Organometallic compounds, paramagnetic

The usual carbon-) 3 chemical shift range of organic compounds ( 250 ppm) considerably expands in organometallic compounds. Paramagnetic metals in metallocenes (Table 4.72) induce particularly large 13C shift values [476]. 

Harada A (1994) Stereochemistry of Organometallic and Inorganic Compounds, Vol 5, Chains, Clusters, Inclusion Compounds, Paramagnetic Labels, and Organic Rings. Zanello P (ed), Elsevier, Amsterdam, p 409... 

Chemical shifts have been reported for [Me3CCH2HgX] 203) (see Table XII), tr-allylic derivatives (see Table XIII), o-cyclopentadienyl derivatives (see Table XIV), and miscellaneous compounds (see Table XV). In the case of fluxional a-cyclopentadienyl derivatives, it has been shown that chemical shifts can be used to differentiate between fluxional o-cyclopentadienyl derivatives and w-cyclopentadienyl derivatives 103). The NMR spectrum of [Sb(cyclopropyl)s] has only two carbon resonances, showing that the molecule is fluxional (56) and the NMR spectrum of the naturally occurring organometallic compound, 5 -deoxyadenosylcobalamin, has been reported (65). For a number of norbornane and allylic derivatives of palladium and platinum, a number of linear relationships have been found between chemical shifts of various carbon atoms. It was suggested that a term due to paramagnetic shielding by the metal was dominant 52b). 

Bonding Energetics of Organometallic Compounds Electron Transfer in Coordination Compounds Paramagnetic Organometallic Complexes Structure Property Maps for Inorganic Solids. 

Complexes containing vanadium in low oxidation states, apart from organometallic compounds, are known with ligands such as bipy, phen, nitric oxide, and tertiary phosphines, which stabihze such oxidation states. Depending on their electronic structure, V and V complexes may be diamagnetic, which permits study by NMR spectroscopy, and EPR spectroscopy has been used to study paramagnetic V complexes. 

A wide variety of paramagnetic organometallic compounds are known. The large majority of these are classified as metallocenes and are of considerable NMR interest. In studying such systems Kohler (179) has suggested that spectroscopy offers distinct advantages over spectroscopy. From studies on bis-(h -t-butyl-... 

The rate of intersystem crossing can be increased by the presence of paramagnetic molecules such as oxygen as well as by molecules with heavy atoms such as halogen or organometallic compounds. These are concentration-dependent effects. In the case of oxygen the rate constant of a radiationless singlet-triplet transition can be written as... 

Current subject areas covered are Amino Acids, Peptides and Proteins, Carbohydrate Chemistry, Catalysis, Chemical Modelling Applications and Theory, Electron Paramagnetic Resonance, Nuclear Magnetic Resonance, Organometallic Chemistry, Organophosphorus Chemistry, Photochemistry and Spectroscopic Properties of Inorganic and Organometallic Compounds. 

Stable paramagnetic organometallic compounds are exceedingly rare and so the few that are known have been studied in detail. ESR has shown (455) that in (7T-C5H5)jNi3(CO)2, which has the structure shown in Fig. 52, this molecule has symmetry and the unpaired electron is in the A 7T-bonding molecular orbital linking the three nickel atoms... 

Electron Paramagnetic Resonance Vol. 16 II Nuclear Magnetic Resonance Vol. 27, 28 Organometallic Chemistry Vol. 26,27 Organophosphorus Chemistry Vol. 29 fi Photochemistry Vol 29,30 Spectroscopic Properties of Inorganic and Organometallic Compounds Vol. 31,32... 

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