33058-44-5

Upstream product

• 17632-19-8 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine cobalt(II) 
• 1923-70-2 tetrabutylammonium perchlorate 

Relevant academic research and scientific papers

Vibrational, Electronic, and Structural Properties of Cobalt, Copper, and Zinc Octaethylporphyrin ? Cation Radicals

Optical and resonance Raman (RR) spectroscopic characterization of the oxidation products of several metallooctaethylporphyrins has been carried out.One-electron oxidation of the macrocycle yields a series of divalent metal substituted octaethylporphyrin ? cation radicals, MIIOEP.+ClO4- (M = Ni, Co, Cu, and Zn).The porphyrin core vibrational frequencies above 1450 cm-1 of these complexes are described by a linear function of center to pyrrole nitrogen distances.A comparison of these structural correlations and of Raman depolarization ratios with those of the parent MOEP compounds is used to established vibrational mode assignments for the cations.The agreement between the correlation parameters of the MOEP and MOEP.+ClO4- suggests similar potential energy distributions in the normal modes of both species.We find that the frequencies of the stretching modes with dominantly CbCb character increase, whereas those with CaCm and CaN character decrease in the cation radical relative to the neutral metalloporphyrin.Similar trends in Soret band maxima for the ? cation radicals and their parent compounds reflect changes in the relative energy of the a2u(?) orbital.These structural correlations seem to be essentially insensitive to 2A2u vs 2A1u radical designation.With the vibrational mode correlations as a guide to evaluation of porphyrin core geometry, we have carried out a detailed analysis of the oxidation products of CoIIOEP and we suggest structures for the two-electron-oxidized species CoIIIOEP.+2ClO4- and CoIIIOEP.+2Br-.Differences in the high-frequency vibrations of these two compounds are interpreted in terms of expansion or possible ruffling of the porphyrrin core in the latter relative to the former compound.RR excitation in the 600-680-nm region of the CoIIIOEP.+2Br- absorptions shows a lack of anomalously polarized scattering and produces spectra similar to those obtained with near-UV excitation.This suggests the absence of strong Herzberg-Teller coupling between the excited electronic states of this ? cation radical.

Resonance Raman Spectra of Metalloctaethylporphyrin Cation Radicals with a1u and a2u Orbital Character

Resonance Raman (RR) spectra are reported for radical cations of MIIOEP (OEP = octaethylporphyrin; M = Zn, Mg, Ni, Cu) and for the perchlorate and bromide salts of IIIOEP>+, produced by electrochemical and/or chemical oxidation.The enhancement patterns obtained with B (4067 angstroem) band excitation (except M = Zn and Mg, for which fluorescence overwhelms the Q band RR spectra) permitted assignment of most of the porphyrin skeletal models above 1000 cm-1, and frequency shifts relative to the unoxidized porphyrins have been cataloged.Those radicals, magnesium(II), zink(II), and cobalt(III) bromides, whose EPR spectra, have beenassigned on the basis of electron removal from an a1u molecular oribtal show a cammon pattern of shifts, while those with a2u-type EPR spectra, nickel(II), and cobalt(III) perchlorates, show a different pattern.The CuII radical, whose visible absorption spectrum resebles that of other a2u radicals, likewise has an a2u RR frequency shift pattern.The largest shifts are showen by the most prominent RR bands in the B-band-excited spectra, v4 (CaN breathing, primarily) and v2 (CbCb breathing, primarily).These shift up (+14 to +21 cm-1) and down (-19 to -38 cm-1), respectively, for the a1u radicals, but down (-12 to -22 cm-1) and up (+20 to +23 cm-1) for the a2u radicals.Thus an identification of the radical type is quite straighforvard in B-band-excited RR spectra.The directions of the shifts, however, are opposite to those expected from simple orbital simmetry arguments, since the a2u molecular orbital is bonding with respect to the Cb-Cb bonds and antibonding with respect to the Ca-N bonds, and vive versa for the a1u orbital.This discrepancy invites further examination via vibrational and electronic calculations.