107374-49-2Relevant academic research and scientific papers
Resonance Raman spectroscopic detection of steric-induced distortions of axial ligand binding for dioxygen adducts of superstructured cobalt-porphyrin complexes
Proniewicz, Leonard M.,Bruha, Alan,Nakamoto, Kazuo,Uemori, Yoshio,Kyuno, Eishin,Kincaid, James R.
, p. 9100 - 9104 (2007/10/02)
Resonance Raman studies are carried out for the O2 adducts of superstructured "jellyfish" cobalt-porphyrin complexes with several trans-axial ligands, namely, pyridine, 3,5-lutidine, and imidazole as well as several of their deuteriated analogues. Two superstructured, bis-strapped porphyrins, having either short (9 carbon atoms) or long (12 carbon atoms) strap lengths, are employed along with sterically relaxed (non-strapped) porphyrins. It is found that the short-strap derivative induces distortion of the bound ligands while the long-strap analogue permits normal, unencumbered binding. While the distortion of the trans-axial ligand does not significantly affect the Co-O2 linkage, as judged by the constancy of the inherent frequency of ν(O-O), significant shifts of the ligand internal modes give rise to substantially altered spectra as a result of variations in the strength of vibrational coupling of the ν(O-O) with internal modes of the trans-axial ligand.
Regulated dioxygen affinities by steric restrictions on axial bases in jellyfish type cobalt(II) porphyrins
Uemori, Yoshio,Miyakawa, Hiromasa,Kyuno, Eishin
, p. 377 - 382 (2008/10/08)
The title compounds were prepared to examine the effect of axial base orientation on the dioxygen affinities of (porphyrinato)-cobalt(II) complexes. These porphyrins were derived from meso-tetrakis(2-aminophenyl)porphyrin, with valeramido or pivalamido groups appended on one side of the porphyrin plane as fences in order to control the orientation of the axial base plane, while a nonanediamido or dodecanediamido group is bridged over the other side of the porphyrin plane to inhibit the binding of axial bases. Equilibrium constants in toluene solution are reported for bindings of imidazoles, pyridine, and O2 to the cobalt(II) complexes of these porphyrins. As the steric bulk of the fences increases, the bindings of axial bases are enhanced, while the dioxygen affinities are decreased. These changes in dioxygen affinities are interpreted in terms of the orientation of the axial base plane, which changes the strength of π-electron donation from the axial base to the (porphyrinato)cobalt(II).
