title: Synthesis and spectral characterization of some oxo-centered, trinuclear mixed-valence iron thiocarboxylates.
abstract: Some mixed-valence Fe(II) Fe(III) complexes of thiocarboxylic acids and straight chain fatty acids with general formula [Fe(II)Fe(III)(2)O(SOCR)(6)(H(2)O)(3)] and [Fe(II)Fe(III)(2)O(SOCR)(3)(OOCR')(3)(CH(3)OH)(3)] (where, R=CH(3) or C(6)H(5) and R'=C(13)H(27), C(15)H(31) or C(17)H(35)) were synthesized and characterized by elemental analyses, spectral (infrared, electronic and Mössbauer) studies, molar conductance and magnetic susceptibility measurements. The infrared spectra suggested bridging nature of carboxylate and thiocarboxylate anions along with upsilon(asym)(Fe(3)O) vibrations in the complexes. Mössbauer studies revealed two resolved quadrupole doublets at 120-315 K confirming the presence of Fe(II) and Fe(III) moieties in the complexes. This was supported by the observed electronic spectral bands in the complexes at room temperature. The spectrum showed a band at around 13,800 cm(-1) which indicated an intervalence-transfer. Magnetic susceptibility measurements showed weak antiferromagnetic coupling related to mixed-valence pairs with S(2)=2, em leader S(1)=S(3)=5/2 spin exchange model. Conductance data indicated, the complexes were non-electrolytes in nitrobenzene. A structure has been established on the basis of these studies.
authors.affiliation: Coordination Chemistry Laboratory, Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273 009, India. drbpbaranwal@yahoo.com
authors.forename: B P
authors.initials: BP
authors.lastname: Baranwal
authors.forename: Tarkeshwar
authors.initials: T
authors.lastname: Gupta
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008280:Magnetics; D008670:Metals / Q000737:chemistry; D008956:Models, Chemical; D013055:Spectrophotometry, Infrared; D015204:Spectroscopy, Mossbauer; D013696:Temperature
chemical_list: D002264:Carboxylic Acids; D004573:Electrolytes; D008024:Ligands; D008670:Metals; D007501:Iron