A Dihydroxo-Bridged Ferric Dimer

Recent investigations have produced a large number of dimeric complexes containing the oxo-bridged structural unit Fe_2O^(4+). Here we report the isolation and characterization of [Fe (pic)_2OH]_2 which apparently is the first example of a crystalline iron(III) dimer which utilizes dihydroxo bridging in its coordination structure

Doping of copper(II) into the macrocyclic amine tet a: structural and spectroscopic studies

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Characterization of [dimethyl N,N'-ethylenebis(L-cysteinato)(2-)-S,S']copper(II), a stable copper(II) aliphatic dithiolate

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Simultaneous pair electronic excitations in a binuclear iron(III) complex

The ultraviolet absorption spectrum of an isolated metal complex containing the bridging unit Fe(III)⋯O-Fe(III) shows several bands due to the simultaneous electronic excitation of the two Fe(III) centers. The band positions are in excellent agreement with calculated sums of one-center d-d transitions

Characterization of [rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane]copper(II) 3-sulfidopropionate dimethanolate, [Cu(tet b)SCH<SUB>2</SUB>CH<SUB>2</SUB>CO<SUB>2</SUB>]&#183;2CH<SUB>3</SUB>OH, a stable copper(II)-aliphatic thiolate complex

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Magnetic Behavior and Infrared Spectra of Jarosite, Basic Iron Sulfate, and Their Chromate Analogs

The magnetic behavior and infrared spectroscopic features of KFe_3(SO_4)_2(OH)_6 (jarosite), (H_3O)Fe_3(SO_4)_2(OH)_6 (hydronium jarosite), KFe_3(CrO_4)_2(OH)_6, Fe(OH)SO_4 (basic iron sulfate) and Fe(OH)CrO_4 (basic iron chromate) are reported. Spectroscopic data are in accord with X-ray data which show that KFe_3(SO_4)_2(OH)_6, (H_3O)Fe_3(SO_4)_2(OH)_6, and KFe_3(CrO_4)_2(OH)_6 are isostructural with KAl_3(SO_4)_2(OH)_6 (akunite). All the species exhibit negative deviations from Curie-Weiss behavior over the temperature range 300-76°K. The compounds KFe_3(CrO_4)_2(OH)_6 and Fe(OH)CrO_4 undergo ferrimagnetic transitions at 73 and 71°K, respectively. Maxima occur in the susceptibilities of KFe_3(SO_4)_2(OH)_6 and (H_3O)Fe_3(SO_4)_2(OH)_6 at 45 and 50°K

Electronic Structure of Oxo-Bridged Iron(III) Dimers

Magnetic susceptibility results and extensive electronic, infrared, and Mi:issbauer spectral data are presented for enH_2[(FeHEDT A)_2O]· 6H_2O_3, Na_4[(FeEDTA)_2O]· 12H_2O, FeHEDTA· H_2O, and NaFeEDT A· 3H_2O (HEDTA = N-hydroxoethylethylenediaminetriacetate, EDTA = ethylenediaminetetraacetate, and enH_2^(2+) = ethylenediammonium cation). The magnetic and spectral data establish an electronic structural model for the oxo-bridged dimers in which pairs of S = 5/2 Fe(III) ions interact antiferromagnetically, with J ≃ -95 cm^(-1). The oxo-bridged dimers show marked intensity enhancement of the one-center Fe(III) ligand-field bands. There are also several uv bands which are interpreted as arising from simultaneous electronic excitations of Fe(III) pairs. A simple high-spin ligand-field model modified by spin-spin interaction is judged to be considerably more appropriate than the Dunitz-Orgel molecular orbital approach as a vehicle for describing oxo-bridged Fe(IIl) dimers