15N and 77Se Nuclear Magnetic Resonance Study of Selenium Diimides and Aminoselenanes

1993 ◽  
Vol 48 (10) ◽  
pp. 1307-1314 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Berthold Distler ◽  
Silke Gerstmann ◽  
Max Herberhold
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Decomposition Product ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Study ◽  
Nmr Data ◽  
Cp Mas Nmr ◽  
Membered Heterocycle

Selenium diimides R(NSeN)R [R = tBu (1a), tOct (1b)], the eight-membered heterocycle tBuN(SeSeSe)2NtBu (2) and the aminoselenanes of the type [R(Cl3Si)N]2Se (4a,b) and [(Me3Si)2N]2Se (5) were studied by multinuclear NMR with emphasis on 15N NMR for detection of coupling constants J(77Se15N). The selenium diimides possess the largest values of 1J(77Se15N) observed so far (1a: 158.4 and 163.5 Hz; 1 b: 158.6 and 162.8 Hz). Compound 1 b was found to be much more stable than 1a, the heterocycle 2 being the major decomposition product of 1a. The selenium diimides (1a,b) react readily with hexachlorodisilane to give the bis[alkyl(trichlorosilyl)amino]selenanes 4a,b. The solid state 13C, 15N, 29Si and 77Se CP/MAS NMR spectra of bis[bis(trimethylsilyl)amino]selenane (5) gave results in accord with the known crystal structure, and there is agreement with the solution state NMR data

13C nuclear magnetic resonance study of cyclodipeptides containing 13C enriched hydrophobic amino acids

1980 ◽  
Vol 45 (2) ◽  
pp. 482-490 ◽  
Author(s):  
Jaroslav Vičar ◽  
François Piriou ◽  
Pierre Fromageot ◽  
Karel Bláha ◽  
Serge Fermandjian
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Magnetic Resonance Study ◽  
Side Chain Conformation ◽  
13C Nuclear Magnetic Resonance ◽  
Hydrophobic Amino Acids

The diastereoisomeric pairs of cyclodipeptides cis- and trans-cyclo(Ala-Ala), cyclo(Ala-Phe), cyclo(Val-Val) and cyclo(Leu-Leu) containing 85% 13C enriched amino-acid residues were synthesized and their 13C-13C coupling constants were measured. The combination of 13C-13C and 1H-1H coupling constants enabled to estimate unequivocally the side chain conformation of the valine and leucine residues.

Nuclear magnetic resonance studies on the anions [M(SnCl3)5Cl]4− (M = Ru, Os) and [Ru(SnCl3)5(MeCN)]3−: the X-ray crystal structure of [N(C2H5)4]4[Ru(SnCl3)5Cl]

1982 ◽  
Vol 60 (11) ◽  
pp. 1304-1316 ◽  
Author(s):  
Louis J. Farrugia ◽  
Brian R. James ◽  
Claude R. Lassigne ◽  
Edward J. Wells
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Octahedral Geometry ◽  
Coupling Constants ◽  
Order Effects ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
Crystallographic Study

The octahedral anions [M(SnCl3)5Cl]4− (M = Ru, Os) have been fully characterized by 119Sn FT nmr spectroscopy. For M = Ru, 117Sn and 115Sn nmr spectra were also recorded, and an X-ray crystallographic study was carried out on the tetraethylammonium salt, isolated as a disolvate from acetonitrile. The Ru—Sn bond lengths indicate some degree of dπ–dπ interactions. The slight distortions from octahedral geometry are discussed in connection with the packing of the chlorine atoms. The Sn nmr spectra reveal the first observed coupling to a 99Ru nucleus (I = 5/2, 12.7% natural abundance), very large 2J(119Sn—117Sn) coupling constants, and the first observed second-order effects on a heteronuclear system. The octahedral anion [Ru(SnCl3)5(MeCN)]3− was also synthesized as the tetraethylammonium salt and characterized spectroscopically.

A 19F nuclear magnetic resonance study of the conjugate Brönsted-Lewis superacid HSO3F-SbF5. Part 1

1999 ◽  
Vol 77 (11) ◽  
pp. 1869-1886 ◽  
Author(s):  
Dingliang Zhang ◽  
Markus Heubes ◽  
Gerhard Hägele ◽  
Friedhelm Aubke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Formation Reaction ◽  
H Nmr ◽  
Acid Conjugate ◽  
Nmr Methods ◽  
Cis And Trans

The Brönsted-Lewis superacid HSO3F-SbF5 or "magic acid" is re-investigated by modern 19F NMR methods over a wide concentration range. The system is found to be considerably more complex than had been assumed previously. A total of 13 different anions are identified of which only five have previously been identified in magic acid. With increasing SbF5 contents the concentration of monomeric anions like [SbF6]-, [SbF5(SO3F)]-, cis- and trans-[SbF4(SO3F)2]-, and mer-[SbF3(SO3F)3]- gradually decreases. Except for [Sb2F11]-, which is present in very small concentrations only, the formation of oligomers involves exclusively μ-fluorosulfato bridges. In addition to donor (SO3F)- and acceptor (SbF5) complex formation to give [SbF5(SO3F)]- and possibly ligand redistribution, the solvolysis of SbF5 or SbF4(SO3F) in HSO3F appears to be the principal formation reaction for polyfluorosulfatofluoroantimonate(V) anions. In glass (NMR tubes) the solvolysis product HF is converted to the oxonium ion [H3O]+, which has previously been identified by 1H NMR and structurally characterized as [H3O][Sb2F11] by us.Key words: magic acid, conjugate superacid, fluorosulfuric acid, 19F NMR spectra.

Antimony-121 nuclear magnetic resonance study of hexahaloantimonate anions

1981 ◽  
Vol 59 (20) ◽  
pp. 2940-2949 ◽  
Author(s):  
R. Garth Kidd ◽  
H. Garth Spinney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Central Atom ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Acetonitrile Solution ◽  
Trans Isomers ◽  
Magnetic Resonance Study ◽  
Chlorine Substitution ◽  
Nuclear Shielding

The seven hexahaloantimonate anions in the series [SbClnBr6−n]− have been prepared and their antimony-121 nmr spectra show that for [SbCl4Br2]−, [SbCl3Br3]−, and [SbCl2Br4]−, only the cis isomers are present in acetonitrile solution. The pairwise additivity model for central atom shielding has been used for configuration assignments. Models relevant to the higher incidence of cis over trans isomers are discussed. The nuclear shielding of 121Sb is the most sensitive to halogen substitution of all the elements whose halide chemical shifts have been studied. Antimony shieldings exhibit normal halogen dependence, with bromine substitution causing upfield shifts relative to chlorine substitution.

A nuclear magnetic resonance study of Al–Mn quasicrystals and related materials

1987 ◽  
Vol 2 (4) ◽  
pp. 431-435 ◽  
Author(s):  
Keith R. Carduner ◽  
B. H. Suits ◽  
J. A. DiVerdi ◽  
Michael D. Murphy ◽  
David White
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Melt Spinning ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Broad Distribution ◽  
Quadrupole Field ◽  
Melt Spinning Technique ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) results are presented for several aluminum alloy samples prepared using the melt-spinning technique including orthorhombic Al6Mn, Al–Mn quasicrystals both with and without doping with Si and Ru, and a T-phase alloy of Al and Pt. With the exception of the orthorhombic material, all of the NMR spectra show a broad distribution of sites. No features unique to the quasicrystal phase are observed. For the orthorhombic material the quadrupole field parameters are found to be ∥VQ∥ − 1.0±0.1 MHz and η = 0.4±0.1.

A wide-line nuclear magnetic resonance study of molecular motions in piperidinium salts

1976 ◽  
Vol 54 (22) ◽  
pp. 3483-3486 ◽  
Author(s):  
Marie-Claude Bernard ◽  
Christopher Orvig ◽  
D. F. R. Gilson
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Differential Scanning Calorimetric ◽  
Temperature Phase ◽  
Molecular Motions ◽  
Magnetic Resonance Study ◽  
Line Nuclear Magnetic Resonance ◽  
Wide Line ◽  
Calorimetric Studies

Wide line nmr and differential scanning calorimetric studies confirm the existence of crystal phase transitions in piperidinium iodide. The highest temperature phase involves isotropic rotation of the piperidinium ion. No crystal structure transitions occur in the chloride, bromide, or hexafluorophosphate salts although these compounds undergo second moment transitions indicating probable rotation of the piperidinium ion about the N—C3 axis.

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