Binuclear Silver (I) Complex with Double Armed Diaza-Crown Ether Containing Short Metal-Metal Separation

1992 ◽  
Vol 21 (4) ◽  
pp. 699-702 ◽  
Author(s):  
Ken Hirotsu ◽  
Ikuko Miyahara ◽  
Taiichi Higuchi ◽  
Mitsuo Toda ◽  
Hiroshi Tsukube ◽  
...  
Keyword(s):  
Crown Ether ◽  
Metal Separation ◽  
Metal Metal

Organic-inorganic hybrid materials from divalent metal cations and expanded N,N′-donor linkers

2018 ◽  
Vol 233 (2) ◽  
pp. 97-111 ◽  
Author(s):  
Mansoureh Zahedi ◽  
Behrouz Shaabani ◽  
Ulli Englert ◽  
Jan van Leusen
Keyword(s):  
Layer Structure ◽  
Metal Cations ◽  
Antiferromagnetic Coupling ◽  
Reaction Products ◽  
Ancillary Ligands ◽  
Orbital Interactions ◽  
Metal Separation ◽  
Metal Metal ◽  
Secondary Building Units ◽  
Simple Chain

AbstractThe rod-shaped linker (E,E)-N,N′-(3,3′-dimethyl-4,4′-biphenyldiyl)bis[1-(3-pyridinyl)methanimine] (L) is exploited for the first time in the synthesis of extended structures. Four new coordination polymers of composition {[ZnL(OAc)2]·EtOH}n(1), {[CdL(OAc)2]·MeOH}n(2), {[Cu2L(OAc)4]·CH2Cl2}n(3) and [MnL(N3)2]n(4) have been structurally characterized. The metal cations and the anionic ancillary ligands play pivotal roles for the topology of these compounds. In the crystalline reaction products of Zn(II), Cd(II) and Cu(II) acetate with the organic linker, the acetate anions connects two neighboring cations to dinuclear [M2(OAc)4] subunits. These secondary building units are further crosslinked by the N,N′-donor ligand, either perpendicular to the acetato bridges, leading to a ladder-like ribbon for1and2, or in the direction of the metal···metal separation, resulting in a simple chain in the case of3. Instead of dinuclear secondary building units, a different topology results from reaction of the N,N′ linker with Mn(ClO4)2in the presence of azide anions: 1,3 bridging by the N3−groups leads to infinite chains. These are crosslinked by L in perpendicular direction, and the layer structure4is obtained. Natural bond orbital (NBO) analyses revealed information on the basis of orbital interactions about the coordination environments of the metal ions. Thermogravimetric measurements indicate the highest thermal stability for2. Strong antiferromagnetic coupling within the dinuclear subunits of3is observed as a consequence of superexchangeviathe acetato bridges.

scholarly journals Crystal and solution structures of calcium complexes relevant to problematic waste disposal: calcium gluconate and calcium isosaccharinate

2018 ◽  
Vol 74 (6) ◽  
pp. 598-609 ◽  
Author(s):  
V. Bugris ◽  
Cs. Dudás ◽  
B. Kutus ◽  
V. Harmat ◽  
K. Csankó ◽  
...  
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
Solution Structures ◽  
Single Crystal Structures ◽  
Metal Separation ◽  
Metal Metal ◽  
Structure Determinations ◽  
Modelling Studies ◽  
Calcium Complexes ◽  
Intramolecular Hydrogen

The single-crystal structures of calcium D-gluconate and calcium α-D-isosaccharinate have been determined using X-ray diffraction at 100 K. Surprisingly, given its significance in industrial and medical applications, the structure of calcium D-gluconate has not previously been reported. Unexpectedly, the gluconate crystal structure comprises coordination polymers. Unusually, the calcium coordination number is nine. Adjacent metal centres are linked by three μ-oxo bridges, with a metal–metal separation of 3.7312 (2) Å. One of the gluconate ligands contradicts a suggestion from 1974 that a straight chain conformation is associated with an intramolecular hydrogen bond. This ligand binds to three adjacent metal centres. The use of synchrotron radiation provided an improved crystal structure with respect to that previously reported for the isosaccharinate complex, allowing the location of the hydroxy hydrogen sites to be elucidated. In contrast to the gluconate structure, there are no μ-oxo bridges in the isosaccharinate coordination polymer and the isosaccharinate bridging coordination is such that the distance between adjacent metal centres, each of which is eight-coordinate, is 6.7573 (4) Å. Complementing the crystal structure determinations, modelling studies of the geometries and coordination modes for the aqueous [CaGluc]+ and [CaIsa]+ complexes are presented and discussed.

scholarly journals Mono- and Binuclear Copper(II) and Nickel(II) Complexes with the 3,6-Bis(picolylamino)-1,2,4,5-Tetrazine Ligand

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2122
Author(s):  
Oleh Stetsiuk ◽  
Abdelkrim El-Ghayoury ◽  
Francesc Lloret ◽  
Miguel Julve ◽  
Narcis Avarvari
Keyword(s):  
Metal Ions ◽  
Zero Field ◽  
X Ray Diffraction ◽  
Zero Field Splitting ◽  
Metal Separation ◽  
Mononuclear Complexes ◽  
Distorted Octahedral ◽  
Metal Metal ◽  
Capping Ligands ◽  
New Compounds

Four new compounds of formulas [Cu(hfac)2(L)] (1), [Ni(hfac)2(L)] (2), [{Cu(hfac)2}2(µ-L)]·2CH3OH (3) and [{Ni(hfac)2}2(µ-L)]·2CH3CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by X-ray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN2O4 surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment. Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metal···metal separation are 7.97 (3) and 7.82 Å (4). Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of χMT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = −0.247(2) cm−1] and relatively weak intramolecular antiferromagnetic interactions [J = −4.86(2) cm−1] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = −JS1·S2). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties.

Quasiperiodic interfaces: HREM observations of grain and phase boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 332-333
Author(s):  
K. L. Merkle
Keyword(s):  
Atomic Structure ◽  
Direct Determination ◽  
Lattice Parameter ◽  
Atomic Scale ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Atomic Structures ◽  
Periodic Arrays ◽  
Parameter Ratio ◽  
Metal Metal

The atomic structures of internal interfaces have recently received considerable attention, not only because of their importance in determining many materials properties, but also because the atomic structure of many interfaces has become accessible to direct atomic-scale observation by modem HREM instruments. In this communication, several interface structures are examined by HREM in terms of their structural periodicities along the interface.It is well known that heterophase boundaries are generally formed by two low-index planes. Often, as is the case in many fcc metal/metal and metal/metal-oxide systems, low energy boundaries form in the cube-on-cube orientation on (111). Since the lattice parameter ratio between the two materials generally is not a rational number, such boundaries are incommensurate. Therefore, even though periodic arrays of misfit dislocations have been observed by TEM techniques for numerous heterophase systems, such interfaces are quasiperiodic on an atomic scale. Interfaces with misfit dislocations are semicoherent, where atomically well-matched regions alternate with regions of misfit. When the misfit is large, misfit localization is often difficult to detect, and direct determination of the atomic structure of the interface from HREM alone, may not be possible.

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