Magnetic circular dichroism spectra

Data on the protonation sites for a variety of azaindolizines have been summarized in the previous survey (76AHCS1, p. 536).Tlie measured magnetic circular dichroism spectra for 14 azaindolizines confirmed with some corrections the protonation sites of polyazaheterocycles previously reported and also established the conjugated acid structures of additional compounds (85JOC302).Tlie data are summarized in Scheme 1. 

The photochemical formation and the analysis of the absorption and magnetic circular dichro-ism spectra of the anion radical of zinc phthalocyanine were carried out. A complete assignment of the optical spectrum of the anion radical was proposed.834 Similarly, spectroelectrochemical cells have been used to record absorption and magnetic circular dichroism spectra of zinc phthalocyanines and a band assignment scheme proposed.835... 

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... 

Magnetic circular dichroism spectra of some 3-arylfervenulins and 3-aryltoxoflavins were studied (78JHC615). Hammett plots showed that substituents in both compounds exerted opposite effects on the magnetic CD spectra. The difference was explained by the contribution of the 1,5-dipolar structure of 3-aryltoxoflavins. 

Figure 9. Absorption and magnetic circular dichroism spectra of compounds 6(a) and 10(b) in THF-DE at 293 K. Optical path is 2mm. (Reproduced with permission from Ref. 15. Copyright 1985 North-Holland Physics Publishing Company.)...

Schreiner, A. F., Hauser, P. J. Magnetic circular dichroism spectra and electronic structures of tris(dialkyldithiocarbamato)chromium(lII) molecules, Cr(R2tc)s, and others. Inorg. Chem. II, 2706 (1972). 

CALCULATION OF MAGNETIC CIRCULAR DICHROISM SPECTRA WITH TIME-DEPENDENT DENSITY FUNCTIONAL THEORY... 

The UV and magnetic circular dichroism spectra of mesoionic pyrido[2,l-b][l,3]oxazine (16, R = CH2Ph) were measured in acetonitrile (85JOC5050). UV spectra of hexahydro[l,3]oxazino[3,2-a]isoquinolines (17) indicated that the ring form (17R) was present in cyclohexane... 

Fig. 7. Optical absorption and magnetic circular dichroism spectra of oxidized hydrogenase from M. thermoautotrophicum (AH strain), nickel concentration 120 pM. (a) Optical absorption spectrum, at room temperature the absorption is predominantly due to iron-sulfur clusters, (b) MCD spectra recorded at 1.53, 4.22, and 8.9 K, in a magnetic field of 4.5 T MCD is predominantly due to Ni(III), which is the only paramagnetic species in the oxidized enzyme. Reproduced, with permission, from Ref. 57.

Fig. 6. Absorption and magnetic circular dichroism spectra of Co2+ thermolysin. (A) MCD spectra. (B) Absorption spectra.

Fig. 8. Magnetic circular dichroism spectra of Co2+ complexes. The oxygen and nitrogen ligands are given for each complex.

An Fe(II) complex with a tethered axial thiolate has also been prepared (12.29) as the CO adduct. This complex exhibits UV-visible and magnetic circular dichroism spectra similar to the analogous CO complexes of the iron P-450 family. 

Table IV. Magnetic Circular Dichroism Spectra of Intermediates I-V...

The near IR and magnetic circular dichroism spectra of [(NH3)5Os(4,4 -bipy)Os(NH3)5]6+ have... 

The best characterized species is [Os2(N2)(NH3)10]5+ made as a bromide or as a tosylate from reaction of [0s(H20)(NH3)s]3+ with [Os(N2)(NH3)5]2+ in the presence of zinc amalgam. The stability of the mixed valence system (formally Os111 11) has been ascribed to electronic delocalization effects and an MO scheme proposed,2 0s but it is not clear why it appears to be more stable than its reduction product, [Os(N2)(NH3),0]4+. Magnetic circular dichroism spectra and cyclic voltammetry of the ion have been measured.28011 A number of other mixed homonuclear species are known, viz. [0s2(N2)(NH3)9(H20)]s+, [Os2(N2)(NH3)9C1]4+, [Os2(N2)(NH3)8C12]3+ and... 

In order to understand the charge transfer features of the Blue Copper site, the variable-temperature optical absorption, room-temperature circular dichroism, and magnetic circular dichroism spectra of plastocyanin, stellacyanin, and azurin were studied355. As can be seen for plastocyanin in Fig. 12, the relative intensities (and signs, in the case of CD and MCD) of these transitions vary among the different types of spectra. This is a result of the difference in selection rules for absorption, CD, and MCD spectra, as mentioned in the Introduction. A careful comparison of the three types of spectra and the absorption bandshape temperature dependence (see moment analysis in Ref. 35, pp. 176-177)... 

The molybdenum analog of chromocene see Metallocene Complexes) [CP2M0] (molybdenocene) is not stable and has only been isolated using matrix isolation techniques see Matrix Isolation). The IR, magnetic circular dichroism spectra of the matrix isolated [CP2M0] were interpreted in terms of a paramagnetic metallocene, with parallel rings. 

The spin Hamiltonian formalism, which is also needed to interpret, for example, electron paramagnetic resonance or magnetic circular dichroism spectra see Magnetic Circular Dichroism (MCD) Spectroscopy), was first applied to the interpretation of magnetic Mossbauer spectra by Wickmann, Klein and Shirley and was implemented into a computer program by Miinck et al. in the early 1970s. For most studies of mononuclear iron centers with electron spin quantum number S, the following electronic Hamiltonian is used ... 

Calculation of Magnetic Circular Dichroism Spectra With Time-Dependent Density Functional Theory Michael Seth and Tom Ziegler... 

Iron-porphyrins, synthesis and coordination properties of 86PAC1493. Magnetic circular dichroism spectra of -substituted porphyrins 88-ACR95. 

The effects of the role of matrix birefringence, photoselection, and rotational diffusion on measuring the circular dichroism of chiral excited triplets embedded in a rigid matrix have been examined. The techniques described in this paper are applied to chiral dimer-like molecules in the binaphthyl and spirobifluorene series. Natural and magnetic circular dichroism spectra of selenofenchone provide evidence for a singlet-triplet component of the n - IT transition. ... 

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

Davydov, R.M., S.N. Magonov, A.M. Arutyunyan, and Y.A. Sharonov (1978). Absorption and magnetic circular dichroism spectra of heme-containing proteins in nonequilibrium states. IV Cytochrome c and its derivatives. Molek. Biol. (Eng. Transl.) 12, 1037-1042. 

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