Corrphycene: A New Porphyrin Isomer

Abstract

COMMUNICATIONS [7] Crystal structure analyses. colorless crystals of 3a and 15 were investieated on a lour-circle diffractometcr (CAD4, at -80 'c' with Cu,, radiation ( 2 =154.178 pm). 3a: C,,H,,B,Li,SiZ.2THF. crystal dimensions 0 6 x 0.3 x 0.2 inm'. monoclinic. space group P2,c. Z = 4. (I = 9 7 2 3 2 ) . h = 1173.5(2). <' = 2890.7(6) pm. / I = 98.45(3) . Vr7 = 3262.1 x lO-"m', pca,Ld = 0.99X gcm -'; 3994 measured reflections in the range up to 20 = 110 (w scans). 3903 of which \+ere independent and were used for the further calculati~ns alter Loreiitz and polarization correction: no absorpt~on correction 111 = I 1 Ocm-') The structure was solved by direct methods and refined against the ti: data xith full matrix. A disorder showing up in the differenceFourlei-5yntheses was accounted for bq a "split atom model" where a C 5 -SiMe, group superposes the B3-iBu unit at 8 3 and. vice versa. a B3-/Bu group superposes the C5-SiMe3 unit at C 5 . Due to these superpositions. geometrrc restraints olihe B C (160 pm) and Si-C (187 pm) bond length wcrc used during refinement. and the temperature factors of atoms approaching each other were defined to be equal. In this way good conbergence and a maximal residual electron density 0.35 e k ' were achieved. The distribution of the alternative arrangements of the molecules was determincd to be 59.3(4) aiid 40.7%). The H a t o m u'ere localized iii part by dillerence Fourier syntheses: the others were calculated; they were included in the calculation riding on their bonding partners and with isotropic temperature factors coinmon by gsoups. Anisotropic teinpcratui-e factors %ese used foi-all the remaining atom& except C 7 . wRi = 0.2066 (SHELX 93 program). corresponding to R = 0.069 for 2951 reflections with &>4u(F,>). inanimal residual electron density 0.33 e k ' . -15: C,,H,,B,Si,, crystal dimcnsions 0.7 x 0.3 x 0.2 n1m3, monoclinic. space group P2,:n. Z = 4. ci = 928.9(2). h = 1655,2(3). c = 2154.4(4) pin. /) = 92.80(3) , VF7 = 3308.5 x I O -" in'. pc,,L6 = 1.009 gcni-'; 4461 reflections iii the range up to 211 =110 ( ( , I scans), 4157 of wliicli were independent 41 54 reflections \+ere used foi-further calculations after Lorentr aiid polarizatioii correction. the structure solutioii and refinement a s for 3 a led to wR,=0.1955, corresponding to R = 0.064 for 2123 reflections uith ti) > 40(&,). and ;I maximal residual electron densit) of 0 34 e k ' . Further details of the crystal structure investigations inay be obtained from the Fachiiiformationsreiitrum Karlsruhe. D-76344 Eegenstein-Leopoldslitifeii (FRG). on quoting the depository number CSD-58435.

Functional Analysis of the Iron(II) Etiocorrphycene Incorporated in the Myoglobin Heme Pocket.

“…The metallo cavity is trapezoidal in corrphycene, 2) in remarkable contrast with the square cavity in porphyrin. The deformed equatorial ligand field could cause unfavorable overlap of the electron lobes of the four pyrrole-nitrogens with the iron d x 2 -y 2 orbital.…”

“…Corrphycene is a novel structural isomer of porphyrin synthesized by Sessler et al in 1994. 2) The macrocycle is formally derived from porphyrin by removing one meso-carbon to the diagonal bridge. The structural change deforms the square metallo cavity of porphyrin into a trapezoid, although the resultant corrphycene remains flat and aromatic like the parent porphyrin.…”

Corrole isomers: intrinsic gas-phase shapes via traveling wave ion mobility mass spectrometry and dissociation chemistries via tandem mass spectrometry

“…The resolving power (R p ) of the technique is dependent on single-peak resolution parameters, i.e. the ratio between the drift time (dt) and the peak width at half height (w 1/2 ), according to eqn (2).…”

“…Characterization, identification and the measurement of the distinctive physico-chemical properties of isomeric molecules are therefore a subject of fundamental importance in chemistry. For porphyrins, a multitude of isomers with peculiar properties have been generated by changing the number of carbon atoms between pyrrole rings such as in porphycenes, 1 porphycerins, 2,3 hemiporphycenes, 4 and isoporphycenes 5 (Scheme 1). Exceptional examples of porphyrin isomers are Scheme derived from "confusion" and "neo-confusion", where the new structures are generated by changing the position of the nitrogen atom.…”

Light-Induced Tautomerization in Porphyrin Isomers

“…Finally, it has yet to be determined whether the movement of the two protons in the excited state occurs in an asynchronous or a stepwise fashion. Recent syntheses of structural isomers of porphyrin -porphycene (2) [44], corrphycene (3) [45] and hemiporphycene (4) [46] (Fig. 1) may turn out to be of great help in the study of tautomerization mechanisms.…”