Search results for "bond"

Synthesis, Structure, and Magnetic Properties of the Oxalate-Based Bimetallic Ferromagnetic Chain {[K(18-crown-6)][Mn(H2O)2Cr(ox)3]}∞ (18-crown-6 = C…

2005

The salt [K(18-crown-6)][Mn(H2O)2Cr(ox)3]·0.5(18-crown-6) (1) has been prepared and structurally and magnetically characterized. It crystallizes in the P21/c space group [a = 21.011(2) A, b = 11.265(2) A, c = 15.748(3) A, β = 105.952(6)°, V = 3584(1) A3, and Z = 4] and contains [Mn(H2O)2Cr(ox)3]∞ chains connected through hydrogen bonding to form 2D anionic networks. The magnetic exchange is ferromagnetic [J = +2.23(2) cm-1] in the chain and also in between chains, reaching bulk ferromagnetic ordering below 3.5 K.

Crystal structure, magnetic properties and esr studies of (4-apyH)4[CuIIBr4] [CuIBr2]2: a novel Cu(II)⧹Cu(I) system containing bromocuprate(I) chains…

1998

Abstract The synthesis, crystal structure, ESR spectra and magnetic properties are reported for the Cu(II)⧹Cu(I) compound (4-apyH)4[Cu3Br8] (4-apyH = C5H7N2 = 4-aminopyridinium). Single-crystals of the compound were grown by slow diffusion of n-hexane on an ethanolic solution of (4-apyH)2[CuBr4] · H2O. The crystal structure is made up of organic cations, isolated [CuIIBr4]2− anions and infinite [CuIBr2]nn− chains composed of edge-sharing CuIBr4 tetrahedra. N–H · · · Br hydrogen bond interactions between organic counter cations and inorganic anionic units are present and contribute to the cohesiveness of the crystal packing. Magnetic susceptibility measurements showed a good isolation of Cu(…

The interaction of deoxyribonucleic acid with methyltin(IV) moieties in solution studied by small-angle X-ray scattering, circular dichroism and UV s…

2000

The nature of calf thymus DNA in aqueous solution, in the presence of the organotin(IV) species Sn IV Me 3 , Sn IV Me 2 and Sn IV Me, possibly partly hydrolysed and/or hydrated, was investigated by small-angle X-ray scattering (SAXS), ultraviolet spectroscopy (UV) at different temperatures and circular dichroism (CD). The results are compared with those of previous 119 Sn Mossbauer studies on condensed DNA phases. The effects of tin-phosphate oxygen bonding on the DNA melting profile in DNA-Sn IV Me systems are in agreement with previous reports on DNA-Main Group metal ion interactions. The structure and conformation of the DNA double helix are not influenced by Sn IV Me n species, even in …

Weak interactions between trivalent pnictogen centers: computational analysis of bonding in dimers X3E...EX3 (E = pnictogen, X = halogen).

2009

The nature of weak interactions in dimers X(3)E...EX(3) (E = N-Bi, X = F-I) was investigated by wave function and density functional theory (DFT)-based methods. Out of the 20 systems studied, 10 are found to be bound at the CP-MP2 and LMP2 levels of theory. Detailed partition of the interaction energy into different components revealed that dispersion is the primary force holding the dimers together but there also exists an important ionic component whose contribution increases with increasing halogen size. As expected, standard density functionals fail to describe bonding in the studied systems. However, the performance of DFT methods can be easily improved via empirical dispersion correct…

Synthesis, electrochemistry, and spectroelectrochemistry of (P)Ge(Fc)2 and (P)Ge(C6H5)(Fc): first example of metal-carbon-.sigma.-bonded porphyrins w…

1988

Dithiametacyclophane mit Dreifachbindungen

1994

Dithiametacyclophanes with Triple Bonds Schemes 1 and 2 show the syntheses of dithia[8]metacyclo-phanes 4a-d and tetrathia[m.n]metacyclophanes 9, 10 by cyclization reactions applying the cesium effect. All these cyclophanes contain C—C triple bonds which influence the molecular dynamics; especially the halogen substituents in 4b-d obstruct the topomerization.

Synthese von 9‐Oxabicyclo[6.1.0]non‐3‐in

1987

Ausgehend von 1,5-Cyclooctadien (1) wird in einer siebenstufigen Synthese die Titelverbindung 9 gewonnen. Sie liegt in zwei Konformationen 9a und 9b vor, wobei in 9a eine starke sterische Wechselwirkung zwischen dem Sauerstoffatom und der gespannten Dreifachbindung auftritt. Zur Einfuhrung der Dreifachbindung dient die thermische Fragmentierung des 1,2,3-Selenadiazols 7. Der Strukturnachweis fur die regiospezifische Bildung von 7 wird mit 2D-NMR-Spektroskopie gefuhrt. Starting with 1,5-cyclooctadiene (1), the title compound 9 is gained in a synthesis of seven steps. 9 exists in two conformations 9a and 9b, of which 9a shows a strong interaction between the oxygen atom and the strained tripl…

Synthesis and Crystal Structure of a Novel Lamellar Barium Derivative:  Ba(VOPO4)2·4H2O. Synthetic Pathways for Layered Oxovanadium Phosphate Hydrate…

1997

A unified synthetic strategy has allowed us to rationalize the preparative chemistry of the layered oxovanadium phosphates M(VOPO4)2·nH2O. Thus, we have been able to isolate as single phases with reasonable yields both all the previously characterized phosphates and a new solid containing Ba2+ cations as guest species as well as to prepare new related derivatives involving arsenate anions. In order to organize the experimental results, we have used two complementary models:  a simple restatement of the partial charge model (PCM), and the valence matching principle (VMP) (derived from the bond valence method). The crystal structure of the new barium lamellar derivative, Ba(VOPO4)2·4H2O, has …

Lattice dynamics of the ionic superconductor Li4C60. Inelastic neutron scattering and powder averaged lattice dynamics (PALD) investigations

2016

1‐Oxa‐3‐cyclooctin

1990

1-Oxa-3-cyclooctyne According to an MNDO calculation, 1-oxa-cyclooctyne (13) and 1-oxa-3-cyclooctyne (14) are 8-membered heterocyclic ring systems with high steric energy (ring strain). On the basis of THF (1) and acetoacetic ester (4), a multi-step synthesis is described for 14. The triple bond is introduced in the last step by a thermal fragmentation of the 1,2,3-selenadiazole 12.