Aza and cyanobridged tripodal dinuclear copper(II) complexes: Electrochemical studies and structural evidence for an original azacyanocarbanion

Gomila, Antoine; Douziech, Bénédicte; Cosquer, Nathalie; Poul, Nicolas Le; Michaud, François; Gómez‐García, Carlos J.; Mest, Yves Le; Conan, Françoise

doi:10.1016/j.ica.2013.11.024

Cited by 2 publications

(1 citation statement)

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“…Even though several dinuclear copper(II) compounds with doubly bridged N 3 – have been reported, the number of compounds with a single end-on (μ-1,1) N 3 – exclusively mediating the superexchange interaction is limited, and in these examples the Cu–N–Cu bridging angle is relatively low, ∼90–115°. The CN – bridged dinuclear compounds are even less extensively studied as a result of the reducing character of this anion in the presence of copper(II) . We also describe the structure of the pentametallic copper(I) I – bridged compound that was isolated in an attempt to synthesize the copper(II) dinuclear metallacycle with the large I – ion as the bridging group; the reducing effect of iodide on copper(II) is well-known, and only a few successful attempts are documented where species with a copper(II)-iodide bond were isolated …”

Section: Introductionmentioning

confidence: 99%

Syntheses, Structural, Magnetic, and Electron Paramagnetic Resonance Studies of Monobridged Cyanide and Azide Dinuclear Copper(II) Complexes: Antiferromagnetic Superexchange Interactions

et al. 2015

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The reactions of Cu(ClO4)2 with NaCN and the ditopic ligands m-bis[bis(1-pyrazolyl)methyl]benzene (Lm) or m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*) yield [Cu2(μ-CN)(μ-Lm)2](ClO4)3 (1) and [Cu2(μ-CN)(μ-Lm*)2](ClO4)3 (3). In both, the cyanide ligand is linearly bridged (μ-1,2) leading to a separation of the two copper(II) ions of ca. 5 Å. The geometry around copper(II) in these complexes is distorted trigonal bipyramidal with the cyanide group in an equatorial position. The reaction of [Cu2(μ-F)(μ-Lm)2](ClO4)3 and (CH3)3SiN3 yields [Cu2(μ-N3)(μ-Lm)2](ClO4)3 (2), where the azide adopts end-on (μ-1,1) coordination with a Cu-N-Cu angle of 138.0° and a distorted square pyramidal geometry about the copper(II) ions. Similar chemistry in the more sterically hindered Lm* system yielded only the coordination polymer [Cu2(μ-Lm*)(μ-N3)2(N3)2]. Attempts to prepare a dinuclear complex with a bridging iodide yield the copper(I) complex [Cu5(μ-I4)(μ-Lm*)2]I3. The complexes 1 and 3 show strong antiferromagnetic coupling, -J = 135 and 161 cm(-1), respectively. Electron paramagnetic resonance (EPR) studies coupled with density functional theory (DFT) calculations show that the exchange interaction is transmitted through the dz(2) and the bridging ligand s and px orbitals. High field EPR studies confirmed the dz(2) ground state of the copper(II) ions. Single-crystal high-field EPR has been able to definitively show that the signs of D and E are positive. The zero-field splitting is dominated by the anisotropic exchange interactions. Complex 2 has -J = 223 cm(-1) and DFT calculations indicate a predominantly d(x(2)-y(2)) ground state.

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Section: Introductionmentioning

confidence: 99%