Y nmr spectroscopy

In order to obtain information on the cellular responses to the added vanadium(V) spectroscopic studies were carried out (Figure 5). Centrifugation of growth samples led to a media and cell fraction that were investigated by Y NMR spectroscopy, hi the absence of yeast the 5.0 mM vanadate had formed mainly Vio with a small component ofV, in the media at pH 4.0 Vj and V4 were predominant in the media at pH 6.5 as observed in the V... 

Several of the metals have spin-active nuclei and this sometimes allows direct observation using NMR spectroscopy, e.g. has a shift range >1000 ppm and Y NMR spectroscopy is valuable for characterizing yttrium-containing compounds. In general, it is more convenient to make use of the coupling of metal nuclei to more easily observed nuclei such as h, or P. Some examples of nuclei with I = are... 

The study of yttrium cyclopentadienyl complexes by Y NMR spectroscopy has shown that the magnetic shielding of the metal atom significantly depends on its ligand surrounding [216]. 

Lu(N03)2(H20)2]" species. The presence of mono- and dinitrato complexes in these solutions is entirely analogous to the results obtained by H- and Y-NMR spectroscopy for yttrium solutions (Fratiello et al. 1989a, 1994). 

Barbate G, Ikura M, Kay L E, Pastor R W and Bax A 1992 Backbone dynamics of calmodulin studied by N relaxation using inverse detected two-dimensional NMR spectroscopy the central helix is flexible S/oefrem/sf/ y 31 5269-78... 

G. Binsch, Top. Stereochem. 3 97 (1968) F. G. Riddell, Nucl. Magn. Reson. 12 246 (1983) J. Sandstrom, Dynamic NMR Spectroscopy Academic Press, New %rk, 1982 J. L. Marshall, Nuclear Magnetic Resonance, Veilag Chemie, Deerfield Beach, Florida, 1983 M. Oki, Applications of Dynamic NMR to Organic Chemistry, VCH Publishers, Deerfield Beach, Florida, 1985 Y. Takeuchi and A. P. Marchand, eds.. Applications of NMR Spectroscopy in Stereochemistry and Corformationol Analysis, VCH Publishers, Deerfield Beach, Florida, 1986. 

Diastereoselecbvity was deterrmned by NMR spectroscopy and by gas chromatographic analysis (50 m y 0 025 mm OV-101 open mbular column)... 

Vicinal coupling (Section 13.7) Coupling of the nuclear spins of atoms X and Y on adjacent atoms as in X—A—B—Y. Vicinal coupling is the most common cause of spin-spin splitting in FI NMR spectroscopy. 

FIGURE 18.14 With NMR spectroscopy one can observe the metabolism of a living subject in real time. These NMR spectra show the changes in ATP, creadne-P (phosphocre-adne), and P levels in the forearm muscle of a human subjected to 19 minutes of exercise. Note that the three P atoms of ATP a, /3, and y) have different chemical shifts, reflecting their different chemical environments. 

Hydrogen as it occurs in nature is predominantly composed of atoms in which the nucleus is a single proton. In addition, terrestrial hydrogen contains about 0.0156% of deuterium atoms in which the nucleus also contains a neutron, and this is the reason for its variable atomic weight (p. 17). Addition of a second neutron induces instability and tritium is radioactive, emitting low-energy particles with a half-life of 12.33 y. Some characteristic properties of these 3 atoms are given in Table 3.1, and their implications for stable isotope studies, radioactive tracer studies, and nmr spectroscopy are obvious. 

Phosphorus has only one stable isotope, J P, and accordingly (p. 17) its atomic weight is known with extreme accuracy, 30.973 762(4). Sixteen radioactive isotopes are known, of which P is by far the most important il is made on the multikilogram scale by the neutron irradiation of S(n,p) or P(n,y) in a nuclear reactor, and is a pure -emitter of half life 14.26 days, 1.7()9MeV, rntan 0.69MeV. It finds extensive use in tracer and mechanistic studies. The stable isotope has a nuclear spin quantum number of and this is much used in nmr spectroscopy. Chemical shifts and coupling constants can both be used diagnostically to determine structural information. 

The reaction is carried out in both acidic and basic media. Thus, for example, the interaction of 4-diethylaminobut-3-en-2-one with thiocarbamide is performed at 75°C for 30 h (EtOK, EtOH) to result in 54% yield of the major product. The existence of two tautomers 274 and 275 was proved for 2-mercapto-4-methylpyrimidine (Y = S) by IR and H NMR spectroscopy (76ZOR2063). 

Carboxylic acid groups can be detected by both and A3C NMR spectroscopy. Carboxyl carbon atoms absorb in the range 165 to 185 8 in the l3C NMR spectrum, with aromatic and unsaturated acids near the upheld end of the range (—165 8) and saturated aliphatic acids near the downfield end (—185 8). Nitrile carbons absorb in the range 115 to 130 8. 

For product 1 (X = Y = H) an equilibrium between the two possible double-bond isomers has been detected by NMR spectroscopy. For the dibromo derivative (X = Y = Br) a tub conformation has been determined by X-ray structural analysis. 

Chemical bonding and dynamic properties of Au clusters are obtained by recoilless y-ray spectroscopy and- P NMR investigations - . ... 

H NMR spectroscopy studies of iron(IIl) a-alkyl and o-aryl porphyrins have been very important in elucidating spin states. Alkyl and most aryl complexes with simple porphyrin ligands (OEP, TPP, or TTP) are low spin, S — I /2 species. NMR spectra for the tetraarylporphyrin derivatives show upheld resonances for the porphyrin pyrrole protons (ca. — 18 to —35 ppm), and alternating upfield and downfield hyperfine shifts for the axial alkyl or aryl resonances. For -alkyl complexes, the a-protons show dramatic downfield shifts (to ca. 600 ppm), upfield shifts for the /3-protons (—25 to — 160 ppm) and downfield shifts for the y-protons (12 ppm). The cr-protons of alkyliron porphyrins are not usually detected as a result of their large downfield shift and broad resonance. These protons were first detected by deuterium NMR in the dcuterated complexes Fe(TPP)CD3 (532 ppm) and Fe(TPP)CD2CDi (562, -117 ppm). ... 

Transverse magnetization Magnetization existing in the x y -plane. Transverse operators Designated as /, or /, in the product operator description of NMR spectroscopy. 

Propyhdyne formed from propene on lr4 supported on y-Al203 was observed by IR and NMR spectroscopies [38]. When ethene or propene was brought in contact with oxide-supported lr4 [39,40], Ire [39,40], or Rhe (A.M. Argo and B.C. Gates BC, impubhshed results) in the presence of H2, hydrocarbon hgands were formed (namely, alkyls and /r-bonded alkenes), which have been inferred from IR spectra to be intermediates in hydrogenation to make alkanes, as discussed later. The population of these hydrocarbon ligands on the supported clusters depends sensitively on the conditions, such as reactant partial pressures and temperature. 

M. Maiwald, H. H. Fischer, Y.-K. Kim, K. Albert, H. Hasse 2004, (Quantitative high-resolution on-line NMR spectroscopy in reaction process monitoring), /. Magn. Reson. 166, 135. 

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