Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

The X-ray crystal structures, magnetic susceptibilities from 2 to 300 K, and theoretical analyses of the magnetism for 1D and trinuclear azido Cu^II carboxylate complexes [Cu_1.5(hnta)(N₃)₂(H₂O)]_n (1) and [Cu₃(hnta)₄(N₃)₂(H₂O)₃] (2), respectively, where hnta is 6-hydroxynicotinate, are described. Although both exhibit strong ferromagnetic coupling, discrete complex 2 exhibits long-range ferromagnetic ordering, while the very similar 1D system 1 does not. Density functional calculations provided accurate J values and allowed rationalization of the ferromagnetic coupling in terms of the magnetic orbitals and spin densities.

The formation of two novel phenoxo-bridged linear trimetallic Cu^II and Ni^II complexes, [Cu₃(μ-L)₂](CH₃OH)₂(ClO₄)₂ (1) and [Ni₃(μ-L)₂(CH₃OH)₂](ClO₄)₂ (2), with a new diazamesocyclic ligand functionalised by additional phenol donor pendants (H₂L = N,N′- bis(2-hydroxybenzyl)-1,4-diazacycloheptane), has been achieved and both complexes have been characterised by IR spectroscopy, elemental analyses, conductivity measurements, thermal analyses and UV/Vis techniques. Single-crystal X-ray diffraction analyses revealed that both 1 and 2 have the similar phenoxo-bridged linear trinuclear cores. For 1, two terminal and the central Cu^II ion are in square-planar environments with the adjacent intramolecular Cu···Cu separation of 2.9376(9) Å. For 2, however, two terminal Ni^II ions are in square-planar environments and the central Ni^II ion assumes an octahedral geometry by axial coordination of two methanol ligands, the adjacent intramolecular Ni···Ni distance being 3.007(3) Å. In both cases, the 1,4-diazacycloheptane (DACH) ring adopts the normal boat configuration. The magnetic properties of complexes 1 and 2 have been investigated by variable-temperature magnetic susceptibility measurements in the solid state. Complex 1 displays a very strong antiferromagnetic coupling interaction between the neighbouring μ-phenoxo Cu^II centres with a J parameter of −314 cm⁻¹ and the magneto-structural correlation for such complexes is discussed in detail. For complex 2, the result indicates that both terminal Ni^II ions are diamagnetic and the central Ni^II shows typical paramagnetic behaviour. The presence of zero-field splitting for Ni^II with a D parameter of 11 cm⁻¹, being active at low temperature, is further corroborated by the magnetisation measurement at 2 K. Additionally, the interesting ESR spectra of 1 at different temperatures (from 298 K to 8 K) were investigated and interpreted. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Four new disulfoxide-Ln^III complexes, [Ln(L)₂(NO₃)₃]_n {Ln = La (1), n = n; Ln = Gd (2), Dy (3) and Yb (4), n = 2}, have been prepared by the reaction of Ln(NO₃)₃·nH₂O with meso-1,3-bis(ethylsulfinyl)propane (meso-L) in methanol/triethylorthoformate, and their solid-state structures were characterized by IR spectroscopy, elemental analyses and X-ray diffraction. Complex 1 is a 1D double-bridged chain in which the La^III ions are ten-coordinate and the L ligands adopt both meso and rac configurations, and a bis-monodentate bridging coordination mode. While complexes 2–4 have isostructural dinuclear structures, in which the Ln^III ions are nine-coordinate and the ligands show two types of coordination fashions and configurations: bis-monodentate bridging with a meso-configuration, and monodentate coordination with a rac-configuration. The structural differences between 1 and 2–4 indicate the influence of lanthanide contraction on the complex structures. In addition, a change in configuration of the ligand occurs when it reacts with metal ions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The preparation, crystal structure and magnetic properties of the first tetrameric Co^II cluster with a unique planar triangular motif, [Co₄L₃(H₂O)₂](ClO₄)₂·2H₂O (1), based on a carboxylic-functionalized 1,5-diazacyclooctane (DACO) bridging ligand [1,5-bis(2-carboxyethyl)-DACO], are reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A new trisulfoxide ligand, 1,3,5-tris(ethylsulfinyl)-2,4,6-trimethylbenzene (L), was designed and synthesized, and treated with Ln(NO₃)₃ or Ln(ClO₄)₃ to produce three coordination polymers: [Ln(L)(MeOH)(NO₃)₃]_n [where Ln = La^III (1); Nd^III (2)] and {[La(L)(DMF)₅](ClO₄)₃}_n (3). Solid-state structures of all three complexes were determined by single-crystal X-ray diffraction. The three complexes have 1D helical-chain structures and complexes 1 and 2 are isostructural. To the best of our knowledge, these coordination polymers are the first examples of (trisulfoxide)metal complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The construction of two unique, high-nuclearity Cu^II supramolecular aggregates with tetrahedral or octahedral cage units, {(μ₃-Cl)[Li⊂ Cu₄(μ-L¹)₃]₃}(ClO₄)₈(H₂O)_4.5 (1) and {[Na₂⊂Cu₁₂(μ-L²)₈(μ-Cl)₄](ClO₄)₈(H₂O)₁₀(H₃O⁺)₂}_∞ (2) by alkali-metal-templated (Li⁺ or Na⁺) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N′-bis(3-propionyloxy)-1,4-diazacycloheptane (H₂L¹) or 1,5-diazacyclooctane-N,N′-diacetate acid (H₂L²). Complex 1 crystallizes in the trigonal R̄3c space group (a = b = 20.866(3), c = 126.26(4) Å and Z = 12), and 2 in the triclinic P space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) Å, α = 99.836(6), β = 95.793(5), γ = 116.124(5)° and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu₄ tetrahedral cage units with a Li⁺ template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu₆ polyhedra with a Na⁺ template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.

Being bulky is good: The use of a bulky multifunctional ligand is key to the successful construction of a neutral 3D copper coordination polymer that shows 1D open channels and the first interpenetrating NbO-type network (see picture). The absorption properties of the complex are investigated.

Einem sterisch anspruchsvollen Brückenligand fällt die Schlüsselrolle bei der Konstruktion eines neutralen dreidimensionalen Kupfer-Koordinationspolymers zu. Diese Verbindung ist der erste Festkörper mit verzahnten Netzen vom NbO-Typ. Wegen seiner offenen Kanäle (siehe Bild) wurden die Absorptionseigenschaften des Koordinationspolymers untersucht.

Two novel diazamesocyclic ligands based on l,5-diazacyclooctane (DACO) and functionalized with additional pyridyl donor groups, namely 1,5-bis(2-pyridylmethyl)-1,5-diazacyclooctane (L¹) and 1-(2-pyridylmethyl)-1,5-diazacyclooctane (L²), have been synthesized and characterized, as have their Cu^II complexes. Crystal structure analyses revealed that with Cu(ClO₄)₂L¹ forms a five-coordinate mononuclear complex [Cu^IIL¹Cl]ClO₄ (1), whereas L² forms a µ-Cl⁻-bridged dinuclear complex [Cu^II(L²)Cl]₂(ClO₄)₂ (2). Furthermore, it has been found that the apical chloride anion of 1 may be easily exchanged by azide anion, forming the mononuclear complex [Cu^IIL¹(N₃)]ClO₄ (3). There is a notable difference between 3 and 1 in that 3 forms a quasi-two-dimensional network through intermolecular C−H···O hydrogen bonds and π−π stacking interactions. Each Cu^II center in the three complexes is pentacoordinated in a distorted square-pyramidal environment and the DACO ring of each ligand adopts a boat-chair configuration in all the complexes. In the mononuclear complexes 1 and 3, the Cl⁻ or N₃⁻ anions occupy the apical sites, whereas in the dinuclear complex 2 the two bridging Cl⁻ anions occupy both axial positions as well as one equatorial position, leading to an intramolecular Cu···Cu separation of 3.396 Å. Variable-temperature magnetic susceptibility measurements on 2 in the range 4−300 K indicate a weak intramolecular ferromagnetic coupling between adjacent Cu^II centers with 2J = 2.28 cm⁻¹; the magneto-structural correlations are discussed in detail. The solution behavior of the complexes has been further studied by UV/vis and ESR techniques.

A penta-coordinated Ni(II) complex with a 1,5-diazacyclooctane (DACO) ligand functionalized by two imidazole donor pendants, [NiL¹Cl] (ClO₄) H₂O (1) (where L¹ = 1,5-bis (imidazol-4-ylmethyl)-l,5-diazacyclooctane) has been synthesized and characterized by X-ray diffraction, infrared spectra, elemental analyses, conductance, thermal analyses and UV-Vis techniques. Complex 1 crystallizes in triclinic crystal system, P-l space group with a = 0.74782(7), b = 1.15082 (10), c = 1.23781(11) nm, α = 82.090(2), β = 73.011(2), γ = 83.462(2)°, V = 1.00603(16) nm³, M, = 486.00, Z = 2, D_c = 1.604 g/cm³, final R = 0.0435, and wR = 0.1244. The structures of 1 and its related complexes show that in all the three mononuclear complexes, each Ni(II) center is penta-coordinated with a near regular square pyramid (RSP) to distorted square-pyramidal (DSP) coordination environment due to the boat/chair configuration of DACO ring in these complexes, and the degree of distortion increases with the augment of the size of the heterocyclic pendants. In addition, the most striking feature of complex 1 resides in the formation of a two-dimensional network structure through hydrogen bonds and stabilized by π-π stacking. The solution behaviors of the Ni(II) complexes are also discussed in detail.

Fillings and cavities: Three novel pseudo-octahedral metal–organic frameworks, 1–3, consisting of macrometallacyclic noninterpenetrating meso networks and exhibiting weak antiferromagnetic interactions, have been constructed from Cu^II centers and structurally flexible R,S-bis(sulfinyl) ligands. Varying the chain length of ligands is found to control the cavity sizes of the networks.

Füllungen und Hohlräume: Die drei neuartigen metallorganischen Pseudooktaedergerüste 1–3 wurden aus Cu^II-Zentren und R,S-Bis(sulfinyl)-Liganden verschiedener Größe aufgebaut. Die Gerüste bestehen aus metallacyclischen Netzwerken ohne Durchdringung und zeigen schwache antiferromagnetische Wechselwirkungen. Die Größe der Hohlräume innerhalb des Netzwerkes lässt sich durch Variation der Kettenlänge des Liganden steuern.