ja904368n_si_002.cif (26.04 kB)
Iron-Porphyrin NO Complexes with Covalently Attached N-Donor Ligands: Formation of a Stable Six-Coordinate Species in Solution
dataset
posted on 2009-12-02, 00:00 authored by Timothy C. Berto, V. K. K. Praneeth, Lauren E. Goodrich, Nicolai LehnertA series of substituted tetraphenylporphyrin type macrocycles (TMP or To-F2PP) with covalently attached N-donor ligands (pyridine or imidazole linker) have been synthesized. Linkers with varying chain lengths and designs have been applied to systematically investigate the effect of chain length and rigidity on the binding affinity of the linker to the corresponding Fe(II)−NO heme complexes. The binding of the linker is monitored in solution using a variety of spectroscopic methods including UV−vis absorption, EPR, and IR spectroscopy. Both the N−O stretching frequency and the imidazole 14N hyperfine coupling constants show a good correlation with the Fe−(N-donor) bond strength in these systems. The complexes with covalently attached pyridyl and alkyl imidazole ligands only exhibit weak interactions of the linker with iron(II). However, the stable six-coordinate complex [Fe(To-F2PP-BzIM)(NO)] (4) is obtained when a rigid benzyl linker is applied. This complex exhibits typical properties of six-coordinate ferrous heme-nitrosyls in which an N-donor ligand is bound trans to NO, including the Soret band at 427 nm and the typical nine line 14N hyperfine splitting in the EPR spectrum. A crystal structure has been obtained for the corresponding zinc complex. Here, we report the first systematic study on the requirements for the formation of stable six-coordinate ferrous heme nitrosyl complexes in solution at room temperature in the absence of excess axial N-donor ligand.
History
Usage metrics
Categories
Keywords
2PPline 14 Nchain lengthschain lengthconstants showhemesolutionbenzyl linkerSolutionA seriesalkyl imidazole ligandsimidazole 14 NEPR spectrumferrouUVTMProom temperaturecrystal structuretetraphenylporphyrin type macrocyclesFespectroscopic methodsbinding affinitycovalentlyexhibit427 nmIR spectroscopycompleximidazole linkerSoret band
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC