Change in the Spin State of an Fe
<sup>III</sup>
Center upon One N‐to‐O Switch in the Coordination of a 2,6‐Pyridinedicarboxamido Unit: The Effect of Methyl Thioether and Methyl Ether Appendages at the Ligand Periphery
作者:Todd C. Harrop、Laurie A. Tyler、Marilyn M. Olmstead、Pradip K. Mascharak
DOI:10.1002/ejic.200390067
日期:2003.2
of all four carboxamido nitrogens to the FeIII center in [Fe(PyPOMe)2]− giving rise to an FeN6 chromophore. This one N-to-O switch in donor atom makes the two complexes 1 and 2 very different. While complex 2 is low spin (g = 2.18, 1.94) much like the other reported FeIII bis complexes with two ligated 2,6-pyridinedicarboxamido units, complex 1 is high spin (g = 4.3). The spin flip due to a switch in
带有 2,6-吡啶二甲酰胺单元的两个配体,即 PyPSMeH2 和 PyPOMeH2,已被用于制备结构表征的 FeIII 复合物。由于硫醚基团对 FeIII 中心的弱亲和力,潜在的五齿硫醚配体 PyPSMeH2 仅提供双配合物 (Et4N)[Fe(PyPSMe)2] (1),而与金属与配体的比例无关。在 [Fe(PyPSMe)2]− 中,两个 PyPSMe2− 配体以单体方式与铁中心结合,硫醚侧基之间的空间拥挤迫使四个去质子化的甲酰氨基部分之一通过羰基氧与 FeIII 中心结合,产生 FeN5O 发色团。三齿配体 PyPOMeH2,以其去质子化形式,也产生双复合物,(Et4N)[Fe(PyPOMe)2] (2),其中两个 PyPOMe2− 配体以 mer 方式与铁中心结合。然而,在这种情况下,较小的侧醚基团之间较少的空间拥挤允许所有四个甲酰胺氮结合到 [Fe(PyPOMe)2]- 中的 FeIII