Synthesis, crystallographic characterization and magnetic properties of the dinuclear iron(III) complexes [Fe(OMe)(dbm)2]2 (1), [Fe(OMe)(dpm)2]2 (2), [Fe(OEt)(bpm)2]2 (3) and [Fe(OProp)(npm)2]2 (4) are reported. Complexes 1 and 2 have symmetric β-diketonate ligands dbm (dibenzoylmethanate) and dpm (dipivaloylmethanate), respectively, whereas complexes 3 and 4 contain asymmetric β-diketonate ligands bpm (benzoylpivaloylmethanate) and npm (naphthoylpivaloylmethanate), respectively. Complex 1 crystallizes in the triclinic system, space group P1̄ (No. 2), a=9.634(1), b=10.946(2), c=13.079(1) Å, α=79.95(1), β=88.01(1), γ=82.57(1)°, Z=1. Complex 2 crystallizes in the triclinic system, space group P1̄ (No. 2), a=10.980(2), b=14.255(2), c=17.979(1) Å, α=85.70(1), β=89.63(1), γ=71.65(1)°, Z=2. Compound 3 crystallizes in the monoclinic system, space group P21/c (No. 14), a=11.546(2), b=18.539(1), c=13.595(2) Å, β=113.18(1)°, Z=2. Compound 4 crystallizes in the monoclinic system, P21/c (No. 14) space group, a=13.746(2), b=18.933(2), c=14.158(2) Å, β=117.37(1)°, Z=2. Each complex consists of two iron(III) ions that are symmetrically bridged by two alkoxide groups. The antiferromagnetic couplings between the S=5/2 iron centers have been fitted by using the Hamiltonian H=JS1·S2 to give values of J=15.4(1) cm−1 with g=1.96(1) for 1, J=19.0(6) cm−1 with g=1.98(1) for 2, J=14.8(5) cm−1 with g=1.98(1) for 3 and J=18.0(5) with g=2 for 4. The structural and magnetic parameters of 1–4 and other iron(III)–alkoxo clusters synthesized in our laboratory are compared. No simple correlation exists between the isotropic exchange-coupling constant J and the average Fe–O(bridge) bond distance, whereas an approximately linear correlation is found between the J value and the Fe–O–Fe angle. The observed trend and the predictions of Extended Hückel calculations on the model [Fe(OH)H4]2 4− are compared and discussed.

Le Gall, F., FABRIZI DE BIANI, F., Caneschi, A., Cinelli, P., Cornia, A., Fabretti, A.C., et al. (1997). Synthesis, crystal structures and magnetic characterization of four beta-diketonates-alkoxides Iron(III) dimers. Dependence of the magnetic properties on geometrical and electronic parameters. INORGANICA CHIMICA ACTA, 262, 123-132 [10.1016/S0020-1693(97)05482-0].

Synthesis, crystal structures and magnetic characterization of four beta-diketonates-alkoxides Iron(III) dimers. Dependence of the magnetic properties on geometrical and electronic parameters.

FABRIZI DE BIANI, FABRIZIA;
1997

Abstract

Synthesis, crystallographic characterization and magnetic properties of the dinuclear iron(III) complexes [Fe(OMe)(dbm)2]2 (1), [Fe(OMe)(dpm)2]2 (2), [Fe(OEt)(bpm)2]2 (3) and [Fe(OProp)(npm)2]2 (4) are reported. Complexes 1 and 2 have symmetric β-diketonate ligands dbm (dibenzoylmethanate) and dpm (dipivaloylmethanate), respectively, whereas complexes 3 and 4 contain asymmetric β-diketonate ligands bpm (benzoylpivaloylmethanate) and npm (naphthoylpivaloylmethanate), respectively. Complex 1 crystallizes in the triclinic system, space group P1̄ (No. 2), a=9.634(1), b=10.946(2), c=13.079(1) Å, α=79.95(1), β=88.01(1), γ=82.57(1)°, Z=1. Complex 2 crystallizes in the triclinic system, space group P1̄ (No. 2), a=10.980(2), b=14.255(2), c=17.979(1) Å, α=85.70(1), β=89.63(1), γ=71.65(1)°, Z=2. Compound 3 crystallizes in the monoclinic system, space group P21/c (No. 14), a=11.546(2), b=18.539(1), c=13.595(2) Å, β=113.18(1)°, Z=2. Compound 4 crystallizes in the monoclinic system, P21/c (No. 14) space group, a=13.746(2), b=18.933(2), c=14.158(2) Å, β=117.37(1)°, Z=2. Each complex consists of two iron(III) ions that are symmetrically bridged by two alkoxide groups. The antiferromagnetic couplings between the S=5/2 iron centers have been fitted by using the Hamiltonian H=JS1·S2 to give values of J=15.4(1) cm−1 with g=1.96(1) for 1, J=19.0(6) cm−1 with g=1.98(1) for 2, J=14.8(5) cm−1 with g=1.98(1) for 3 and J=18.0(5) with g=2 for 4. The structural and magnetic parameters of 1–4 and other iron(III)–alkoxo clusters synthesized in our laboratory are compared. No simple correlation exists between the isotropic exchange-coupling constant J and the average Fe–O(bridge) bond distance, whereas an approximately linear correlation is found between the J value and the Fe–O–Fe angle. The observed trend and the predictions of Extended Hückel calculations on the model [Fe(OH)H4]2 4− are compared and discussed.
Le Gall, F., FABRIZI DE BIANI, F., Caneschi, A., Cinelli, P., Cornia, A., Fabretti, A.C., et al. (1997). Synthesis, crystal structures and magnetic characterization of four beta-diketonates-alkoxides Iron(III) dimers. Dependence of the magnetic properties on geometrical and electronic parameters. INORGANICA CHIMICA ACTA, 262, 123-132 [10.1016/S0020-1693(97)05482-0].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/23429
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