Magnetic circular dichroism determination

The redox potentials of zinc-substituted phthalocyanines are shown to be linearly dependent on the total Hammett substituent constant.837 In 1987, Stillman and co-workers used the absorption and magnetic circular dichroism spectra of the zinc phthalocyanine and its 7r-cation-radical species to assign the observed bands on the basis of theoretical calculations. The neutral and oxidized zinc phthalocyanine complexes with cyanide, imidazole, and pyridine were used with the key factor in these studies the stability of the 7r-cation-radical species.838 The structure of zinc chloro(phthalocyaninato) has been determined and conductivity investigated.839... 

In connection with certain forms of spectroscopy (e.g., circular dichroism and magnetic circular dichroism) it is necessary to know what electronic transitions are magnetic dipole allowed. The operators for this have the symmetry properties of r, and Rz. For a molecule of Tlt symmetry, determine what pairs of states could be connected by a magnetic dipole allowed transition. 

Measurements. The absorption, circular dichroism (CD), and ESR spectra were recorded with a Hitachi 323 spectrophotometer, a JASCO MOE-1 magnetic circular dichroism spectrometer, and a JEOL JES-FE3X ESR spectrometer, respectively. The measurements of the spectra were carried out at 15°-20°C except for the ESR spectra, which were recorded at 77 K. The resonance Raman spectra were recorded at 10°C with 488.0-nm excitation (Ar+ laser) on a JEOL JRS-400D-002 spectrophotometer. The concentration of copper was determined to be 4.9mM by atomic absorption measured by a Nippon Jarrell-Ash AA-1 spectrometer. 

X-Band ESR spectra were obtained at 77 and 293 K with a JES-FE-3X spectrometer. The g-values were determined relative to Li-TCNQ(g = 2.0026) and the magnetic fields were calibrated by the splitting of Mn(II) in MgO(AH3 4 = 86.9 G). Magnetic circular dichroism (MCD) measurements, using a 11.7-kG magnet, were carried out on a Jasco J-20 spectro-polarimeter and are expressed in terms of molecular ellipticity, [0] = 2.303 (4500/7r) ( - r), with units of (deg cm2)/d mol. 

The structure of Te4 has been determined (102) from the crystal structures of Te4(AlCl4)a and Te4(AlaCl7)2. In both cases the Te4 ion lies on a center of symmetry and is almost exactly square planar. The tellurium-tellurium distance of 2.66 A is significantly shorter than the tellurium-tellurium distance of 2.864 A within the spiral chain in elemental tellurium (105). This is consistent with a structure exactly analogous to that for 804 + in which each bond has 25% double bond character. The Raman spectra of Te4 in solution and the solid state are analogous to those of 804 and 84 but shifted to lower frequency (Table VIII). The magnetic circular dichroism (75) and visible and... 

Ionization constants of hydroxy- and mercaptopyridazines, ° of amino- and diaminopyridazines and their quaternization products,of methylsulfinylpyridazines," and of pyridazinium ylides have been recorded. The basicities of a series of pyridazines have been determined and correlated with substituent constants using the Hammett free-energy relationship. The magnetic susceptibility of pyridazine was measured, and the rate constant for the reaction of hydrogen atoms with pyridazine was determined. The experimental dipole moment, Kerr constant, and molar Cotton-Mouton constant, obtained at 298 K and 633 nm, are reported. The magnetic circular dichroism spectrum of pyridazine has been measured. ... 

Table I. Electronic substituted constants determined from magnetic circular dichroism spectra of simple substituted benzene derivatives 1A1g+1B2u transition.

There are some reports on the protonation sites of some of these systems. Proton NMR, in combination with C and N NMR data, has been used to determine the protonation sites of (64), (65), and (67) as occurring at N-1 (see Section 8.12.3.1.1) <91MI 812-02,91MRC468>. Using magnetic circular dichroism studies (see Section 8.12.3.5), the protonation of (64) was found to occur either at N-1 or N-4, whereas for (65), protonation at the 1-position was the only choice consistent with the calculations <85JOC302>. 

Magnetic circular dichroism (MCD) was used to determine the conformation and the dihedral angles of bipyridyls (84BCSJ341). 

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