Mercury(I) chemistry. Part I. Complexes of the mercurous ion with some arenes

1976 ◽  
Vol 54 (1) ◽  
pp. 166-176 ◽  
Author(s):  
Philip A. W. Dean ◽  
David G. Ibbott ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Sulfur Dioxide ◽  
Binding Sites ◽  
Chemical Shifts ◽  
Formation Constants ◽  
Resonance Spectroscopy ◽  
Arene Complexes ◽  
Liquid Sulfur ◽  
Wide Range ◽  
Mercurous Ion

A wide range of arene complexes of the mercurous ion has been prepared from mercurous hexafluoroarsenate and the appropriate arene in liquid sulfur dioxide. Raman spectroscopy confirmed the integrity of the dimeric Hg22+ cation in these complexes. 13C nuclear magnetic resonance spectroscopy showed that Hg22+–arene complexes exist in sulfur dioxide solution. The 13C data allowed the estimation of formation constants for the hexamethylbenzene, p-xylene, and p-dichlorobenzene complexes together with the 13C chemical shifts for the bound substrates in these cases. The 13C chemical shift changes (relative to the free substrate) on addition of Hg22+ to SO2 solutions of various methylated benzenes are compared with those occurring on complexation of the same arenes by the argentous ion and the Cr(CO)3 moiety. In mercurous ion–arene complexes, it is concluded that the cation is involved in a localized interaction with the arene and that there are preferred binding sites. These sites may be identified by the complexation shifts for the Ag+– and Hg22+–arene complexes.

Nuclear magnetic resonance studies of the solution chemistry of metal complexes. XVII. Formation constants for the complexation of methylmercury by sulfhydryl-containing amino acids and related molecules

1981 ◽  
Vol 59 (10) ◽  
pp. 1505-1514 ◽  
Author(s):  
R. Stephen Reid ◽  
Dallas L. Rabenstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Formation Constants ◽  
Solution Chemistry ◽  
The Other ◽  
Mercaptoacetic Acid ◽  
Resonance Spectroscopy ◽  
Mercaptosuccinic Acid ◽  
Wide Range ◽  
Nuclear Magnetic

Complexation of methylmercury, CH3Hg(II), by mercaptoacetic acid, mercaptoethanol, mercaptosuccinic acid, cysteine, penicillamine, homocysteine, and N-acetylpenicillamine has been studied by 1H nuclear magnetic resonance spectroscopy. The equilibrium constant for displacement of mercaptoacetic acid from its CH3Hg(II) complex by each of the other thiols was measured over a wide range of pH. From the displacement constants and a literature value for the formation constant of the mercaptoethanol complex of CH3Hg(II), formation constants were calculated for thiol complexes with the other ligands, including microscopic formation constants for cysteine and penicillamine complexes in which the amino groups are protonated and deprotonated. Detailed information on the acid–base chemistry of the free amino and carboxylic acid groups in the complexes is also reported. The formation constants increase as the Brønsted basicity of the deprotonated sulfhydryl group increases according to the relation log Kf = pK + 6.86. The conditional formation constants of the CH3Hg(II) complexes are strongly pH dependent due to competitive reactions involving hydrogen and hydroxide ions at low and high pH. The results at physiological pH are discussed with reference to the effectiveness of mercaptosuccinic acid, N-acetylpenicillamine, and penicillamine as antidotes for methylmercury poisoning.

A nuclear magnetic resonance study of hydrogen bonding of δ-valerolactam

1969 ◽  
Vol 47 (19) ◽  
pp. 3655-3660 ◽  
Author(s):  
J. M. Purcell ◽  
H. Susi ◽  
J. R. Cavanaugh
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Bond Formation ◽  
Resonance Spectroscopy ◽  
Hydrogen Bond Formation ◽  
Wide Range ◽  
Nuclear Magnetic

The association of amide groups of δ-valerolactam through hydrogen bonding has been investigated by means of high resolution nuclear magnetic resonance spectroscopy in CCl4 and CDCl3 solutions. Chemical shifts of the NH proton signal were measured over a wide range of temperatures and concentrations. Thermodynamic properties associated with the [Formula: see text] hydrogen bond formation were evaluated from a least squares analysis by a direct search procedure with a digital computer. The obtained enthalpy values for hydrogen bond formation are in general agreement with results obtained by other methods.

Studies of specifically fluorinated carbohydrates. Part II. Nuclear magnetic resonance studies of pentopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 19-30 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Studies ◽  
Conformational Model ◽  
Nuclear Magnetic

Detailed studies, by 1H and 19F nuclear magnetic resonance spectroscopy, of a series of fully esterified pentopyranosyl fluorides, show that all such derivatives favor that conformer in which the fluorine substituent is axially oriented. This conclusion is supported by separate considerations of the vicinal and geminal19F–1H and 1H–1H coupling constants, of the long-range (4J) 1H–1H and 19F–1H coupling constants and of the 19F chemical shifts. The limitations of the above conformational model are discussed.

Nuclear magnetic resonance studies of the solution chemistry of metal complexes. XV. Trimethyllead complexes of inorganic ligands

1978 ◽  
Vol 56 (24) ◽  
pp. 3104-3108 ◽  
Author(s):  
Emiko K. Millar ◽  
Christopher A. Evans ◽  
Dallas L. Rabenstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Biological Fluids ◽  
Formation Constants ◽  
Solution Chemistry ◽  
Resonance Spectroscopy ◽  
Ligand Type ◽  
Conjugate Bases ◽  
Inorganic Ligands ◽  
Nuclear Magnetic

The formation constants of the trimethyllead(IV) complexes of SO32−, SeO32−, S2O32−, SCN−, HPO42−, CO32−, Cl−, Br−, and I− have been determined in aqueous solution by 1H nuclear magnetic resonance spectroscopy. The formation constants are in general fairly small and the extent to which complexes form is strongly dependent on pH. At high pH (CH3)3PbOH forms while at low pH protonation of those ligands which are the conjugate bases of weak acids competes with complex formation. There is no indication of high selectivity in the binding of trimethyllead(IV) by a particular ligand type, and calculations indicate that trimethyllead(IV) is likely to be distributed among a variety of ligands in biological fluids, including chloride which forms uncharged and presumably lipid soluble (CH3)3PbCl.

scholarly journals Study of the biologically active acyclic ureas by nuclear magnetic resonance

2020 ◽  
Vol 100 (4) ◽  
pp. 60-74
Author(s):  
А.А. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
V.S. Malkov ◽  
R.Sh. Еrkasov ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Biologically Active ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Nuclear Magnetic

A wide variety of acyclic ureas comprising alkyl, arylalkyl, acyl, and aryl functional groups are investigated by nuclear magnetic resonance spectroscopy. In general, spectral characteristics of more than 130 substances based on acyclic ureas dissolved in deuterated dimethyl sulfoxide at room temperature are studied. The re-sults obtained based on the studies of 1H and 13C NMR spectra of urea and its N-alkyl-, N-arylalkyl-, N-aryl- and 1,3-diaryl derivatives are presented, and the effect of these functional groups on the chemical shifts in carbonyl and amide moieties in acyclic urea derivatives is discussed. An introduction of any type of substitu-ent (electron-withdrawing or electron-donating) into urea molecule is stated to result in a strong upfield shift in 13C NMR spectra relatively to unsubstituted urea. A strong sensitivity of NH protons to the presence of acyl and aryl groups in nuclear magnetic resonance spectra is pointed out. In some cases, qualitative depend-encies between the chemical shifts in the NMR spectra and the structure of the studied acyclic ureas are re-vealed. A summary of the results on chemical shifts in the NMR spectra of the investigated substances allows determining the ranges of chemical shift variations of the key protons and carbon atoms in acyclic ureas. The literature describing the synthesis procedures are provided. The results obtained significantly expand the methods of reliable identification of biologically active acyclic ureas and their metabolites that makes it promising to use NMR spectroscopy both in biochemistry and in clinical practice.

A Nuclear Magnetic Resonance Study of the Metal Binding Sites in Bacitracin

1975 ◽  
Vol 53 (12) ◽  
pp. 1250-1254 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Moira R. Graham
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Metal Binding ◽  
Binding Sites ◽  
Imidazole Ring ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Metal Binding Sites ◽  
Ph Values ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance spectroscopy has been used to identify sites in bacitracin which bind Cu2+ and Mn2+. Results are presented which implicate the free carboxyl groups of the aspartic and glutamic acid residues and the imidazole ring of the histidine residue as metal complexation sites between pH 6 and 8. Evidence is presented which also indicates that the thiazoline ring of bacitracin binds Mn2+. Bacitracin does not bind Cu2+ or Mn2+ at pH values of 2.5 or less.

Sign in / Sign up

Export Citation Format

Share Document