Crystal and molecular structure of 8,12-diethyl-2,3,7,13,17,18-hexamethylcorrole

Abstract

The crystal structure of 8.1 2-diethyl-2.3.7.13.17.18-hexamethylcorrole has been elucidated by X-ray crystallographic analysis and the geometry of the macrocyclic ring system has been found to be not strictly planar. The distortions are probably caused by short N-N contacts brought on by the direct C(l)-C(19) link. The ' ruffling ' of the pyrrole rings is similar to that found in some substituted porphyrins, although individual ring geometries have been altered by the inner crowding. Crystallographic evidence suggests that the three inner hydrogen atoms are statistically distributed among the four nitrogen atoms. Packing is in the ' parallel disc ' mode and is specific for the molecular distortion.Laboratory, South Parks Road, Oxford DURING attempts at synthesis of the vitamin B,, corrin nucleus and assessments of the feasibility of various biosynthetic pathways for the porphyrins and corrins, Johnson and Kay2-* described the synthesis of a new macrocyclic system, corrole. This system, lacking a C (2O)meso-carbon bridge, appeared to have a corrin-type skeleton with 10 double bonds, involving porphyrin-like conjugation. The structure of Johnson's original compound (I), C,,H,,N4, 2,3,7,13,17,18-hexamethyl-8,12diethyl corrole has been elucidated by X-ray crystallographic analysis which confirms the organic synthetic conclusions. light petroleum (b.p. 40-60@) on chloroforni-corrole. The two forms were characterized as monoclinic ( P 2 J c ) with 2 = 4, a = 4-71, b = 38.15, G = 13.57 A, Q = 94-85', and orthorhombic (Pbca) with 2 = 8, a = 8.98, b = 36-96, and G = 14.57 A. Neither form contained solvent of crystal-lization. Because they were much larger, the orthorhombic crystals were used for data collection. Approximately 3000 independent reflections were measured using a computer-controlled four-circle diffractometer with nickelfiltered Cu-K, radiation. Lorentz, polarization and semiempirical absorption corrections 5 3 6 were then applied. The structure was solved with an automated centrosymmetric symbolic addition procedure on the Oxford KDF 9 computer. Refinement was performed using first isotropic and then anisotropic least-squares procedures, large-block 4

Bis-vinylogous Corrole: The First Expanded Corrole

“…X-ray analysis was performed on a single crystal of 5-Cl and allowed its unambiguous characterization. [12] Compound 5-Cl (Figure 2) exists as a fairly planar molecule with one pyrrole ring slightly out of the plane; a similar deviation from planarity of one pyrrole ring was also observed in the case of 3, [14] and the corresponding corrole monocation showed significant deviations from planarity. [15] This behavior was attributed to steric repulsion between the inner core hydrogen atoms; it is reasonable to attribute to a similar effect the deviation observed in the case of 5.…”

Coordination chemistry of corroles with focus on main group elements

“…Nobel laureate Dorothy C. Hodgkin, who focused on X-ray crystallography of Vitamin B 12 , was also the one who reported the first X-ray structural determination of a free-base (metal free) corrole [6]. Nevertheless, the chemistry of corroles remained largely undeveloped for decades because of severe synthetic obstacles.…”

High-valent corrole metal complexes

“…Corrole chemistry, which started in 1964 [2], also led to the ®rst structural characterization of a free-base corrole by Hodgkin and coworkers in 1971 in course of their Vitamin B 12 project [3]. The main research eorts during the years to come were devoted to the synthesis of corroles [4] and to investigation of the coordination chemistry of their metal complexes [5,6].…”