Synthesis and nuclear magnetic resonance study of the compounds (2-X-1,3-dithiane) (X = H, Me, SiMe3, GeMe3, SnMe3, PbMe3) and their tetracarbonyliron complexes

1978 ◽  
Vol 56 (11) ◽  
pp. 1538-1544 ◽  
Author(s):  
David J. Cane ◽  
William A. G. Graham ◽  
Liviu Vancea
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Energy Barrier ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Carbonyl Groups ◽  
Magnetic Resonance Study ◽  
Ring Inversion ◽  
C Nmr

A series of (1,3-dithiane)Fe(CO)4 complexes, (2-X-1,3-dithiane)Fe(CO)4, X = H, Me, SiMe3, GeMe3, SnMe3, PbMe3, has been prepared and characterized, and both the complexes and the free ligands studied by 1H and 13C nmr spectroscopy. The energy barrier to ring inversion in (1,3-dithiane)Fe(CO)4, ΔG298†, is 14.7 ± 0.2 kcal mol−1, some 4.4 kcal mol−1 higher than in free 1,3-dithiane.13C nmr spectra showed that within the Fe(CO)4 moiety, rapid averaging of carbonyl groups occurs down to at least −80 °C.

Sesquiterpene alkaloids from Tripterygiumwilfordii (Hook): a nuclear magnetic resonance study of 1-desacetylwilfordine, 1-desacetylwilfortrine, and 2-debenzoyl-2-nicotinoylwilforine

1990 ◽  
Vol 68 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Li Ya ◽  
George M. Strunz ◽  
Larry A. Calhoun
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Root Extracts ◽  
C Nmr ◽  
Nuclear Magnetic

1-Desacetylwilfordine, 8, 1-desacetylwilfortrine, 9, and 2-debenzoyl-2-nicotinoylwilforine, 10, have been isolated from root extracts of the Chinese medicinal and insecticidal plant Tripterygiumwilfordii. Analysis of the 1H and 13C NMR spectra of 8 and 10, with the aid of COSY, HCCOSY, and COLOC experiments, has allowed unambiguous chemical shift assignments of all protons and carbons of these alkaloids. Keywords: alkaloids, sesquiterpene, Celastraceae, Tripterygium, NMR.

The Lewis acid complexes of α,β-unsaturated carbonyl and nitrile compounds. A nuclear magnetic resonance study

1982 ◽  
Vol 60 (6) ◽  
pp. 801-808 ◽  
Author(s):  
Ronald F. Childs ◽  
D. Lindsay Mulholland ◽  
Alan Nixon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Group ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
C Nmr

1:1 Complexes of a range of Lewis acids with crotonaldehyde (1) have been systematically investigated by 1H and 13C nmr spectroscopy. Lewis acids employed were: BF3, BCl3, BBr3, SnCl4, TiCl4, SbCl5, AlCl3, EtAlCl2, Et2AlCl, Et3Al2Cl3, and Et3Al. Chemical shift changes in 1H nuclei remote from the Lewis acid group were found to be remarkably regular and consistent. The study has been extended to tiglaldehyde (2), pent-3-en-2-one (3), cyclohexenone (4), methyl crotonate (5), and crotonitrile (6) and the relationships between the chemical shift differences associated with complexation of these have been explored.

Hindered Rotation in Poly(N-acyl)iminoalkylenes - A 13C Nuclear Magnetic Resonance Study

1995 ◽  
Vol 50 (9) ◽  
pp. 1404-1411 ◽  
Author(s):  
Bernabé L. Rivas ◽  
Klaus Albert ◽  
Kurt E. Geckeler ◽  
Ernst Bayer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Cationic Polymerization ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Side Chain ◽  
Magnetic Resonance Study ◽  
Hindered Rotation ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr

AbstractPoly(N-acetyl)iminoethylene. poly(N-propionyl)iminoethylene and poly(N-acetyl)-2,2-dimethyliminoethylene were prepared by cationic polymerization in solution of 2-methyl- 2-oxazoline, 2-ethyl-2-oxazoline, and 2,4,4-trimethyl-2-oxazoline respectively. The 13C NMR spectra of the polymers obtained showed different sets of shifts for the carbon atoms of the backbone as well as for the N-acylimino side chain due to the restricted rotation of the Nacylimino group. The temperature dependence of the N-acylimino side chain signals showed a different coalescence behaviour depending on the substituents at both the main and the side chain.

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.

Nuclear Magnetic Resonance Study of Ring Inversion in Cycloheptene

1971 ◽  
Vol 49 (8) ◽  
pp. 1256-1261 ◽  
Author(s):  
Maurice St-Jacques ◽  
Cambyse Vaziri
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Spectral Change ◽  
Magnetic Resonance Study ◽  
Ring Inversion ◽  
Energy Profiles ◽  
Nuclear Magnetic

The p.m.r. spectrum of 4,4,5,6,6-pentadeuteriocycloheptene (3) has been studied down to −171 °C. Analysis of the spectral change below −160 °C yielded a ΔF≠ value of 5.0 kcal/mol at −165 °C. Possible energy profiles for the ring inversion of cycloheptene are discussed.

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 13C nuclear magnetic resonance study of the reversible substituent migration in several 2-acyl and 2-silyl derivatives of tropolone. Troponoid-IV

1982 ◽  
Vol 60 (3) ◽  
pp. 231-238 ◽  
Author(s):  
D. Ménard ◽  
M. St-Jacques ◽  
J. F. Bagli
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Energy Barrier ◽  
Bromine Atom ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
13C Nuclear Magnetic Resonance ◽  
Silyl Derivatives ◽  
Derivatives Of ◽  
Nuclear Magnetic

The energy barrier for the reversible substituent migration was determined for a number of 2-acyl and 2-silyl derivatives of tropolone. The energy barrier is found to be dependent on the nature of the migrating group. Asymmetric monosubstitution on the ring shifts the equilibrium in favor of one dynamic isomer. In the two cases studied (3-bromotropolone and 3-bromotropolone acetate) it is found that the equilibrium is shifted towards the isomer bearing the bromine atom at the 7-position.

1H and 13C nuclear magnetic resonance study of the complexation of uranyl ion with malic acid

1982 ◽  
Vol 60 (8) ◽  
pp. 1007-1018 ◽  
Author(s):  
M. Teresa Nunes ◽  
Victor M. S. Gil ◽  
António V. Xavier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Malic Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Molar Ratios ◽  
Nmr Study ◽  
13C Nuclear Magnetic Resonance ◽  
Ph Range ◽  
C Nmr

A full pH range 1H and 13C nmr study was performed of the complexation of UO22+ with malic acid, for variable concentrations and molar ratios. Spectral evidence for the existence of at least five complexes was found, and their stoichiometry and dependence on pH were investigated. Information on the conformation of the bound ligand molecules was also obtained.

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