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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.
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