and 2, the (77)Se NMR spectra of acetonitrile solutions of 1·MeCN and 2·MeCN indicated the presence of the dimeric (t)BuNSe(μ-N(t)Bu)2SeN(t)Bu, monomeric Se(IV)(N(t)Bu)2, and cyclic selenium imides. Density functional theory calculations at the PBE0/def2-TZVPP level of theory were used to assign the (77)Se resonances of the dimer. A comparison of Gibbs energies of formation of some metal dichloride complexes [MCl2{N,N'-Se(IV)(N(t)Bu)2}] and [MCl2{N,N'-(t)BuNSe(μ-N(t)Bu)2SeN(t)Bu}] (M = Zn, Cd, Hg) indicated that the formation of complexes containing a dimeric selenium diimide ligand is favored over those containing a monomeric ligand for the group 12 metals. In the case of the group 10 metal halogenides (M = Ni, Pd, Pt), the Gibbs energies of the complexes with monomeric Se(IV)(N(t)Bu)2 ligands are close to those containing dimeric (t)BuNSe(μ-N(t)Bu)2SeN(t)Bu ligands. A plausible reaction pathway with a low activation energy involves the initial formation of [MCl2{N,N'-Se(IV)(N(t)Bu)2}] (M = Zn, Cd, Hg), which then reacts with another molecule of Se(N(t)Bu)2, leading to the final [MCl2{N,N'-(t)BuNSe(μ-N(t)Bu)2SeN(t)Bu}] complex. Without the presence of group 12 metal halogenides, the [2 + 2] cyclodimerization of Se(IV)(N(t)Bu)2 is virtually thermoneutral, but the activation energy is relatively high, which accounts for the kinetic stability of (t)BuNSe(μ-N(t)Bu)2SeN(t)Bu in solution. A minor byproduct, [Cd7Cl14{N,N'-Se(II)(NH(t)Bu)2}6]·4CH2Cl2, was identified by X-ray crystallography as a heptanuclear cluster with selenium(II) diamide ligands N,N'-chelated to the cadmium centers.

Microwave Assisted Synthesis, and Structure of a Co-Crystal Nickel Complex with 2-ethoxy-6-methyliminomethyl-phenol

A new co-crystal complex [Ni7(emmp)6(OH)6][Ni(emmp)2]·(CH3CN)2·(ClO4)2 (1, Hemmp is 2-ethoxy-6-methyliminom-ethyl-phenol) has been synthesized by microwave-assist solvothermal method. Complex 1 was characterized by IR spectroscopy, elemental analysis, and X-ray single-crystal diffraction. The 1 was consist of a nano-bowl-like heptanuclear cation cluster [Ni7(emmp)6(OH)6]2+, two counterion ClO4−, one neutral mononuclear complex [Ni(emmp)2] and two acetonitrile molecules. The five part of 1 constructed a whole through M···H interaction, O–H···N hydrogen bonds and C–H···O hydrogen bonds.

Microwave-assisted synthesis, structure and properties of a co-crystal compound with 2-ethoxy-6-methyliminomethyl-phenol

A new co-crystal complex [Ni7(emmp)6(CH3O)2(OH)4][Ni(emmp)2]·(ClO4)2 (1, Hemmp is 2-ethoxy-6-methyliminomethyl-phenol) has been synthesised by microwave-assisted method. Complex 1 was characterised by IR spectroscopy, elemental analysis, Raman spectroscopy and X-ray single-crystal diffraction. The complex consists of a heptanuclear cation cluster [Ni7(emmp)6(CH3O)2(OH)4]2+, a mononuclear complex [Ni(emmp)2] and two counteranions. Complex 1 displays the contents of antiferromagnetic and ferromagnetic properties.

Introduction to the themed issue on Advanced Complex Inorganic Nanomaterials

Energy, environmental issues and health care are amongst the top priorities of modern society. Such strategic issues have sparked phenomenal interest in inorganic nanomaterials as they hold great promise to develop new advanced devices and equipment which could revolutionise the way we live. Investigating the structuration of materials on the nanoscale has revealed unprecedented physical (optics, magnetism, etc.) and chemical (e.g. catalysis) properties that are absent in bulk matter of the same chemical composition. These specific functionalities are the consequence of a complex multi-level organisation (chemical, structural, textural) of the architecture of inorganic nanomaterials. The global properties and functional performances largely depend on the extent to which these levels are mastered during the synthesis process. A new forum to discuss the evolution and extraordinary revolution brought by such nanomaterials wasmost welcome. This was the scope of the second International Conference on Advanced Complex Inorganic Nanomaterials (ACIN) held in Namur (Belgium), July 15–19, 2013, which was jointly organised by the Laboratory of Inorganic Materials Chemistry at the University of Namur and the Institute of Condensed Matter and Nanosciences (IMCN) at the University Catholique de Louvain. This meeting gathered an impressive set of renowned international speakers (Michael Graetzel, Zhong Lin Wang, Susumu Kitagawa, Mathias Driess, Xinhe Baho, Marie-Paule Pileni, Leone Spiccia, Lee Cronin, Min Gu, Paolo Samori, Mir Wais Hosseini, Shin-ichi Ohkoshi and Di Zhang, to name but a few) including Nobel Prize winner Jean Marie Lehn, who presented original results. To celebrate this international inorganic chemistry event, New Journal of Chemistry (CNRS and RSC Publishing) present a themed issue gathering original contributions presented as 4 NJC Letters, 25 full papers, 4 Focus reviews and 6 Perspective reviews. This forum offers an update of recent innovations in both fundamental and applied aspects of inorganic nanomaterials (inorganics, ceramics, complexes, hybrids and bio-inspired materials). The latest advances and progress on advanced preparation methods are discussed. In particular, hydrothermal routes are largely used to produce Bi2WO6 microspheres (Zhou et al.), BaTiO3 tube-like arrays (Lamberti et al.), as well as NH4V3O8microcrystals or V2O5 (Vernardou et al.) and H2V3O8 nanowire bundles (Han, Mai et al.) to improve electrochemical performances. Microwave assisted methods are employed to prepare EuPO4 H2O nanostructures (Tran Thu et al.) and layered simple hydroxides (Rogez et al.). Template assisted methods are followed to synthesise ZnO nanostructures/nanowires (Stassi, Cauda et al.) or porous BN and Si/B/C/N monoliths (Miele et al.). We can also point out an original self-assembly route combined with a ship-in-a-bottle method for mesoporous catalysts (Sun et al.), and a surface modification method to functionalize a graphite electrode (Toda, Hayami et al.). Finally, ion exchange methods to produce hollow micro/ nanostructures materials are reviewed by Yan and Rosei. The active field of coordination polymers (CPs)/MOFs and hybrids is also covered. In their review, Van der Voort et al. provide a useful survey of vanadium MOFs and their applications in adsorption, separation and catalysis, whereas Janiak, Henninger et al. highlight novel industrial applications of MOFs for heat transformation. Oshio et al. disclose the crystal structure of an achiral CP whereas Chen et al. present a flexible CP based on a rare heptanuclear Zn cluster featuring selective adsorption properties of alkylbenzene isomers, which are widely used in the chemical industry. Potential Mg precursors to MOFs are also presented (Wilson et al.). Non-siliceous hybrid organic– inorganic nanostructures are reviewed by Yuan et al. whereas Tremel et al. present a Institute of Condensed Matter and Nanosciences, Molecules, Solids, Reactivity (IMCN/MOST), Universite Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve, Belgium. E-mail: yann.garcia@uclouvain.be b Laboratory of Inorganic Materials Chemistry, University of Namur, 61 rue de Bruxelles, 5000, Namur, Belgium. E-mail: bao-lian.su@unamur.be c Clare Hall College and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom. E-mail: bls26@cam.ac.uk DOI: 10.1039/c4nj90013h

New 2D zinc phosphonates with heptanuclear units, reversible dehydration–hydration and bright luminescence

Two new zinc phosphonates with formulas [Zn18(L)12(H2N(CH2)4NH2)2]·25.5H2O (1) and [Zn9(L)6(HN(C2H4NH2)2)2]·10H2O (2) have been synthesized starting from zinc acetate, 1-C10H7-CH2N(CH2COOH)(CH2PO3H2) (H3L) and 1,4-butanediamine (for 1)/diethylenetriamine (for 2). Compounds 1 and 2 are characterized by single-crystal X-ray crystallography, powder XRD, elemental analysis, IR spectroscopy, and thermogravimetric (TG) analysis. In the crystal structures of compounds 1 and 2, Zn7 heptanuclear clusters are bridged by [Zn2(H2N(CH2)4NH2)] and [Zn(HN(C2H4NH2)2)] fragments, respectively, to form two-dimensional (2D) frameworks. Compound 1 is a dynamic framework upon the dehydration–hydration process and displays bright purple emission, while the framework of compound 2 is stable up to 250 °C under an air atmosphere. And the luminescence of compound 2 can be tuned by heating treatment.

New strategy to construct single-ion magnets: a unique Dy@Zn6 cluster exhibiting slow magnetic relaxation

Two unique heptanuclear clusters Ln@Zn6 (Ln = Dy (1), Er (2)) were structurally and magnetically characterized. Each Dy(3+)/Er(3+) is located in a nona-coordinate D(3h) coordination environment, and is encapsulated in a diamagnetic Zn6 cage. Compound 1 exhibits single-ion magnetic behavior, and is the first example of a single-ion magnet (SIM) constructed through embedding one magnetic anisotropic metal ion into a diamagnetic cage.

Synthesis, structure, and photoluminescence of a (4,6)-connected Cu(I)–CN–triazolate framework built with a unique heptanuclear hybrid cluster

A 3-D Cu(I)–CN–triazolate hybrid coordination polymer, {Cu9(NH2-BPT)2(BPT)2(CN)7}n (1) (NH2-BPT = 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole, BPT = 3,5-bis(3-pyridyl)-1,2,4-triazole), has been synthesized via self-assembly of NH2-BPT, CuCN, and K3Fe(CN)6 under hydrothermal conditions. Single-crystal X-ray diffraction data show that four of the five independent copper centers in 1 have a three-coordinated trigonal coordination geometry, and the remaining copper center has a two-coordinated linear geometry. Three Cu ions are linked by one cisoid-BPT and two CN− to form a 16-membered ring subunit, which is joined by the two-coordinate copper center via the triazole N(4)-position to generate an unprecedented [Cu7(BPT)2(CN)4] hybrid heptanuclear cluster. Each heptanuclear motif is linked to two adjacent [Cu7] clusters through four CN− anions, and further to four [Cu–CN–Cu] binuclear clusters through two transoid-NH2-BPT ligands. Each of these [Cu–CN–Cu] units is linked to four neighboring heptanuclear motifs. The overall geometry is a 3-D (4,6)-connected topological framework with Schläfli symbol of (44 × 62)(44 × 610 × 8). Compound 1 also exhibits high thermal stability and strong green fluorescence emission at 536 nm in the solid state.

Four Coordination Polymers Based on Identical Eight-Connected Heptanuclear Clusters: Spin Canting, Spin Glass, Antiferromagnetism, and Gas Adsorption

Four 3D coordination polymers, [Co7(OH)4(H2O)2(ina)4(ip)3]·10H2O (1·10H2O, ina = isonicotinate, ip = isophthalate), [Ni7(OH)4(H2O)2(ina)4(ip)3]·10H2O (2·10H2O), [Co7(OH)4(H2O)2(ina)4(pip)3]·5H2O (3·5H2O, pip = 5-phenyl-isophthalate), and [Ni7(OH)4(H2O)2(ina)4(pip)3]·5H2O (4·5H2O), respectively, were hydrothermally synthesized. They crystallized in the orthorhombic space group Pba2 for 1·10H2O and 2·10H2O and monoclinic space group P2/n for 3·5H2O and 4·5H2O, respectively, and were constructed with the identical 8-connected heptanuclear {M7(OH)4} (M = Co(II) or Ni(II)) clusters, possessing uninodal hexagonal primitive net with the point symbol {3(6)·4(18)·5(3)·6}. The four coordination polymers showed dominant antiferromangetic properties, in which 1·10H2O shows spin-canted behavior and 2·10H2O exhibits the coexistence of spin canting and spin glass. Meanwhile, the activated polymers 1 and 2 possessed permanent porosity, displaying relatively large H2 uptake capacity (77 K, 1 atm) of 114 and 133 cm(3) g(-1), and CO2 uptake capacity (273 K, 1 atm) of 65.8 and 73.3 cm(3) g(-1), for 1 and 2, respectively.

Two disc-like heptanuclear clusters based on Schiff base: syntheses, structure and magnetic properties

Two new disc-like heptanuclear complexes [Ni7(mmimp)6(MeO)6]·2(ClO4) (1), [Ni7(mmimp)6(MeO)6]·2(NO3) (2) were synthesised, where Hmmimp is 2-methoxy-6-methyliminomethyl-phenol. The two compounds were characterised by elemental analysis, IR and X-ray single-crystal diffraction. Compounds 1 and 2 are heptanuclear clusters with the similar cubane topology in which the metal ions and the oxygen, nitrogen atoms from the mmimp− ligands possess a planar hexagonal disc-like structure. Magnetic properties of 1 and 2 have been discussed. The {Ni7} (1) and {Ni7} (2) cores display dominant ferromagnetic interactions from the nature of the binding modes through μ3-OCH3− .

Complex Gadolinium-Oxo Clusters Formed along Concave Protein Surfaces

Protein-bound contrast: The unusual observation of a heptanuclear gadolinium-oxo cluster on the surface of the cell-adhesion protein Flo5A establishes the basis for directed incorporation of poly-lanthanide clusters into biomolecules. The observed gadolinium cluster might serve as a paradigm for the design of protein-based MRI contrast agents.

New compounds based on polyoxometalates and metal halide clusters

Seven new compounds based on polyoxometalates and metal halide clusters have been synthesized and characterized by IR, XPS, UV-vis, XRD, elemental analyses and single crystal X-ray diffraction analyses. Compounds 1, 2, 3 and 4 are hybrids based on polyoxometalates and ennea-nuclear metal halide clusters, which are isomorphous to the compounds we reported recently. Compounds 5–7 are new examples of hybrids based on polyoxometalates and metal halide clusters, of which compounds 5 and 6 are the first examples of hybrids based on polyoxometalates and a new kind of hepta-nuclear metal halide cluster and compound 7 is the first example of hybrid based on polyoxometalates and octakaideca-nuclear metal halide clusters. In addition, compounds 2, 3 and 4 are the first examples of hybrids based on polyoxometalates and metal bromide clusters, and compounds 5 and 6 are the second examples of hybrids based on polyoxometalates and metal iodine clusters. Furthermore, compound 7 is the first example of compounds based on POMs and metal halide extended structures.

Polynuclear heterometallic cadmium(II)/silver(I) phenylthiolates: Syntheses and structures of [Cd3(μ-SPh)6(μ3-SPh)4Ag4(PPh3)4] and [Cd3(OMe)2(μ-SPh)4(μ3-SPh)8Ag8(μ-dppp)4] (dppp = 1,3-bis(disphenylphosphino)propane)

Abstract Reaction of [Me4N]2[Cd(SPh)4] and [Ag(PPh3)2NO3] (molar ratio = 1:1) in MeOH/CH2Cl2 (1:1) followed by recrystallization from DMF/Et2O yielded a neutral heptanuclear cluster, [Cd3(μ-SPh)6(μ3-SPh)4Ag4(PPh3)4] (1), while interaction of [Me4N]2[Cd(SPh)4] with AgNO3 and dppp (molar ratio = 4:6:3) gave a neutral undecanuclear cluster [Cd3(OMe)2(μ-SPh)4(μ3-SPh)8Ag8(μ-dppp)4] (2). Crystal structures and photoluminescent properties of the two clusters in solid state were reported.

Positional disorder of Cu(ii) ions in a cluster: a novel heptanuclear Cu(ii) core supported by 4-bromo-3,5-dimethylpyrazolate

Two copper(II)-cluster complexes with intriguing heptanuclear cores have been synthesized and characterized by crystallographic and magnetic methods. Due to the positional disorder of copper(II) ions, the actual heptanuclear cluster demonstrates an asymmetric feature distinct from the previous reports.