Iron octaethyltetraazaporphyrins: synthesis, characterization, coordination chemistry, and comparisons to related iron porphyrins and phthalocyanines

Abstract

bOtl 500 600 700 nm Figure 6. [MnClI2TMPS-PVPMe+] [TsO-] (dotted lines) in Vaseline.(from 497 to 490 nm) as expected for the coordination of a nitrogencontaining ligand to a manganese por~hyrin.2~Prepantion of [(n-Bu),NJHSO,. Tetra-n-butylammonium monopersulfate was prepared from the potassium salt using the procedure published by Trost et al. with some modifications.26 A 2.0-g sample of potassium monopersulfate (6.5 "01) in 20 mL of water was stirred with 2.0 g of tetra-n-butylammonium hydrogen sulfate (5.9 mmol) for 20 min. Then the solution was extracted with 40 mL of dichloromethane. This organic phase was dried over magnesium sulfate and filtered out. After evaporation, the remaining paste was washed with 10 mL of hexane and dried under vacuum. After evaporation, 0.5 g of [(~-Bu)~N]HSO!, was UV-visible spectra of MnCllzTMPS (full lines) and (25) Kelly, S. L.; Kadish, K. M. Inorg. Chem. 1982, 21, 3631-3639. (26) Trost, B. M.; Braslau, R. J . Org. Chem. 1988, 53, 532-537.obtained with a purity better than 90% (determined by icdometric titration). Ckutiolr: this peroxide should be considered as potentially explosive, and despite the repeated number of safe syntheses, we never overpassed this preparation scale.Typical Proccdure for Cyclooctew Epoxidrtioos Catalyzed by Sup ported Maqanes Porphyria Complexes. A 5-mL flask was loaded with 3 mL of dichloromethane, 20 pL of cyclooctene (154 pmol), 20 pL of 1,2-dichlorobenzene (178 pmol) as internal standard for GC analyses, and 2 pmol of sulfonated manganese porphyrin loaded on 100 mg of PVP (or 2 pmol of sulfonated manganese porphyrin for -250 mg of loaded and protonated or methylated PVP rain). At time zero, 165 mg of PhIO (750 pmol) was added to the stirred reaction mixture. At different reaction times the stirring was stopped to allow the uptake of an aliquot of 1 pL, which was directly analyzed by GC. Concentrations of cyclooctene and cyclooctene oxide were determined after their corresponding response factors. Results described in Figure 5 were obtained starting with 500 pL of cyclooctene (3850 pmol). Typical Procedure for A d a~n t r a e Hydroxylations Catalyzed bySupported l b n p w e Porphyria Cmpkxea. A IO-mL flask was loaded with 525 mg of adamantane (3.86 mfiol), 120 mg of 1,4dibromobenzene (internal standard), 1 pmol of the supported catalyst, and 7 mL of dichloromethane (1 pmol of the supported catalyst equals a loading of 1 pmol of MnCll2TMPS for 100 mg of PVP in the case of [MnCIl2TMPS-PVP], or for -250 mg of [MnCll2TMPS-PVPH+]-[TsO-] or [MnC1lzTMPS-PVPMe+] [TsO-1). At time zero, 165 mg of PhIO (750 pmmol) was added to the stirred reaction mixture at room temperature under air (results were not modified when performed in an argon atmosphere). Aliquots of 1 pL were directly analyzed by GC. Concentrations of 1-admantanol, 2-adamantanol, and adamantanone were determined after their corresponding response factors.Ackmwledgmeat. This work was supported by a "Stimulation" grant from the EEC, including a postdoctoral fellowship for S.C.(on leave from Prs. G....

Iron Chelates of 2,2′‐Bidipyrrin: Stable Analogues of the Labile Iron Bilins

“…The FeÀN and FeÀCl bond lengths observed for 2 are, however, similar to those reported for the chloridoiron complex of tetraazaporphyrin, [37] which is reported to contain a S = 3/2 ironA C H T U N G T R E N N U N G (III) ion in square-pyramidal coordination, and the bond lengths of the coordination polyhedron of the iodido derivative 7 are reminiscent of those found for an iodido iron porphycene in a S = 3/2 spin state with a tiny amount of S = 5/2 admixture. [36] The characteristic helicity and the intramolecular strain of metal chelates of open-chain tetrapyrroles is clearly present in 6, as quantified by the dihedral angle N1-N2-N3-N4 of 18.428, albeit less pronounced than in the known pentacoordinate chloridoiron complex 1 of the oxidized a,w-dioxobilin ligand (26.438).…”

Bonding Characteristics Mediated by Saddle-Shaped Porphyrin Deformation: A Theoretical Approach to the Control of Spin State of Iron(III) Porphyrins

“…Following this trend, it should be possible to increase the contribution of intermediate-spin state of iron(iii) by further increase the basicity of porphyrin macrocycle. Porphyrin basicity may be increased by strongly electron donating substituents that add directly to the porphyrin macrocycle, core size contraction of porphyrin macrocycle, [13] or through saddle-shaped deformation of porphyrin macrocycle, [25,26] which seems to be less intuitively obvious. It is our expectation to obtain a direct mechanistic link between the structural feature and a change in iron spin state from molecular orbital calculations.…”

“…[9] [10] Nearly pure intermediate-spin (S 3/2) iron(iii) complexes have been reported for phthalocyanines [11,12] and tetraazaporphyrin. [13] It is widely accepted that it is the smaller hole of the macrocycle that makes the systems unusual. Quantum mechanically mixed intermediate-spin states (S 5/2, 3/2) have been proposed for certain cytochromes c' and also for horseradish peroxidase.…”

Synthesis and Study of the Binuclear μ‐Oxodiiron(III) Complexes of 5‐Monoaza‐ and 5,15‐Diaza‐Substituted β‐Octaalkylporphyrins

“…Chemical shifts in the 1 H NMR spectra of β-octaalkyl-substituted porphyrin and meso-azaporphyrins and their five-coordinate mononuclear and binuclear μ-oxo-bridged iron(III) complexes at ambient temperature. [14] [a] This work. exerting a slight shift to the opposite high-field direction are observed at δ = 1.9, 1.5-1.6 and 1.1 ppm (for β-CH 2 , γ-CH 2 and δ-CH 3 , respectively).…”

“…Previously, the kinetics and mechanism of such "dissociation" behaviour have been studied for μ-oxo dimers of the phenyl-substituted Fe III porphyrins meso-tetraphenylporphine [μ-O(FeTPP) 2 ] [8] and β-octaphenyltetraazaporphine [μ-O(FeOPTAP) 2 ] [9] in benzene solution in the presence of acetic and trichloroacetic acids. The synthesis and spectral properties of μ-oxo dimers formed from the β-alkyl-substituted Fe III porphyrins β-octaethylporphine [μ-O(FeOEP) 2 ] [10][11][12][13] and β-octaethyltetraazaporphine [μ-O(FeOETAP) 2 ] [14] have also been reported. Mononuclear Fe III complexes are also known for forming β-alkylsubstituted meso-monoazaporphyrins [15][16][17][18][19] and meso-diazaporphyrins, [18][19][20][21][22] however, to the best of our knowledge, their binuclear μ-oxo species have not been characterised.…”