Nature of the visible absorption bands in metal-amine solutions

1969 ◽  
Vol 73 (9) ◽  
pp. 3098-3101 ◽  
Author(s):  
S. Matalon ◽  
S. Golden ◽  
M. Ottolenghi
Keyword(s):  
Absorption Bands ◽  
Visible Absorption ◽  
Metal Amine ◽  
Amine Solutions

Meso-aryl-ß-pyrrolic positions interactions in meso-tetraarylporphyrins: Flat arylporphyrins and building blocks for oligoporphyrins

2004 ◽  
Vol 08 (02) ◽  
pp. 111-119 ◽  
Author(s):  
Henry J. Callot ◽  
Romain Ruppert ◽  
Christophe Jeandon ◽  
Sébastien Richeter
Keyword(s):  
Building Blocks ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Aryl Ring ◽  
Porphyrin Macrocycle ◽  
Uv Visible

Aryl groups bound to the meso positions of porphyrins often react with neighboring groups, in particular ß-acyl groups to give highly diversified monomeric and dimeric new functionalized porphyrins. The products, whose meso-aryl ring approaches coplanarity with the porphyrin macrocycle, show large shifts of UV-visible absorption bands and various potentialities for building external chelating moieties and assembling oligoporphyrins.

Initial Reaction Intermediates in the Oxidation of Ascorbic Acid by Nitrous Acid

1981 ◽  
Vol 44 (1) ◽  
pp. 28-32 ◽  
Author(s):  
JAY B. FOX ◽  
ROSEMARY N. FIDDLER ◽  
AARON E. WASSERMAN
Keyword(s):  
Nitric Oxide ◽  
Ascorbic Acid ◽  
Nitrous Acid ◽  
Organic Radicals ◽  
Initial Reaction ◽  
Reaction Intermediates ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Decomposition Products

Nitrite and ascorbate react to form nitric oxide at pH 5.5. In the initial stages of the reaction, seven intermediates can be identified spectrally and chromatographically; these include two colorless nitroso derivatives which contain 30–60% of the initial nitrite, two nitroso reductant derivatives absorbing at 345 and 412 nm, diketogulonic acid and two further decomposition products. None of the intermediates was paramagnetic; except for diketogulonic acid, all decomposed rapidly during or after isolation. Based on the order of appearance of the ultraviolet and visible absorption bands in the reaction mixtures, the observed characteristics of the intermediates, and the lack of organic radicals, a sequence is proposed for the initial steps in the oxidation of ascorbic acid by nitrous acid.

Species Present in Alkali‐Metal Amine Solutions

1964 ◽  
Vol 40 (12) ◽  
pp. 3729-3730 ◽  
Author(s):  
Michael Ottolenghi ◽  
Kedma Bar‐Eli ◽  
Henry Linschitz ◽  
T. R. Tuttle
Keyword(s):  
Alkali Metal ◽  
Metal Amine ◽  
Amine Solutions

A spectroscopic study of the solvent dependent processes of the anils of benzaldehyde and salicylaldehyde

1982 ◽  
Vol 60 (13) ◽  
pp. 1727-1737 ◽  
Author(s):  
Jerry W. Lewis ◽  
Camille Sandorfy
Keyword(s):  
Hydrogen Bond ◽  
Ground State ◽  
Spectral Characteristics ◽  
Infrared And Raman Spectra ◽  
Absorption Data ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Raman Spectral ◽  
Dependent Processes ◽  
Electronic Ground

The ultraviolet–visible, infrared, and Raman spectral characteristics of some anils of benzaldehyde and salicylaldehyde in several solvents have been investigated. The ultraviolet–visible absorption data indicate that in solvents with a proton donating ability less than or equal to trifluoroethanol a single equilibrium exists in solutions of N-(2-hydroxybenzylidene)aniline, whereas in solvents with a proton donating ability equal to or greater than hexafluoroisopropanol more than one equilibrium occurs. The infrared spectra of this compound dissolved in trifluoroethanol do not show new absorption bands in the 1700–1500 cm−1 region; however, new absorption bands in this region do appear when hexafluoroisopropanol is employed as solvent. From these data it is inferred that the first equilibrium involves the breaking of the chelate hydrogen bond and the second equilibrium involves actual protonation of N-(2-hydroxybenzylidene)aniline in the electronic ground state. A comparison of the infrared and Raman spectra of the title compounds is also made and alternate assignments for several observed bands in the 1700–1500 cm−1 region are proposed.

Spectroelectrochemical Study of some μ3-Oxo-μ-acetato Trinuclear Rhodium(III) and Iridium(III) Complexes

1995 ◽  
Vol 50 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Kenta Takahashi ◽  
Keisuke Umakoshi ◽  
Akihiro Kikuchi ◽  
Yoichi Sasaki ◽  
Masato Tominaga ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Electronic Absorption Spectrum ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Visible Region ◽  
Absorption Bands ◽  
Visible Absorption ◽  
The One ◽  
Species Being

New trinuclear rhodium(III) complexes, [Rh3(μ3-O)(μ-CH3COO)6(L)3]+ (L = imidazole (Him), 1-methylimidazole (Meim), and 4-methylpyridine (Mepy)) have been prepared. The Him, Meim, and Mepy complexes show reversible one-electron oxidation waves at E1/2 = +1.12, +1.12, and +1.28 V vs Ag/AgCl, respectively, in acetonitrile. Electronic absorption spectra of the one electron oxidized species of these complexes and [Rh3(μ3-O)(μ-CH3COO)6(py)3]+ (py = pyridine) (E1/2 = +1.32 V ) were obtained by spectroelectrochemical techniques. While the Rh3(III,III,III) states show no strong visible absorption, the Rh3(III,III,IV ) species give a band at ca. 700 nm (ε = 3390-5540 mol dm-3 cm-1). [Ir3(μ3-O)(μ-CH3COO)6(py)3]+ with no strong absorption in the visible region, shows two reversible one-electron oxidation waves at +0.68 and +1.86 V in acetonitrile. The electronic absorption spectrum of the one-electron oxidized species (Ir3(III,III,IV )) also shows some absorption bands (688 nm (ε, 5119), 1093 (2325) and 1400 (ca. 1800)). It is suggested that the oxidation removes an electron from the fully occupied anti-bonding orbital based on metal-dπ-μ3-O-pπ interactions, the absorption bands of the (III,III,IV ) species being assigned to transitions to the anti-bonding orbital.

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