Transition metal paramagnetic

TTF CH=CH py)2] (PF6)- 2CH2C12 was the first radical cation salt of a paramagnetic transition metal complex containing TTF CH=CH py as ligand. 

Because of the l/r dependence, the exchange interaction rapidly decreases with an increase in the difference between the principal quantum numbers of the impaired electrons and the core vacancy. Thus multiplet splitting is negligible in the Is spectra of paramagnetic transition metal compounds. On the other hand, shake-up intensity is essentially independent of the core level involved. Hence one can distinguish between shake-up and multiplet satellites by changing the principal quantum number of the core electron ionized76. ... 

Electron nuclear double resonance (ENDOR) and electron spin-echo envelope modulation (ESEEM) are two of a variety of pulsed EPR techniques that are used to study paramagnetic metal centers in metalloenzymes. The techniques are discussed in Chapter 4 of reference la and will not be discussed in any detail here. The techniques can define electron-nuclear hyperfine interactions too small to be resolved within the natural width of the EPR line. For instance, as a paramagnetic transition metal center in a metalloprotein interacts with magnetic nuclei such as H, H, P, or these... 

Use of EPR Spectroscopy in Elucidating Electronic Structures of Paramagnetic Transition Metal Complexes 70... 

The technique of electron-spin resonance (e.s.r.), well known as an important tool for studying the structure of paramagnetic transition-metal complexes, has recently been used in the detection and study of a wide range of organic radicals, both stable and unstable, in fluids and solids. 

A review of all of the different types of EPR spectrum that can be obtained from the various paramagnetic transition metal ions is beyond the scope of this chapter. However, a few examples will be presented below to illustrate the type of information that can be obtained. 

Fig. 5 Generation of valence tautomeric ligand-centered radicals from paramagnetic transition metal complexes...

Paramagnetic transition metal ions partially exchanged into... 

A second way to overcome this spin conservation obstacle is via reaction of 302 with a paramagnetic (transition) metal ion, affording a superoxometal complex (Fig. 4.1, Reaction (3)). Subsequent inter- or intramolecular electron-transfer processes can lead to the formation of a variety of metal-oxygen species (Fig. 4.2) which may play a role in the oxidation of organic substrates. 

TABLE XVIII The Chemical Shifts of Some Paramagnetic Transition Metal Complexes ... 

What is this paramagnetic transition metal oxidation and spin state ... 

Contact, or through-bond, shifts occur if there is a finite probability of finding the unpaired electron of the metal at the nucleus of interest. Predicting the direction and magnitude of contact shifts requires molecular orbital calculations. Contact shifts are significant in covalently bonded metal systems and are pronounced for paramagnetic transition metal complexes such as Ni(acac)2 and Co(acac)2. Contact shifts extend over 7T-electron systems, and are particularly large with Co(acac)2 since the Co(II) has an unpaired electron in a d-orbital that can jr-bond with certain substrates. ... 

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