2,3,7,8,12,17,18-Octaethyl-5-[2,2-bis(ethoxycarbonyl)vinyl]-22<i>H</i>,24<i>H</i>-porphine

Sheldrick, W.S.

doi:10.1107/s0567740877012631

Cited by 6 publications

(2 citation statements)

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“…Such compounds were therefore labeled “highly substituted porphyrins” − A number of reports on the synthesis of 5,15-disubstituted porphyrins have also appeared, ,, but no detailed analysis of their conformations has heretofore been performed. …”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of the Conformations of Symmetrically and Asymmetrically Deca- and Undecasubstituted Porphyrins Bearing Meso-Alkyl or -Aryl Groups

et al. 1997

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Conformational analysis of highly substituted porphyrins has potential implications for modeling the behavior of macrocycles in tetrapyrrole-containing protein complexes and during catalytic reactions. In order to study the influence of different substituent patterns on the conformation of the porphyrin macrocycle, a series of metal free and nickel(II) decasubstituted porphyrins bearing aryl or ethyl groups at opposite meso positions and alkyl groups at the pyrrole positions have been synthesized and characterized by X-ray crystallography. Crystal structures of the free-base porphyrins with 5,15-diaryl substituents showed negligible out-of-plane distortion but a large amount of in-plane distortion along the 5,15-axis accompanied by large bond angle changes similar to those previously seen for related porphyrins with 5,15-dialkyl substituents. Nickel(II) complexes of the 5,15-diaryl-substituted porphyrins show planar or modestly nonplanar conformations, suggesting that these complexes are not intrinsically nonplanar, whereas a complex with 5,15-diethyl substituents has a very ruffled conformation similar to those observed for related complexes with other metals. The nickel(II) complexes are also elongated along the 5,15-axis in a qualitatively similar but less dramatic fashion than are the free-base porphyrins. Spectrosopic studies ((1)H NMR, optical, and resonance Raman spectroscopy) suggest that conformations similar to those determined by X-ray crystallography are present in solution for the 5,15-dialkyl- and 5,15-diaryl-substituted porphyrins. Several asymmetric nickel(II) and metal-free deca- and undecasubstituted porphyrins containing both aryl and alkyl meso-substituents were also investigated. Metal-free 5,15-disubstituted porphyrins with one aryl and one alkyl group showed considerably elongated porphyrin cores, whereas nickel(II) complexes of porphyrins with 5,10- or 5,10,15-substitution patterns showed very nonplanar structures consisting mainly of ruffle and saddle type distortions.

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Section: Introductionmentioning

confidence: 99%

Comparative Analysis of the Conformations of Symmetrically and Asymmetrically Deca- and Undecasubstituted Porphyrins Bearing Meso-Alkyl or -Aryl Groups

et al. 1997

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“…The dihedral angle between the nitroheterocycle (plane 1) and plane 2 is equal to 14(4)° suggesting a strong conjugating effect all along the chains defining these two moieties. This electronic effect is one of the two stronger observed among the few examples of substituted methylenemalonate reported in the literature [4][5][6][7][8][9][10]. On another hand, the second ester arm of the diethyl malonate is quite perpendicular to the plane defined by the methylene and the first ester arm.…”

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confidence: 77%

Crystal structure of diethyl 2-( 1-methyl-5-nitro- 1H-imidazol- 4-ylmethylene)malonate, C12H15N3O6

Crozet¹,

Giorgi²,

Terme³

et al. 2005

Zeitschrift Für Kristallographie - New Crystal Structures

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C12H15N3O6, monoclinic, Pl2\/cl (no. 14), a = 14.7940 (7) Source of materialThe synthesis of diethyl 2-(l-methyl-5-nitro-l//-imidazol-4-ylmethylene)malonate has been already reported [1], In the title structure, the nitro group is almost coplanar with the heterocyclic ring. The angle between NO2 and the mean fivemembered ring plane is 5(3)°. The methylene and one ester arm of the diethyl malonate are also almost coplanar. The maximum outof-plane deviation from the mean plane C1-C10-C11-C17-018-019-C20-C21 (plane 2) is equal to 0.083(3) A. The distances and angles involving the various heteroatoms are similar to those reported in the literature [3]. The dihedral angle between the nitroheterocycle (plane 1) and plane 2 is equal to 14(4)° suggesting a strong conjugating effect all along the chains defining these two moieties. This electronic effect is one of the two stronger observed among the few examples of substituted methylenemalonate reported in the literature [4][5][6][7][8][9][10]. On another hand, the second ester arm of the diethyl malonate is quite perpendicular to the plane defined by the methylene and the first ester arm. The dihedral between plane 2 and the mean plane 013/C12/014/C15 (plane 3) is equal 96(4)°. This conformation is comparable to those reported for other substituted methylenemalonate except in one case where the dihedral angle between the two ester arms is very small due to the constraint derived from an intramolecular hydrogen bond [8]. In the title structure, the H3 atom of the heterocycle and the H5D atom of the methyl make an Η bond with the N2 atom of a symmetry-related molecule and the 08 atom of an ester arm of the same adjacent molecule, respectively (symmetry code 1-jt, l-y,2-z). Consequently, the two molecules form a dimer which is stabilized by a triple hydrogen bond, with each five-membered ring and one ester arm of each diethyl malonate lying on the same plane. Experimental detailsDisordered Η atoms at the C5 atom were found from Fourier difference maps and refined with occupation factors equal to 0.5. During the refinement they were allowed to rotate freely about the C-C bond with i/iso(H) restrained to 1.2 U e q(C).

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