| | 1 | Author
| | Requires cookie* | | | Title
| Metallkomplexe mit Tetrapyrrol-Liganden, XIV1 * Eisenporphodimethene: Sterisch und elektronisch modifizierte Häme und Hämine  | | | | Abstract
| M etal Complexes of T etrapyrrole Ligands, X IV 1 Iro n P o rp h o d im eth en es: Sterically and E lectronically Modified H em es an d H em ins J o h a n n W. B u c h l e r u n d K . L am L a y Iron An air-stable porphodimethene, namely a, y-dimethyl-a, y-dihydrooctaethylporphyrin [H 2(OÄPMe2)*; (1)] is metalated with Fe(CO)5/I2 in toluene to yield an air-stable binuclear iron(III) porphodimethene, /i-oxobis(a, y-dimethyl-a, | | | |
Reference
| (Z. Naturforsch. 30b, 385—392 [1975]; eingegangen am 27. Februar 1975) | | | |
Published
| 1975 | | | |
Keywords
| Porphyrins, Iron Porphodimethenes, Hemes, Hemins | | | |
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| default:Reihe_B/30/ZNB-1975-30b-0385.pdf | | | | Identifier
| ZNB-1975-30b-0385 | | | | Volume
| 30 | |
| 2 | Author
| Steffen Runge, M. Athias, O. Senge | Requires cookie* | | | Title
| Electron Donor-Acceptor Compounds. Synthesis and Structure of 5-(l,4-Benzoquinone-2-yl)-10,15,20-trialkylporphyrins | | | | Abstract
| A series of 5-(benzoquinone)-10,15,20-trialkylporphyrins was synthesized via cross conden sation of the respective aldehydes, 2,5-dimethoxybenzaldehyde and pyrrole followed by de-methylation with BBr3 and oxidation with P b 0 2. This method worked reasonably well for compounds bearing the benzoquinone substituent and butyl, isopropyl, 1 -methylpropyl and 2-ethylpropyl residues (2a-d). The free base porphyrin quinones were converted into the zinc(II) complexes (3a-d) all of which showed remarkable stability for porphyrin quinones. The zinc(II) complex 3c bearing isopropyl residues was investigated by X-ray crystallography and showed a supramolecular structure consisting of polymeric chains facilitated by coordina tion of a benzoquinone oxygen to a neighboring zinc(II) center. Attempts to synthesize a 5-(benzoquinone)-10,15,20-tris(terr-butylporphyrin) resulted in the formation of a yellow por-phomethene (4), which could not be oxidized further. A crystal structure analysis of 4, the first for a free base porphomethene, shows an extremely twisted conformation with syn-orientation of the three rm-butyl groups. The results indicate that new methods will have to be developed for the synthesis of nonplanar porphyrin quinones. | | | |
Reference
| Z. Naturforsch. 53b, 1021—1030 (1998); received June 15 1998 | | | |
Published
| 1998 | | | |
Keywords
| Porphyrins, Quinones, Electron Transfer Compounds, Crystal Structure, Conformation | | | |
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| default:Reihe_B/53/ZNB-1998-53b-1021.pdf | | | | Identifier
| ZNB-1998-53b-1021 | | | | Volume
| 53 | |
| 3 | Author
| Steffen Runge3, MathiasO. Senge3, Karin Ruhlandt-Sengeb | Requires cookie* | | | Title
| 5,10,15,20-Tetrakis(diphenylmethyl)porphyrin -A Nonplanar Porphyrin with Intermediate Degree of Ruffling | | | | Abstract
| The title compound was prepared by condensation of pyrrole and diphenylacetaldehyde in 16% yield. Based on spectroscopic data, the free base porphyrin exhibits a nonplanar macrocycle in solution with a degree of distortion between that of 5,10,15,20-tetracyclohexyl-porphyrin and 5,10,15,20-tetra(r-butyl)porphyrin. A crystal structure determination of the cobalt(II) complex reveals a ruffled macrocycle conformation with an average out-of-plane displacement of the m eso carbon atoms by 0.55 A. | | | |
Reference
| Z. Naturforsch. 54b, 662 (1999); received February 17 1999 | | | |
Published
| 1999 | | | |
Keywords
| Porphyrins, Steric Strain, Cobalt Porphyrins, Crystal Structure, Conformation | | | |
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| default:Reihe_B/54/ZNB-1999-54b-0662.pdf | | | | Identifier
| ZNB-1999-54b-0662 | | | | Volume
| 54 | |
| 5 | Author
| M. Athias, O. Senge, W. Erner, W. Kalisch | Requires cookie* | | | Title
| Structure and Conformation of Tetra-meso-, O c t a -ß and Dodecasubstituted 22,24-Dihydroporphyrins (Porphyrin Dications) | | | | Abstract
| A comparative crystallographic analysis of the conformation of porphyrin diacids with various substituent types reveals considerable differences in the degree of nonplanarity and distortion modes. Diacids of 5,10,15,20-tetraarylporphyrins generally exhibit typical saddle-distorted macrocycles with displacements of the Cb positions in the range of 0.7-1.0 A. Adding peripheral substituents, i.e., using dodecasubstituted porphyrins for the diacid forma tion yields similar distortion types albeit with larger out-of-plane displacements. As a result of the combined effect of both peripheral (interaction between the Cb and Cm substituents) and core (interaction between the four inner hydrogen atoms) steric strain the maximum Cb displacements reach 1.3-1.5 A. Quite a different situation is observed for the diacids of 2,3,7,8,12,13,17,18-octaalkylporphyrins. Here, macrocycles with pair-wise displacement of neighboring pyrrole rings and significant NH pyramidalization and those with classic saddle distortion are found. Generally, octa-/?-substituted porphyrin diacids show smaller degrees of nonplanarity; Cb displacements ranged from 0.06 to 0.72 A. On the basis of the overall degree of conformational distortion (ZI24 = average deviation of the 24 macrocycles atoms from the mean plane), the three different types of porphyrin macrocycles studied differ considerably in their degree of conformational flexibility. For several porphyrin crystal structures with different counterions and/or solvate molecules were obtained. Taking into account results from the literature 2,3,7,8,12,13,17,18-octaethyl-22,24-dihydro-5,10,15.,20-tetraphenylporphy-rin (13) shows the smallest degree of flexibility (ZI24 = 0.61-0.63 A; four different X-ray structures),o while 22,24-dihydro-5,10,15,20-tetraphenylporphyrin (1) is more flexible (ZI24 = 0.42-0.52 A; four structures). The largest flexibility is observed for 2,3,7,8,12,13,18-octaethyl-22,24-dihydroporphyrin (7) (A24 = 0.02-0.33 A; four structures). | | | |
Reference
| Z. Naturforsch. 54b, 943—959 (1999); received May 4 1999 | | | |
Published
| 1999 | | | |
Keywords
| Porphyrins, Steric Strain, Porphyrin Dications, Crystal Structure, 22, 24-Dihydroporphyrins | | | |
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| default:Reihe_B/54/ZNB-1999-54b-0943.pdf | | | | Identifier
| ZNB-1999-54b-0943 | | | | Volume
| 54 | |
| 6 | Author
| M. Ath, O. S. Enge | Requires cookie* | | | Title
| A Conformational Study of 5,10,15,20-Tetraalkyl-22//+,24//+-porphyrindiium Salts (Dication Salts) | | | | Abstract
| N-protonation of 5,10,15,20-tetraalkylporphyrins with n-butyl, isobutyl, isopropyl, 1-ethyl-propyl or ferf-butyl substituents yields the respective 22,24-dihydroporphyrins (22//+,24//+-porphyrindiium salts) that exhibit highly nonplanar conformations. Depending on the steric demand of the meso substituents, the free base porphyrins have planar to moderately ruffled macrocycles (primary or secondary alkyl residues) or are severely ruffled (tertiary alkyl resi dues). X-ray crystallographic studies show that protonation of porphyrins with «-Bu (2), i-Pr (3) or EtPr (4) substituents leads to steric congestion of the core resulting in symmetric, saddle distorted macrocycles as evidenced by average displacements of the Cb positions from the mean plane ranging from 0.79 to 1.01 A. The structures observed for these porphyrin diacids are very similar in distortion mode and degree of nonplanarity to 5,10,15,20-tetraaryl-22f/+,24//+-porphyrindiium salts and to 2,3,7,8,12,13,17,18-octaalkyl-5,10,15,20-tetraaryl-porphyrins. In contrast, protonation of the highly ruffled 5,10,15,20-tetrakis(teA-r-butyl)porph-yrin results in a switch of the conformational distortion mode. The dication 6 shows both saddle distortion (Cb displacements -1.3 A) and ruffling of the macrocycle (Cm displacements of approx. 0.48 A). Thus, the need to accomodate four N-H units in the porphyrin core with its associated out-of-plane tilting of the pyrrole rings and the steric strain induced at the meso carbon atoms results in a highly nonplanar porphyrin with mixed distortion modes. | | | |
Reference
| Z. Naturforsch. 55b, 336—344 (2000); received January 20 2000 | | | |
Published
| 2000 | | | |
Keywords
| Porphyrins, Steric Strain, Porphyrin Dications, Crystal Structure, Conformational Analysis, 22, 24-Dihydroporphyrins | | | |
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| default:Reihe_B/55/ZNB-2000-55b-0336.pdf | | | | Identifier
| ZNB-2000-55b-0336 | | | | Volume
| 55 | |
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