Nuclear magnetic resonance transition metal complexes

In the last few years, DFT has also become one of the prime methods for the study of nuclear magnetic resonance (NMR) chemical shifts in transition metal complexes and other large molecules. DFT calculations of NMR chemical shifts have been reviewed (3,4). 

Included for the first time in this section are books and surveys on spectroscopic techniques which are of great use to the organometallic chemist. In addition to the Chemical Society Specialist Periodical Reports on Spectroscopic Properties of Inorganic and Organometallic Compounds (B6.1) and Mass Spectrometry (B6.2), a series of Annual Reviews (volumes 1 or 2) or Reports (volume 3 onwards) on Nuclear Magnetic Resonance Spectroscopy contains surveys of or P NMR results appertaining to organo-transition metal complexes. 

R. Fields Fluorine-19 Nuclear Magnetic Resonance Spectroscopy, pp. 99-304 (513), esp. pp. 255 -286, Transition metal complexes of fluorinated molecules. 

Solid-state nuclear magnetic resonance (NMR) has been extensively used to assess structural properties, electronic parameters and diffusion behavior of the hydride phases of numerous metals and alloys using mostly transient NMR techniques or low-resolution spectroscopy [3]. The NMR relaxation times are extremely useful to assess various diffusion processes over very wide ranges of hydrogen mobility in crystalline and amorphous phases [3]. In addition, several borohydrides [4-6] and alanates [7-11] have also been characterized by these conventional solid-state NMR methods over the years where most attention was on rotation dynamics of the BHT, A1H4, and AlHe anions detection of order-disorder phase transitions or thermal decomposition. There has been little indication of fast long-range diffusion behavior in any complex hydride studied by NMR to date [4-11]. 

Use. The oligomerization of olefins has generally been carried out with zero-valent transition metal complexes (mononuclear catalysts) and usually leads to an array of dienes see 1, 259). Schrauzer et at.1 of the Shell Development Co. reasoned that a dinuclear catalyst such as ZnfCo(CO).,J2 in which the two cobalt centers are connected close to each other will lead to new transition state formation from which different products can form. As a model, they examined the dimerization of nor-hornadiene and with the new catalyst obtained in almost quantitative yield a single dimer, m.p. 65-65.6°, shown unequivocably by elemental analysis (C14H16), infrared, nuclear magnetic resonance, and mass spectrometry to have the structure (2). 

Fluorophosphines are tervalent phosphorus compounds containing phosphorus-fluorine bonds and they often show markedly different chemical behavior compared with other halogenophosphines. This article is mainly concerned with recent advances in the chemistry of derivatives of PF 3 of the type PF3 X , with particular reference to (a) synthesis of new structural types, (6) the role of fluorophosphines as ligands, particularly in transition metal complexes, and (c) nuclear magnetic resonance (NMR) studies. 

The most common and important complex ions are hydrated metal ions. The coordination numbers and structures of some of these simple complexes have been determined. Isotope dilution techniques were used to show that Cr and Al are bonded rather firmly to six water molecules in aqueous solutions. The interpretation of the visible spectra of solutions of transition metal ions using CFT indicates that ions such as Mn, Fe, Co, Ni, Cr, and Fe are octahedral [M(H20)6] species. For non-transition metal ions it has been more difficult to obtain structural information. Flowever, nuclear magnetic resonance spectroscopy demonstrates that Be in aqueous solution is surrounded by four water molecules. These data support the importance of six coordination. The only exception cited here is Be, an element which obeys the octet rule. 

Gansow, O. A., Vernon, W. D., Carbon-13 Nuclear Magnetic Resonance Studies of OrganometaUic and Transition Metal Complex Compounds, Top. Carbon-13 NMR Spectrosc. 2... 

M. Kaupp and M. Biihl, Nuclear magnetic resonance (NMR) parameters of transition metal complexes methods and applications, in Encyclopedia of Inorganic and Bioinorganic Chemistry, published online 15 DEC 2011, DOI 10.1002/9781119951438.eibc0401 John Wiley Sons, Ltd. 

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