10.1021/ja00247a009
The study explores the resonance Raman spectra of various metalloporphyrin derivatives, focusing on the correlation between core size and high-frequency skeletal mode frequencies. It was found that these correlations, which inversely relate core size to mode frequency, apply to Mn, Co, Zn, Fe, and Ni species, with slight revisions to previously determined coefficients. Deviations were noted for certain complexes, particularly low-valent five-coordinate adducts, which may be due to electronic effects such as porphyrin doming. The study also observed a core-size dependence for the "oxidation-state marker" v4, with low-valent Fe, Mn, and Co species showing negative deviations. Additionally, the research confirmed the core-size correlations for planar high-spin Fe" species and extended the analysis to metallo TPP's, noting differences in slopes and intercepts due to altered normal mode compositions. An unusual enhancement of anomalously polarized modes in ClMn"'TPP upon Soret band excitation was also reported, suggesting a mixing of charge transfer and T-T* transitions. The findings have implications for understanding the structural basis of heme proteins and their photoproducts.
10.1139/v80-010
The study investigates the preparation, characterization, and reactions of N-tert-butyldimethylsilyl derivatives of various heterocyclic compounds, including imidazole, 2-methylimidazole, 4-methylimidazole, benzimidazole, pyrazole, 1,2,4-triazole, and benzotriazole. These derivatives were synthesized using tert-butyldimethylsilyl chloride and the corresponding heterocyclic compounds. The products were identified and characterized using carbon and proton nuclear magnetic resonance (NMR), mass spectrometry, and elemental analysis. The study confirmed the absence of intermolecular silyl exchange at ambient temperature through carbon NMR spectra, but noted that such exchange occurred at elevated temperatures (130-160°C). The study also explored the reaction of these silyl derivatives with dimethylsulfoxide (DMSO), resulting in the formation of N-(methylthio)methyl derivatives of the heterocycles. The mechanism for this reaction involves a Pummerer rearrangement, and the products were characterized using various analytical techniques, providing insights into the stability and reactivity of these compounds under different conditions.
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