Li Jianfeng, Nair Smitha M, Noll Bruce C, Schulz Charles E, Scheidt W Robert
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
Inorg Chem. 2008 May 5;47(9):3841-50. doi: 10.1021/ic702498c. Epub 2008 Mar 20.
The synthesis of three new bis(imidazole)-ligated iron(II) picket fence porphyrin derivatives, [Fe(TpivPP)(1-RIm) 2] 1-RIm = 1-methyl-, 1-ethyl-, or 1-vinylimidazole) are reported. X-ray structure determinations reveal that the steric requirements of the four alpha,alpha,alpha,alpha-o-pivalamidophenyl groups lead to very restricted rotation of the imidazole ligand on the picket side of the porphyrin plane; the crowding leads to an imidazole plane orientation eclipsing an iron-porphyrin nitrogen bond. An unusual feature for these diamagnetic iron(II) species is that all three derivatives have the two axial ligands with a relative perpendicular orientation; the dihedral angles between the two imidazole planes are 77.2 degrees , 62.4 degrees , and 78.5 degrees . All three derivatives have nearly planar porphyrin cores. Mössbauer spectroscopic characterization shows that all three derivatives have quadrupole splitting constants around 1.00 mm/s at 100K.
报道了三种新型双（咪唑）连接的铁（II）栅栏卟啉衍生物[Fe（TpivPP）（1-RIm）2]（1-RIm = 1-甲基-、1-乙基-或1-乙烯基咪唑）的合成。X射线结构测定表明，四个α，α，α，α-邻新戊酰胺基苯基的空间需求导致卟啉平面栅栏侧的咪唑配体旋转非常受限；空间拥挤导致咪唑平面取向与铁-卟啉氮键重叠。这些抗磁性铁（II）物种的一个不寻常特征是，所有三种衍生物的两个轴向配体都具有相对垂直的取向；两个咪唑平面之间的二面角分别为77.2度、62.4度和78.5度。所有三种衍生物都具有近乎平面的卟啉核心。穆斯堡尔光谱表征表明，所有三种衍生物在100K时的四极分裂常数约为1.00 mm/s。
