The synthesis, characterization, structure and magnetic properties of a hexametallic mixed-metal iron(III)-cobalt(III) compound are described. The compound has been characterized by standard... Show moreThe synthesis, characterization, structure and magnetic properties of a hexametallic mixed-metal iron(III)-cobalt(III) compound are described. The compound has been characterized by standard spectroscopic and analytical methods to determine its composition. Single-crystal X-ray diffraction has shown that the asymmetric unit consists of discrete dinuclear dicationic units of {(mu-oxido-mu-[sulfato-O1,O2])bis[tris(2-pyridyl-methyl)amineiron(III)]}(2+), herein designated as Fe12, and two half-dinuclear dianionic units of {(mu-oxido)bis[(mu-cyanido-kappa N-pentacyanidocobaltato(III))(tris(2-pyridyl-methyl)-amine)iron(III)]}(2-) units, herein designated as Fe33a and Fe44b, generating the overall composition Co2Fe4O2(C-N)(12)(tpa)(4), 1, where tpa is tris(2-pyridyl-methyl)amine. X-ray structural results and thermogravimetric and differential scanning calorimetry measurements also indicate that the compound, depending upon its history, may contain up to nine interstitial waters of hydration, herein designated as 1(H2O)(9).In the dinuclear dicationic unit, the bridging Fe-O-Fe bond in Fe12 is bent and there is also an FeOSOFe sulfato-based bridge with an angle of 132.8 degrees. In contrast, in the two dinuclear dianionic units, Fe33a and Fe44b, the Fe-O-Fe bond angle is crystallographically constrained to be 180 degrees. The Co-C-N-Fe bonds are almost co-linear, with Co-C-N angles of 176 degrees and C-N-Fe angles of 169 degrees. In each species the tpa ligand is tripodal tetradentate with the tertiary amine trans to the sulfato ligand or to the cyanide ligand in the dianions or the bridged oxido ligand in the dications. Bond lengths and angles are all in the typical range for Fe(III) and Co(III) compounds.The magnetic behavior of 1(H2O)(9), obtained upon cooling from 300 to 2 K, reveals a strong antiferromagnetic interaction between the Fe(III) ions in each dinuclear unit. Attempts to discriminate between the two Fe(III) dinuclear units in 1(H2O)(9) have in all cases led to two very different Heisenberg isotropic exchange coupling constants, namely J = -220(2) and -716(32) cm(-1) for 1(H2O)(9); i.e. one of the dinuclear units, probably the Fe12 unit, is so strongly antiferromagnetically coupled that it is close to diamagnetic between 2 and ca. 250 K and has a Heisenberg S = 0 ground state. (C) 2018 Elsevier Ltd. All rights reserved. Show less
Setifi, Z.; Ghazzali, M.; Glidewell, C.; Perez, O.; Setifi, F.; Gomez-Garcia, C.J.; Reedijk, J. 2016
The synthesis, characterization, single crystal structure and magnetic properties of the compound [(CuN3(OH2))(2)(adp)](n) (1) are presented, in which adp stands for the adipate(2-) anion. This... Show moreThe synthesis, characterization, single crystal structure and magnetic properties of the compound [(CuN3(OH2))(2)(adp)](n) (1) are presented, in which adp stands for the adipate(2-) anion. This compound consists of layers containing chains of six-coordinated Cu(II) ions; the chains are connected by mu(4)-adipate anions. The magnetically interesting part of the compound is the Cu(II) chain, built from 3 bridging ligands, i.e. a water ligand, an azide anionic ligand bridging by using a terminal N atom to connect 2 Cu(II) ions, and one symmetrically bridging carboxylato group of adipate; the other end of the tetradentate adipate anions symmetrically connect the chains, forming the layers.From the magnetic point of view the compound is considered as a Cu(II) chain with a quite unusual, symmetrical water bridge, the mu-syn-syn carboxylate and the mu-N-3 bridge. The bridging water also hydrogen bonds to a terminal N of a nearby azido ligand. Magnetic susceptibility measurements show that 1 presents moderate ferromagnetic intrachain interactions (J(chain), = +38.4 cm(-1)) with a metamagnetic behaviour for the inter-chain interaction with a critical field of 0.7 T. (C) 2016 Elsevier Ltd. All rights reserved. Show less
![The synthesis, characterization, X-ray structure and magnetism of dinuclear-based bis[mu-(1,1,3,3-tetracyano-2-ethoxypropenido-kappa N-2,N) (1,1,3,3-tetracyano-2-ethoxypropenido-kappa N)(2,2-bipyridine)copper(II)] organized in alternating chains via semi-](/sites/all/modules/custom/islandora_solr_search/images/defaultimg.png?solr_nav%5Bid%5D=e6ce9082a06d20982b10&solr_nav%5Bpage%5D=0&solr_nav%5Boffset%5D=2)
