Oxotris(oxalate)niobate(v): an oxalate delivery agent in the design of building blocks
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Universidade Federal de Minas Gerais
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Artigo de periódico
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This work concerns the oxalate delivery process that occurs when using (NH4)3[NbO(C2O4)3]·6H2O as a suitable oxalate source in the synthesis of two compounds, [Cu(dmphen)(C2O4)(H2O)] (1) and [{Cu(dmphen)(CH3OH)}2(μ-C2O4)](ClO4)2 (2) (dmphen = 2,9-dimethyl-1,10-phenanthroline). {[Fe{HB(pz)3}(CN)2(μ-CN)]2[{Cu(dmphen)}2(μ-C2O4)]}∙xCH3OH (3) (2.0 ≤ x ≤ 2.4) was obtained by reacting 2 and PPh4[Fe{HB(pz)3}(CN)3]∙H2O [ PPh+4 = tetraphenylphosphonium and HB(pz)-3 = tris(pyrazolyl)borate]. Crystal structures of 1–3 have been determined by single-crystal X-ray diffraction experiments: 1 is a mononuclear trigonal bipyramidal copper(II) species, 2 is a centrosymmetric oxalato-bridged dicopper(II) complex, and 3 consists of centrosymmetric tetranuclear FeIII2CuII2 units with intramolecular iron–copper and copper–copper distances around 5.010(1) and 5.1833(9) Å, respectively. Variable-temperature magnetic measurements of 2 and 3 were carried out from 50 to 350 (1) and 1.9 to 300 K (3). A strong antiferromagnetic interaction between copper(II) ions occurs in 2 (J = −340 cm−¹, the spin Hamiltonian being defined as H=-JScu1·Scu1i). Analysis of the magnetic data of 3 shows magnetic interactions across the oxalate (J1 = −341 cm−¹) and single cyanide (J2 = +12.9 cm−¹) … (J2 = +12.9 cm−¹) bridges. Simple symmetry considerations of the interacting magnetic orbitals in 2 and 3 provide a clear picture of the exchange pathways involved in these complexes.
Abstract
Assunto
Compostos metálicos, Propriedades magnéticas, Cristalografia de raio X, Cobre, Ferro, Nióbio, Química inorgânica
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Copper(ii), Iron(iii), Niobium(V), Oxalate, Cyanide, Heterobimetallic compounds, Magnetic properties
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https://www.tandfonline.com/doi/full/10.1080/00958972.2018.1428313