Redetermination of the structure of porphine

Chen, Betty M. L.; Tulinsky, A.

doi:10.1021/ja00767a015

Cited by 185 publications

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“…It has D 2h symmetry [6] which has been confirmed with theoretical methods including electron correlation treatment. Hartree-Fock calculations predict a C 2v symmetric structure [7,8].…”

Section: Introductionmentioning

confidence: 60%

Structure and binding energies of the porphine dimer

Mück‐Lichtenfeld¹

2007

Molecular Physics

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“…It has D 2h symmetry [6] which has been confirmed with theoretical methods including electron correlation treatment. Hartree-Fock calculations predict a C 2v symmetric structure [7,8].…”

Section: Introductionmentioning

confidence: 60%

Structure and binding energies of the porphine dimer

Mück‐Lichtenfeld¹

2007

Molecular Physics

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“…Similarly in the recent determination of the structure of the free base of octaethylporphyrin (Lauher & Ibers, 1973) the center-methine carbon atom distance is 3.42 .~, while in various meso-substituted free base porphyrins this distance varies from 3.44-3.45/~ (Codding & Tulinsky, 1972;Silvers & Tulinsky, 1967). In the tetragonal form of tetraphenylporphyrin (Hamor, Hamor & Hoard, 1964) this distance is the same as in octaethylporphyrin and as in porphine itself (Chen & Tulinsky, 1972).…”

Section: Determination and Refinement Of The Structurementioning

confidence: 83%

Crystal and molecular structure of 1,2,3,4,5,6,7,8-octaethylporphinatodichlorotin(IV) nitromethane solvate

Cullen¹,

Meyer²

1973

Acta Crystallogr Sect B

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2507of the ThzNilv-type structure decreases. This suggests that the degree of order of the ThzNi17-type structures of Pr2C017 and NdzC017 is lowest. Therefore, the ThzNi~v-type compounds for these R elements do not exist. The degree of order of the ThzNi~7-type structures of Ce2C0~7 and Ho2Co17 is nearly ideal. One therefore gets only traces of the ThzZnlv-type structure even after prolonged annealing at lower temperatures. Dy2C017 appears to lie in between these two extreme cases. This is the reason that both modifications i.e.ThzNit7+ThzZnlv-type, are obtained in almost equal proportions below 1200°C.Since those R elements, studied in this work are uniformly distributed throughout the whole rare-earth series, the results obtained for their AzB17 compounds can generally be applied to all the RzCox7 compounds (Fig. 1). Buschow (1966) and Givord, Givord & Lemaire (1972) have explained the polymorphism of RzCo~v in terms of the radii ratios of R and Co atoms. No doubt the atomic radii of R and Co atoms are important factors in the formation of RECO~7. However, the atomic ratio model alone cannot explain the polymorphism of R2Co17 over the rare-earth series and the degree of order of R2Co17 of the Th2Ni17-type structure.In our opinion, the valence-electron concentration and the electron-spatial correlation play a deciding role in the stabilization of one or more of the polymorphic forms of R2C0~7 for a particular R element at a particular temperature.

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“…These distortions lead to a saddle conformation of the porphyrinoid skeleton similar to those observed for pyrrole-substituted tetraphenyl porphyrins (Bhyrappa, Nethaji & Krishnan, 1993;Mandon et al, 1992). The inner imino H atoms are positioned trans to each other on the pyrrole rings not bearing the nitro groups with N--H distances of 1.10 (9) and 0.96 (9) A (Silvers & Tulinsky, 1967;Chen & Tulinsky, 1971). The phenyl rings adjacent to the nitro groups are rotated by 36.5 (3) and 38.6 (4) ° from the mean N4 plane so as to avoid the steric influence of the nitro groups at positions 3 and 12 of the macrocycle.…”

mentioning

confidence: 69%

3,12-Dinitro-5,10,15,20-tetraphenylporphyrin – an example of a twisted intramolecular charge-transfer system

Dahal¹,

Nethaji²,

Krishnan³

1994

Acta Crystallogr C

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The porphyrin ring in the title compound, 10,19-dinitro-2,7,12,17-tetraphenyl-21,22,23,24-tetraazapentacyclo[ 16.2.1.13'6.18'11 . 1 ~3'16]tetracosa-1,3,5,7,9,11 (23) S. DAHAL, M. NETHAJI AND V. KRISHNAN 315 12,14,16,18(21), 19-undecaene 0.5-dichloromethane solvate, C44H28N604.0.5CH2C12, adopts a saddle conformation with neighbouring pyrrole rings tilted with respect to each other. The two nitro groups are situated on alternate pyrrole rings and have their planes angled away from those of the pyrrole rings, thereby indicating that interaction between the porphyrin and nitro groups is slight. CommentNitro porphyrins offer interesting systems for the study of intramolecular charge-transfer states (Gust et al., 1990;Takahashi, Hase, Komura, Imanaga & Ohno, 1992;Rettig, 1986). Structure analysis of the title compound (I) was carried out to determine the orientation of the nitro groups with respect to the porphyrin plane. This structural feature is important to an understanding of the type and magnitude of charge transfer that takes place in the excited state of the system. Moreover, tetraphenyl porphyrins bearing substitutents at the pyrrole C atoms exhibit interesting conformational features 1991; Barkigia et al., 1990;Mandon et al., 1992). Details of the synthetic work will be published elsewhere (Dahal & Krishnan, 1993). The structure of (I) is found to be severely nonplanar with an average deviation of 0.36 A from the mean N 4 plane (the plane passing through the four N atoms of the pyrrole rings). Neighbouring pyrrole rings of the macrocycle are tilted by 26.5 (5), 27.4(5), 18.4(4) and 14.8 (4) ° with respect to each other, while the opposite pyrroles are tilted by 32.5 (4) and 25.1 (5) ° with respect to each other. The displacements of the meso C atoms, C5, C10, C15 and C20 from the mean N4 plane are -0.15 (1), -0.03 (1), -0.02 (1) and 0.21 (1)A, respectively. These distortions lead to a saddle conformation of the porphyrinoid skeleton similar to those observed for pyrrole-substituted tetraphenyl porphyrins (Bhyrappa, Nethaji & Krishnan, 1993;Mandon et al., 1992). The inner imino H atoms are positioned trans to each other on the pyrrole rings not bearing the nitro groups with N--H distances of 1.10 (9) and 0.96 (9) A (Silvers & Tulinsky, 1967;Chen & Tulinsky, 1971). The phenyl rings adjacent to the nitro groups are rotated by 36.5 (3) and 38.6 (4) ° from the mean N4 plane so as to avoid the steric influence of the nitro groups at positions 3 and 12 of the macrocycle. The other two phenyl rings are rotated by 88.6 (4) and 54.5 (4) ° from the mean N4 plane. The planes of the nitro groups are tilted by 42.2 (6) and 38.0 (9) ° with respect to those defined by the pyrrole rings to which they are attached, and deviate by 39.4 (8) and 42.1 (9) ° from the mean N4 plane of the porphyrin. The N atoms of the nitro groups are displaced by 0.27 (1) and 0.38 (1) A from the plane of the pyrrole rings to which they are attached. The nitro group rotations, coupled with their upward displacements, imply only slight ...

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Redetermination of the structure of porphine

Cited by 185 publications

References 0 publications

Structure and binding energies of the porphine dimer

Structure and binding energies of the porphine dimer

Crystal and molecular structure of 1,2,3,4,5,6,7,8-octaethylporphinatodichlorotin(IV) nitromethane solvate

3,12-Dinitro-5,10,15,20-tetraphenylporphyrin – an example of a twisted intramolecular charge-transfer system

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