94483-24-6Relevant academic research and scientific papers
Synthesis of pure iron(II) mesotetraphenylchlorin complexes via a versatile general method of iron insertion into chlorins
Kobeissi, Marwan,Cherry, Khalil,Faraj, Mahmoud K.,Simonneaux, Gérard
, p. 30 - 34 (2013/05/09)
An original synthesis of pure (tetraphenylchlorinato)iron(III) chloride (1) is reported. Insertion of iron is achieved using 1.2 equivalents of cadmium acetate in DMF at 110 °C, followed by a transmetallation reaction (in situ) using 8 equivalents of iron(II) chloride tetrahydrate in acetone at 60 °C. The 1H NMR shifts at 25 °C of the pyrrole protons varied from 60 to 100 ppm. The absence of the signal at 80 ppm related to undesired (tetraphenylporphirinato)iron(III) chloride is a purity criterion and shows the importance of the method used. Reaction of (tetraphenylchlorinato)iron(III) chloride (1) with four equivalents of tert-butyl isocyanide, 2,6-xylyl isocyanide and dimethylphenylphosphine in the presence of zinc amalgam in dichloromethane (DCM) afforded pure FeII(TPC)(t-BuNC)2 (2), FeII(TPC)(2,6-xylylNC)2 (3) and Fe II(TPC)[P(Me)2Ph]2 (4) respectively.
NMR and EPR studies of chloroiron(iii) tetraphenyl-chlorin and its complexes with imidazoles and pyridines of widely differing basicities
Cai, Sheng,Shokhireva, Tatjana Kh.,Lichtenberger, Dennis L.,Walker, F. Ann
, p. 3519 - 3531 (2008/10/09)
The NMR and EPR spectra of two bisimidazole and three bispyridine complexes of tetraphenylchlorinatoiron(III), [(TPC)Fe(L)2]+ (L = Im-d4, 2-MeHIm, 4-Me2NPy, Py, and 4-CNPy), have been investigated. The full resonance assignments of the [(TPC)Fe(L) 2]+ complexes of this study have been made from correlation spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy (NOESY) experiments and Amsterdam density functional (ADF) calculations. Unlike the [(OEC)Fe(L)2]+ complexes reported previously (Cai, S.; Lichtenberger, D. L.; Walker, F. A. Inorg. Chem. 2005, 44, 1890-1903), the NMR data for the [(TPC)Fe(L)2]+ complexes of this study indicate that the ground state is S = 1/2 for each bisligand complex, whereas a higher spin state was present at NMR temperatures for the Py and 4-CNPy complexes of (OEC)Fe(III). The pyrrole-8,17 and pyrroline-H of all [TPCFe(L)2]+ show large magnitude chemical shifts (hence indicating large spin density on the adjacent carbons that are part of the π system), while pyrrole-12,13-CH2 and -7,18-CH2 protons show much smaller chemical shifts, as predicted by the spin densities obtained from ADF calculations. The magnitude of the chemical shifts decreases with decreasing donor ability of the substituted pyridine ligands, with the nonhindered imidazole ligand having slightly larger magnitude chemical shifts than the most basic pyridine, even though its basicity is significantly lower (4-Me2NPyH+ pKa = 9.7, H2Im + pKa = 6.65 (adjusted for the statistical factor of 2 protons)). The temperature dependence of the chemical shifts of all but the 4-Me2NPy bisligand complexes studied over the temperature range of the NMR investigations shows that they have mixed (dxy) 2(dxz,dyz)3/(dxzd yz)4(dxy)1 electron configurations that cannot be resolved by temperature-dependent fitting of the proton chemical shifts, with an S = 3/2 excited state in each case that in most cases lies at more than kT at room temperature above the ground state. The observed pattern of chemical shifts of the 4-CNPy complex and analysis of the temperature dependence indicate that it has a pure (dxzdyz) 4(dxy)1 ground state and that it is ruffled, because ruffling mixes the a2u(π)-like orbital of the chlorin into the singly occupied molecular orbital (SOMO). This mixing accounts for the negative chemical shift of the pyrroline-H (-6.5 ppm at -40°C) and thus the negative spin density at the pyrroline-α-carbons, but the mixing is not to the same extent as observed for [(TPC)Fe(t-BuNC)2]+, whose pyrroline-H chemical shift is -36 ppm at 25°C (Simonneaux, G.; Kobeissi, M. J. Chem. Sac., Dalton Trans. 2001, 1587-1592). Peak assignments for high-spin (TPC)FeCl have been made by saturation transfer techniques that depend on chemical exchange between this complex and its bis-4-Me2NPy adduct.
Comparison of Variable-Temperature 1H NMR Spectra of Five-Coordinate High-Spin (S=5/2) Iron(III) Porphyrins and Chlorins
Pawlik, M. J.,Miller, P. K.,Sullivan, E. P.,Levstik, M. A.,Almond, D. A.,Strauss, S. H.
, p. 3007 - 3012 (2007/10/02)
Variable-temperature 1H NMR spectra are reported for five different five-coordinate high-spin (S=5/2) iron(III) chlorin complexes.The complexes are Fe(TPC)X (X-=Cl-, OTeF5-) and Fe(OEC)X (X-=Cl-, OTeF5-, NCS-), where TPC=tetraphenylchlorinate dianion and OEC=octaethylchlorinate dianion.For completeness, variable-temperature spectra are also reported for the five homologous porphyrin complexes, although with one exception, Fe(OEP)(NCS), these porphyrin data have been reported by others.Spectra and Curie plots for the two classes of complexes are compared and spectral characteristics that are unique to chlorins are discussed.Our data show that the various types of pyrrole protons in the TPCcomplexes and the various types of pyrrole methylene protons in the OEC complexes exhibit a large range of isotropic shifts, ca. 30 ppm at ca. 300 K.The average temperature dependence of the resonances (i.e., Curie plot slopes) is similar to the temperature dependence of the resonance(s) for porphyrin protons in chemically similar positions.For both sets of chlorin complexes, pyrroline proton or methylene proton isotropic shifts are substantially smaller than pyrrole isotropic shifts, while pyrroline proton or methylene proton line widths are larger than pyrrole proton line widths.Large deviations in Curie plot 1/T=0 intercepts from diamagnetic chemical shifts are observed for many of the chlorin proton resonances.This behavior has been observed for all paramagnetic iron(II,III) hydroporphyrins studied to date.The different axial ligands greatly influence the range of isotropic shifts for the pyrrole protons or pyrrole methylene protons for a given chlorin and the temperature dependence (Curie plot slopes and intercepts) of the pyrroline protons for the TPC complexes.
