Type

Database

Creator

Date

Thumbnail

Search results

18 records were found.

In the title compound, [Co2(C2H3O2)4(C7H6N2)4(H2O)], the half-molecule in the asymmetric unit is completed by a crystallographic twofold rotation axis to give the full molecule. The CoII ions are approximately octahedrally coordinated with a cis-N2O4 coordination sphere. The compound features intramolecular O-HO hydrogen bonds between the non-bridging acetate groups and the bridging water molecule, and intermolecular N-HO hydrogen bonds between the acetates and amine H atoms of the benzimidazoles which determine the molecular packing in the crystal structure.
A rational design based on the proton-coupled electron transfer (PCET) concept allows us to structurally characterize for the first time isolable, air- and moisture-stable semiquinone radicals in a zwitterionic neutral form. The presence of an alkoxy and the bulky pyridinio substituents causes only a minor perturbation of either the redox potentials or the spectral UV-vis characteristics of the semiquinone core but significantly stabilizes the new radicals.
Three novel isomorphous transition metal phosphonate compounds with formula [M(OOCC6H4PO3H)(H2O)] [M(II) = Mn(1), Co(2), Ni(3)] were prepared through hydrothermal reaction of 2-carboxyphenylphosphonic acid and metal salts. Within the structure, the {M2O2} dimers made up of edge-sharing{MO6} octahedra are connected by carboxylate and/orphosphonate groups, leading to a 2-D layer. The phenyl groups fill in the inter-layer spaces. Magnetic measurements reveal that dominant antiferromagnetic interactions are observed in compounds 1 and 2, while for compound 3, the dominant ferromagnetic interaction leads to a spontaneous ferromagnetic long range ordering below T-c = 4.0 K.
The synthesis, crystal structures and magnetic properties of five new manganese compounds are reported. These include a linear trinuclear cluster [Mn(II)(3)(O(2)CCHMe(2))(6)(dpa)(2)]center dot 2MeCN (1) (dpa = 2,2'-dipyridylamine), a tetranuclear cluster [Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(bpy)(2)] (3) (bpy = 2,2'-bipyridine), and chain coordination polymers composed of cluster blocks such as Mn(3), Mn(3)O, and Mn(4)O(2) bridged by 2,2'-bipyrimidine (bpm) or hexamethylentetramine (hmta) ligands to give ([Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(bpm)]center dot 2EtOH)(n) (2), [Mn(II)(2)Mn(III)(2)O(2)(O(2)CCHMe(2))(6)(bpm)(EtOH)(4)](n) (4), and (([Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(hmta)(2)]center dot EtOH)(n) (5). The magnetic analysis of the compounds was achieved using a combination of vector coupling and full-matrix diagonal...
We present a series of eight layered copper(II) malonates, each with a {[HA](2)[Cu(II)(mal)(2)(H(2)O)]}(n) A-B-A layer structure, where A is an ammonium cation and 13 is an anionic copper malonate layer (x = 1 or 2; A = benzylamine, 1; S-(alpha)-methylbenzylamine, 2; 4-methylbenzylamine, 3; 4-carboxybenzylamine, 4; 4-trifluoromethylbenzylamine, 5; 4-trifluoromethoxybenzylamine, 6; phenylethylamine, 7; and 4-fluorophenylethylamine, 8). The ammonium cations used are primary amines based around benzylamine and phenylethylamine and include several different functional groups. The different amines give a large array of interlayer interactions, including van der Wail Is packing, hydrogen bonding, C-H center dot center dot center dot pi, pi-center dot center dot center dot pi, H center dot center dot center dot F, and F center dot center dot ...
The reaction between Cu(NO(3))(2)center dot 3H(2)O, 2,2':6',2 ''-terpyridine(tpy) and 3,6-di(pyrid-2-yl) pyridazine (1) in a 2 : 2 : 1 molar equivalent ratio in aqueous MeCN in the presence of excess NH(4)PF(6) leads to competition between the assembly of the dinuclear half-grid [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 2H(2)O and the mononuclear complex [Cu(1)(2)(OH(2))][PF(6)](2). The yield of [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 2H(2)O has been optimized using microwave conditions. [Cu(1)2(OH(2))][PF(6)](2) can be selectively produced by treating Cu(NO(3))(2)center dot 3H(2)O with 1 (1:2 molar equivalents) in aqueous MeCN in the presence of NH(4)PF(6). The single crystal structures of [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 4MeNO(2) and [Cu(1)(2)(OH(2))][PF(6)](2) are presented. In the [Cu(2)(1)(tpy)(2)](4+) cation, ligand 1 bridges t...
Novel cationic mixed-ligand palladium and platinum complexes based on the chelating ligands 4,7-dimethyl-1, 10-phenanthroline and 2,2'-bipyridine with a pyridine bearing the nitronylnitroxide radical are reported. The synthesis, X-ray crystal structures and magnetic properties of the two complexes [Pd(4,7-dimethyl-1,10-phenanthroline)(NIT-pPY)(2)](PF6)(2). DMF and [Pt(2,2'-bipyridine-NN')(NIT-pPY)(2)](PF6)(2) center dot 0.25H(2)O, (where NIT-pPy = 2-(p-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) are described. The two metal complexes show a strained square planar geometry. Short intermolecular contacts take place through the nitroxide groups and weak intermolecular antiferromagnetic interactions are dominant at low temperature. (c) 2007 Elsevier B.V. All rights reserved.
A π-extended, redox-active tetradentate tetrathiafulvalene-fused salphen [salphen = N,N′-phenylenebis(salicylideneimine)] compound (L) was prepared via a direct Schiff-base condensation of the corresponding diamine-tetrathiafulvalene (TTF) precursor with salicylaldehyde. Its chelating coordination ability has been demonstrated by the formation of the corresponding transition metal complexes in the presence of M(OAc)2·nH2O (M = Co(II), Ni(II), Cu(II)) and FeCl3·6H2O. Three complexes have been characterized by single-crystal X-ray diffraction analysis showing that the TTF-salphen ligand coordinates to the metal ions in a planar mode through the nitrogen and oxygen atoms in a N2O2 cis-configuration. In the case of Fe(III), a dinuclear oxo-bridged Fe(III) complex is formed. These paramagnetic complexes are promising building blocks for the...
Redox-active dithiolated tetrathiafulvalene derivatives (TTFdT) were inserted in two-dimensional nanoparticle arrays to build interlinked networks of molecular junctions. Upon oxidation of the TTFdT to the dication state, we observed a conductance increase of the networks by up to 1 order of magnitude. Successive oxidation and reduction cycles demonstrated a clear switching behavior of the molecular junction conductance. These results show the potential of interlinked nanoparticle arrays as chemical sensors.
Want to know more?If you want to know more about this cutting edge product, or schedule a demonstration on your own organisation, please feel free to contact us or read the available documentation at http://www.keep.pt/produtos/retrievo/?lang=en