Chelated fluoroboron cations. I. Synthesis and NMR studies involving the tertiary-amine ligands N,N,N',N'-tetramethylethylenediamine and N,N,N',N",N''-pentamethyldiethylenetriamine

1999 ◽  
Vol 77 (11) ◽  
pp. 1856-1868 ◽  
Author(s):  
James AW Shoemaker ◽  
J Stephen Hartman
Keyword(s):  
Mass Spectrometry ◽  
Chemical Shifts ◽  
Chelating Ligands ◽  
Donor Molecule ◽  
Nmr Studies ◽  
Fab Mass Spectrometry ◽  
Methods Of Synthesis ◽  
Amine Ligands ◽  
Positive Ion ◽  
Nmr Signals

Several possible methods of synthesis of chelated fluoroboron cations are explored, using the tert-amines N,N,N',N'-tetramethylethylenediamine (Me4en) and N,N,N',N",N"-pentamethyldiethylenetriamine (Me5dien) as model chelating ligands. Both ligands displace pyridine from (pyr)2BF2+ (as its PF6- salt) to form the bidentate (Me4en)BF2+ and (Me5dien)BF2+ cations. The same cations, as well as the corresponding BFCl+ and BFBr+ cations, can also be prepared by displacement of the donor molecule (D = pyridine or isoxazole) and the heavy halide ion (Cl- or Br-) from the neutral D·BF2X and D·BFX2 adducts. The central nitrogen of Me5dien becomes chiral when it and one terminal nitrogen are coordinated, and the prochiral and magnetically nonequivalent fluorines of (Me5dien)BF2+ give 19F NMR signals separated by 1.2 ppm. In (Me5dien)BFCl+ the boron is a second chiral centre and the two diastereomers, distinguishable by NMR with 19F chemical shifts differing by 3.0 ppm, form in a 3:1 ratio. The bidentate BFBr+ cations of Me4en and Me5dien are insoluble in non-coordinating solvents but have been detected by positive ion FAB mass spectrometry and 11B MAS NMR. The tridentate complex (Me5dien)BF+2 does not form under our conditions.Key words: N,N,N',N'-tetramethylethylenediamine, N,N,N',N",N"- pentamethyldiethylenetriamine, chelated fluoroboron cations, fluorine-19 NMR, boron-11 NMR, pyridine, isoxazole, chiral, magnetically nonequivalent.

Chelated fluoroboron cations. III. Spectroscopic evidence for ring size and steric limitations to chelate formation by amine chelating donors

2001 ◽  
Vol 79 (4) ◽  
pp. 426-436 ◽  
Author(s):  
J Stephen Hartman ◽  
James AW Shoemaker
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Fast Atom Bombardment ◽  
Ring Size ◽  
Chelating Ligands ◽  
Factors Affecting ◽  
Spectroscopic Evidence ◽  
Chelate Formation ◽  
Amine Ligands ◽  
Chelate Rings

Factors affecting the ability of potentially chelating amine ligands to form chelated fluoroboron cations are explored by 19F and 11B NMR spectroscopy and fast atom bombardment mass spectrometry (FAB-MS). Five-membered chelate rings form much more readily than six-membered. Some potentially chelating ligands give rise to additional fluoroboron species by various redistribution and decomposition reactions.Key words: chelated fluoroboron cations, 19F NMR, 11B NMR; FAB-MS, N,N,N',N'-tetraethylethylenediamine.

scholarly journals 11B NMR Investigations of Borate Esters in Aqueous Solutions and Wine

1986 ◽  
Vol 41 (8) ◽  
pp. 1041-1044 ◽  
Author(s):  
O. Lutz ◽  
E. Veil ◽  
U. Brändle ◽  
H. Helber ◽  
E. Kämmerer ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Boric Acid ◽  
Carboxylic Acids ◽  
Chemical Shifts ◽  
Dilute Solutions ◽  
Nmr Studies ◽  
11B Nmr ◽  
Borate Esters ◽  
Hydroxy Carboxylic Acids ◽  
Nmr Signals

11B NMR studies have been performed in dilute solutions of boric acid resp. borate and some typical hydroxy-carboxylic acids as a function of pH. Typical chemical shifts have been found for the esters occurring at the different ranges of pH. The origin of the two 11B NMR signals observable in wine could be determined.

Fourier Transform NMR Studies of 95Mo and 97Mo

1976 ◽  
Vol 31 (3-4) ◽  
pp. 351-356 ◽  
Author(s):  
W. D. Kautt ◽  
H. Krüger ◽  
O. Lutz ◽  
H. Maier ◽  
A. Nolle
Keyword(s):  
Fourier Transform ◽  
Magnetic Moment ◽  
Chemical Shifts ◽  
Larmor Frequency ◽  
High Accuracy ◽  
Nuclear Magnetic Moment ◽  
Nmr Studies ◽  
Line Widths ◽  
And Shifts ◽  
Nmr Signals

95Mo and 97Mo Fourier transform NMR studies of several alkali molybdate solutions in H2O and D2O are reported. The Larmor frequency of the molybdenum nuclides is remarkably dependent on the solute and the solvent.In potassium molybdate the chemical shifts of 39K were observed. The ratio of the Larmor frequencies of 95Mo and 39K was measured with high accuracy in a 2.6 molal solution of K2MoO4 in H2O. From this value a nuclear magnetic moment of 95Mo and 97Mo in the molybdate ion was derived using the concentration dependencies of the Larmor frequencies of 39K and 95Mo and the ratio of the Larmor frequencies of 97Mo and 95Mo.In solid Ag2MoO4 and metallic molybdenum the 95Mo and 97Mo NMR signals were detected; line widths and shifts are given.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

Synthesis and characterization of 19F NMR chelators for measurement of cytosolic free Ca

1987 ◽  
Vol 252 (4) ◽  
pp. C441-C449 ◽  
Author(s):  
L. A. Levy ◽  
E. Murphy ◽  
R. E. London
Keyword(s):  
Chemical Shifts ◽  
Cell Types ◽  
Free Calcium ◽  
Tetraacetic Acid ◽  
Nmr Studies ◽  
Cytosolic Free Calcium ◽  
Fluorine Nmr ◽  
Dissociation Constant Kd

Fluorine 19 nuclear magnetic resonance (NMR) studies of intracellular fluorinated calcium chelators provide a useful strategy for the determination of cytosolic free calcium levels in cells and perfused organs. However, the fluorinated chelator with the highest affinity for calcium ions which has been described to date. 1,2-bis-(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), exhibits a dissociation constant (Kd) value 5- to 10-fold greater than the intracellular calcium concentration levels in most cell types, thus limiting the ability of fluorine NMR to report these concentrations reliably. We have consequently designed and synthesized several fluorinated calcium chelators with higher affinity for calcium. The best of these, 2-(2-amino-4-methyl-5-fluorophenoxy)-methyl-8 aminoquinidine-N,N,N',N'-tetraacetic acid (quinMF), has a Kd value approximately 10 times lower than that of 5FBAPTA. Several of the newly synthesized indicators have different chemical shifts for the calcium complexed and uncomplexed chelators to allow the simultaneous use of two indicators. In addition to providing information about the level of cytosolic free calcium, chelators containing a quinoline ring exhibit considerable sensitivity to magnesium levels and hence have potential application for the determination of cytosolic-magnesium concentrations. Application of these chelators is illustrated by determination of the cytosolic-free calcium level in erythrocytes. Use of quinMF, the chelator with the lowest Kd value, gives a calcium value of 25-30 nM.

14N-NMR-Untersuchungen an Aminophosphinen / 14N NMR Studies on Aminophosphines

1978 ◽  
Vol 33 (5) ◽  
pp. 515-520 ◽  
Author(s):  
K. Barlos ◽  
H. Nöth ◽  
B. Wrackmeyer
Keyword(s):  
Chemical Shifts ◽  
Steric Effects ◽  
Nmr Studies ◽  
Π Interactions ◽  
Nuclear Shielding ◽  
14N Nmr

Abstract14N chemical shifts of a series of cyclic and noncyclic aminophosphines are reported. The nuclear shielding of nitrogen decreases with increasing number of halogen substituents at phosphorus as well as with increasing number of phosphinyl groups attached to nitrogen. In addition to the influence of electronegativity PN(π)-interactions may account for the observed shielding. Steric effects are discussed.

Determination of Mildronate in Human Plasma and Urine by UPLC–Positive Ion Electrospray Tandem Mass Spectrometry

2011 ◽  
Vol 73 (7-8) ◽  
pp. 659-665 ◽  
Author(s):  
Li-Jing Cai ◽  
Jun Zhang ◽  
Wen-Xing Peng ◽  
Rong-Hua Zhu ◽  
Jian Yang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Human Plasma ◽  
Tandem Mass ◽  
Electrospray Tandem Mass Spectrometry ◽  
Human Plasma And Urine ◽  
Positive Ion

Definitive quantification of apolipoprotein a-I by isotope ditutioa FAB mass spectrometry

1994 ◽  
Vol 108 ◽  
pp. S193
Author(s):  
John R. Barr ◽  
Vincent L. Maggio ◽  
Louis R. Alexander ◽  
Donald G. Panerson ◽  
L.Omar Henderson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Apolipoprotein A ◽  
Fab Mass Spectrometry
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