Transit ion

A. Abragam, B. Bicancy in Electron Paramagnetic Resonance of Transition Ions, Clarendon Press, Oxford 1970, p. 502. 

SDCI, gives an accurate representation of the molecular state. This is in contrast to single-reference singles-plus-doubles Cl (SDCI), which is often not very satisfactory for transit ion-metal diatomics, especially when the molecular state arises from a mixture of atomic states with different d occupations. 

Abragam, A., Bleaney, B. Electron Paramagnetic Resonance of Transition Ions. Dover, New York (1986)... 

Pilbrow, J.R. Transition Ion Electron Paramagnetic Resonance, Clarendon, Oxford (1990)... 

Optical Stability of Triorganostanny 1-Transit ion Metal Complexes [Methylphenyl(2-phenylpropyl)stannyl](triphenylphosphine)tricarbonyl cobalt (76)... 

The above historical outline refers mainly to the EPR of transition ions. Key events in the development of radical bioEPR were the synthesis and binding to biomolecules of stable spin labels in 1965 in Stanford (e.g., Griffith and McConnell 1966) and the discovery of spin traps in the second half of the 1960s by the groups of M. Iwamura and N. Inamoto in Tokyo A. Mackor et al. in Amsterdam and E. G. Janzen and B. J. Blackburn in Athens, Georgia (e.g., Janzen 1971), and their subsequent application in biological systems by J. R. Harbour and J. R. Bolton in London, Ontario (Harbour and Bolton 1975). 

Classes of metalloproteins. Transition ion prosthetic groups in proteins are... 

Biological metal transition ions and their nuclear spin... 

Some transition ions have central hyperfine splittings somewhat greater than this value, for example, for copper one typically finds Az values in the range 30-200 gauss, and so in these systems the perturbation is not so small, and one has to develop so-called second-order corrections to the analytical expression in Equation 5.12 or 5.13 that is valid only for very small perturbations. The second-order perturbation result (Hagen 1982a) for central hyperfine splitting is ... 

Most biochemically relevant high-spin systems have such short 7j-relaxation times that their EPR is broadened beyond detection at ambient temperatures. An exception is the class of S = 5/2 Mn" systems with D hx. Also, S = 7/2 Gd"1-based MRI shift reagents exhibit readily detectable room-temperature EPR spectra. Otherwise, aqueous-solution transition ion bioEPR is limited to complexes of S = 1/2 metals, in particular Cu", and to a lesser extent VIV02+, NiIn, Ni1, Mov, and Wv. Cupric is the stable oxidation state of biological copper under aerobic conditions, however, the other metals are stable as Vv, Ni", MoVI, and WVI, and, therefore, the other oxidation states associated with S = 1/2 paramagnetism may exhibit oxidative or reductive reactivity and may thus require specific experimental precautions such as strict anaerobicity over the course of the EPR experiment. 

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