Bent and Linear Forms of the (μ‐Oxo)bis[trichloroferrate(III)] Dianion: An Intermolecular Effect − Structural, Electronic and Magnetic Properties

Abstract

We have analyzed the great diversity of Fe−O−Fe angles, 140−180°, found in the X‐ray structures of the (μ‐oxo)bis[trichloroferrate(III)] dianion [Cl3FeOFeCl3]2− from both experimental and theoretical points of view. Theoretical calculations show that only the linear isomer is found as a minimum on the potential energy surface. Detailed analysis of the crystal packing indicates that the angular form is due to attractive intermolecular interactions. Analysis of a selected reduced set of the 45 crystal structures retrieved from the Cambridge Structural Database allowed us to classify the bending of the [Cl3FeOFeCl3]2− dianion in three categories, depending on the balance and strength of the intermolecular O···H−X contacts. A crystal diffraction study on the bis(benzyltrimethylammonium) salt has shown both bent (144.6°) and linear (180°) forms of the (μ‐oxo)bis[trichloroferrate(III)] dianion. The magnetic susceptibility of this compound has been fitted by assuming two equally weighted contributions (Jang and Jlin) of the two forms, considering Jang − Jlin estimated by theoretical calculations. The obtained Jang and Jlin of −117 and −133 cm−1 respectively, agree well with B3LYP results. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Fe2OCl62−Salt Formed by Electrochemical Oxidation of Ethylenedioxytetrathiafulvalenoquinone-1,3-dithiolemethide in the Presence of FeCl4−Ion with a Silicon Wafer Electrode

“…As shown in Figure , the Fe 2 OCl 6 2− ion has a completely linear Fe−O−Fe bridge. This linear geometry is very rare, although a few examples have previously been reported, but an orientational disorder has been recognized, except for one Fe−O−Fe bridge . The observed Fe−O distance is 1.76 Å, comparable to the values reported so far.…”

“…The observed χ p − T behavior can be reproduced considerably well by considering contributions of both impurity spins, obeying a Curie−Weiss law with Curie constant C = 0.05 emu K mol −1 and Weiss temperature θ = +3 K, and Fe III ( S = 5 / 2 ) d spins, obeying a dimer model with a spin-exchange integral ( J ∼ −180 K) in each Fe 2 OCl 6 2− ion (see Figure ). The J value in the present Fe 2 OCl 6 2− ion is comparable with that (−191 K) in the known Fe 2 OCl 6 2− ion with a linear Fe−O−Fe bridge . Nevertheless, the fit between the observed and J = −180 K curves in the χ p − T plot is still not good.…”

Synthesis and Properties of Ba6Fe2Te3S7, with an Fe Dimer in a Magnetic Singlet State

“…The magnetic properties of the dimeric magnetic species are typically described by the isotropic spin-exchange Hamiltonian H = −2 J S 1 · S 2 . Using the Van Vleck formula (eq ) with S 1 = S 2 = 5/2 affords ,,− χ normalM = 2 N normalA g 2 μ B 2 k normalB T [ e 2 x + 5 e 6 x + 14 e 12 x + 30 e 20 x + 55 e 30 x 1 + 3 e 2 x + 5 e 6 x + 7 e 12 x + 9 e 20 x + 11 e 30 x ] ( 1 − p ) + 35 N normalA μ B 2 3 k normalB ( T − θ ) p …”

“…The magnetic properties of the dimeric magnetic species are typically described by the isotropic spin-exchange Hamiltonian H = −2 J S 1 · S 2 . Using the Van Vleck formula (eq ) with S 1 = S 2 = 5/2 affords ,,− where , N A is the Avogadro constant, g is a g -factor (fixed to 2 in our fitting to avoid overparameterization), μ B is the Bohr magneton, k B is the Boltzmann factor, T is the temperature in Kelvin, p is the fraction of magnetic Fe 3+ impurities, and J is the magnetic coupling constant. TIM is a temperature independent of paramagnetic contribution.…”

Iron and Cobalt Diazoalkane Complexes Supported by β-Diketiminate Ligands: A Synthetic, Spectroscopic, and Computational Investigation

“…The AO contributions to the corresponding pairs in 1-Fe-DFT and 3-Co-DFT clearly show that the α-spin orbital is metal based (83% and 84%, respectively) while the β-spin orbital is located on the diazoalkane moiety (76% and 77%, respectively). Broken symmetry calculations, as developed by Noodleman, were performed on these two compounds, and converged to match the unrestricted calculation. Spin density plots of 1-Fe-DFT , 1-Co-DFT and 3-Co-DFT are almost indistinguishable from each other and feature significant β-spin density on the NNC unit of the diazoalkane ligand (for 1-Fe-DFT see Figure ; for 1-Co-DFT and 3-Co-DFT see Supporting Information Figures S28 and S29, respectively).…”