Synthesis and Relative Stability of a Series of Compounds of Type [Fe(II)(bztpen)X]+, Where bztpen = Pentadentate Ligand, N5, and X- = Monodentate Anion

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• 作者：Norma Ortega-Villar ; V&iacute ; ctor M. Ugalde-Sald&iacute ; var ; M. Carmen Mu&ntilde ; oz ; Luis A. Ortiz-Frade ; Jos&eacute ; G. Alvarado-Rodr&iacute ; guez ; Jos&eacute ; A. Real ; Rafael Moreno-Esparza
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：September 3, 2007
• 年：2007
• 卷：46
• 期：18
• 页码：7285 - 7293
• 全文大小：309K
• 年卷期：v.46,no.18(September 3, 2007)
• ISSN：1520-510X

文摘

The structural and solution characterization of novel Fe(II) compounds of the general formula [Fe(bztpen)X]PF₆and [Fe(bztpen)CH₃CN](PF₆)₂ is presented, where bztpen is the pentadentate ligand N-benzyl-N,N',N'-tris(2-methylpyridyl)ethylenediamine and X^- is a monodentate ligand. All complexes were characterized in solution andin the solid state, employing the usual techniques and single-crystal X-ray diffraction. The results obtained arediscussed in terms of the existing information for some previously reported analogous compounds to arrive at arationalization regarding the influence of a variation in the coordination environment of all compounds and to evaluatetheir relative stability. The observed magnetic response in the solid state is paramagnetic in the entire temperaturerange for the Cl^-, Br^-, I^-, OCN^-, and SCN^- derivatives, while the N(CN)₂^-, CH₃CN, and CN^- derivatives arediamagnetic. The diamagnetic character of these last two compounds is confirmed in acetonitrile solution, while aspin transition step is observed for the N(CN)₂^- derivative. Diffraction data for all compounds as hexafluorophosphatesshows that the I^-, Br^-, and OCN^- derivatives crystallize in the orthorhombic space group Pbca, while the CN^-,SCN^-, and CH₃CN compounds crystallize in the triclinic space group Pages/entities/onemacr.gif">. Average bond lengths and the trigonaldistortion parameter can be correlated to the observed magnetic susceptibility depending on the coordinatedmonodentate ligand. Solution measurements of electronic properties for the compounds follow the trend establishedby the spectrochemical series. The relative stability of the Fe(II) complexes can be established in terms of thepercentage of dissociation from the voltammetry and conductivity results, which are consistent with those obtainedspectrophotometrically, mainly, the larger stability for the CN^- derivative and the lower for the I^- derivative. Theredox potential and percentage of dissociation values allow for the estimation of the relative stability constants forthe Fe(II) and Fe(III) complexes.