Structural heterogeneity and coordination chemistry of nickel(II) octaethyl-meso-nitroporphyrins

Journal Article · Wed Apr 20 00:00:00 EDT 1994 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00087a011· OSTI ID:7166016

Hobbs, J D ^[1]; Majumder, S A; Shelnutt, J A ^[2]; Luo, L; Sickelsmith, G A; Quirke, J M.E. ^[3]; Medforth, C J; Smith, K M ^[4]

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1. Sandia National Lab., Albuquerque, NM (United States)
2. Sandia National Lab., Albuquerque, NM (United States) Univ. of New Mexico, Albuquerque, NM (United States)
3. Florida International Univ., Miami, FL (United States)
4. Univ. of California, Davis, CA (United States)

The role of steric crowding of peripheral substituents in causing nonplanar distortions of the porphyrin macrocycle has been investigated in a series of nickel(II) meso-nitrooctaethylporphyrins as models for protein-induced nonplanar distortions of metal-tetrapyrrole cofactors. UV-visible absorption spectra, resonance Raman spectra, nuclear magnetic resonance spectra, and molecular mechanics calculations are given for nickel(II) derivatives of 5-mono-, 5,15-di-, 5,10-di-, 5,10,15-tri-, and 5,10,15,20-meso-nitro-substituted octaethylprophyrins. The frequencies of the structure-sensitive Raman lines are found to shift to lower energies in response to sterically induced nonplanar distortion of the porphyrin macrocycle rather than in response to the addition of a strong electron-withdrawing nitro substituent. The Raman spectra of all except tetranitrooctaethylporphyrin show spectroscopic evidence of heterogeneity resulting from the presence of conformers with differing degrees of nonplanarity. Evidence from UV-visible absorption spectra, nuclear magnetic resonance spectra, and molecular mechanics calculations suggests that nickel tetranitrooctaethylporphyrin in solution may exhibit conformers with different types of nonplanar distortions which however do not differ in the relative degree of distortion. 44 refs., 9 figs., 3 tabs.

• DOE Contract Number: AC04-94AL85000
• OSTI ID: 7166016
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 116:8; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NICKEL COMPLEXES
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
RAMAN SPECTRA
STEREOCHEMISTRY
COMPILED DATA
PORPHYRINS
CARBOXYLIC ACIDS
COMPLEXES
DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RESONANCE
SPECTRA
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures