Relative Axial Ligand Orientation in Bis(imidazole)iron(II) Porphyrinates: Are “Picket Fence” Derivatives Different?

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• 作者：Jianfeng Li ; Smitha M. Nair ; Bruce C. Noll ; Charles E. Schulz ; W. Robert Scheidt
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：May 5, 2008
• 年：2008
• 卷：47
• 期：9
• 页码：3841 - 3850
• 全文大小：5060K
• 年卷期：v.47,no.9(May 5, 2008)
• ISSN：1520-510X

文摘

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 α,α,α,α-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°, 62.4°, and 78.5°. 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.