Spin-spin coupling in magnetically condensed complexes. XI. Out-of-plane interactions and triplet ground state in tetrakis(N,N-diethyldithiocarbamato)dicopper(II)

1971 ◽  
Vol 10 (9) ◽  
pp. 2038-2041 ◽  
Author(s):  
Juan F. Villa ◽  
William E. Hatfield
Keyword(s):  
Ground State ◽  
Spin Coupling ◽  
Triplet Ground State ◽  
Out Of Plane ◽  
Spin Spin Coupling ◽  
Condensed Complexes

In-plane and out-of-plane conformational preferences of the sulfhydryl group in some halothiophenol derivatives

1979 ◽  
Vol 57 (12) ◽  
pp. 1421-1425 ◽  
Author(s):  
Ted Schaefer ◽  
William J. E. Parr
Keyword(s):  
Sulfhydryl Group ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Group ◽  
Recent Analysis ◽  
Phenol Derivatives ◽  
Out Of Plane ◽  
Intramolecular Hydrogen ◽  
Cis And Trans ◽  
Spin Spin Coupling

Long-range spin–spin coupling constants between sulfhydryl protons and ring protons in some halothiophenol derivatives in CCl4 solutions are reported. In contrast to the corresponding phenol derivatives, substantial amounts of out-of-plane conformers are present at 305 K for all but 2,6-dichlorothiophenol. The cis and trans conformers differ by only about 0.2 kcal/mol in free energy for 2,4-dibromothiophenol and 2,4-dichlorothiophenol, in good agreement with a recent analysis of the dipole moment observed for the latter compound. The barrier to internal rotation of the sulfhydryl group is considerably smaller than for a hydroxyl group and rough estimates are given for the barrier in a few compounds. For example, the barrier in 2,3,5,6-tetrafluorothiophenol is lower than in 2,6-dichlorothiophenol. STO-3G MO calculations overestimate the internal barrier to rotation of the sulfhydryl group, but yield charge densities for this group which indicate that a major cause of the relative weakness of its intramolecular hydrogen bonds resides in its lack of polarity.

Orbital ground state, crystal field splittings, and magnetic hyperfine interactions in iron(II) fluorosulphate

1977 ◽  
Vol 55 (1) ◽  
pp. 115-121 ◽  
Author(s):  
John R. Sams ◽  
Robert C. Thompson ◽  
Tsang Bik Tsin
Keyword(s):  
Crystal Field ◽  
Ground State ◽  
Hyperfine Interactions ◽  
Excited Level ◽  
Quadrupole Coupling Constant ◽  
Spin Coupling ◽  
Rhombic Distortion ◽  
Constant E ◽  
Jahn Teller ◽  
Spin Spin Coupling

Magnetic susceptibilities between 80 and 300 K and 57Fe Mössbauer parameters between 4.2 and 295 K are reported for Fe(SO3F)2. These data have been analysed via a crystal field model including spin–orbit and spin–spin coupling. The compound is trigonally distorted by an elongation along the [111] axis of the FeO6 octahedron, and the ground state is the orbital doublet [Formula: see text]. The quadrupole coupling constant e2qQ is positive, and no rhombic distortion could be detected. The electronic spectrum shows a splitting of the 5Eg excited level, presumably by a dynamic Jahn–Teller effect, and [Formula: see text] Attempts to fit a low-temperature magnetic perturbation Mössbauer spectrum using a pseudo-spin Hamiltonian were only partially successful, but suggest that the g tensor is highly anisotropic with [Formula: see text] and that the internal hyperfine field is small. Spin relaxation in Fe(SO3F)2 is fast at all temperatures down to 4.2 K and in applied magnetic fields of up to 5.0 T.

Proton and fluorine magnetic resonance studies of some benzoyl fluoride derivatives. Sensitivity of the fluorine shifts to intramolecular van der Waals interactions and steric effects

1977 ◽  
Vol 55 (22) ◽  
pp. 3936-3941 ◽  
Author(s):  
Ted Schaefer ◽  
Kirk Marat ◽  
Kalvin Chum ◽  
Alexander F. Janzen
Keyword(s):  
Magnetic Resonance ◽  
Van Der Waals ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Van Der Waals Interactions ◽  
Proton Proton ◽  
Out Of Plane ◽  
Spin Coupling Constants ◽  
The Individual ◽  
Spin Spin Coupling

The syntheses and the analyses of the high resolution proton and fluorine magnetic resonance spectra of the 3-fluoro-4-methyl-, 2-fluoro-5-chloro-, 2-fluoro-6-chloro-, 2,6-difluoro-, and of the pentafluorobenzoyl fluorides are reported. The spin–spin coupling constants over five bonds between the sidechain fluorine-19 and the ring protons are sensitive to intrinsic substituent perturbations. Their use in the deduction of conformational preferences is much more problematical than is the use of the corresponding proton–proton couplings in benzaldehyde derivatives. The 2-fluoro-6-chloro compound is nonplanar, as indicated by a finite magnitude of the long-range proton–fluorine coupling over six bonds. The nonplanarity is also indicated by a comparison of the through-space fluorine–fluorine coupling to those in the other compounds. The chemical shift of the sidechain fluorine moves to low field by over 35 ppm as the size of the two ortho substituents increases. The individual shifts are discussed in terms of intramolecular van der Waals interactions and of out-of-plane twisting of the COF group.

scholarly journals Conducting High-Spin (S = 1) Organic Diradical with Robust Stability

2020 ◽  
Author(s):  
Shuyang Zhang ◽  
Maren Pink ◽  
Tobias Junghoefer ◽  
Wenchao Zhao ◽  
Sheng-Ning Hsu ◽  
...  
Keyword(s):  
Thin Films ◽  
Robust Stability ◽  
Ground State ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Paramagnetic Resonance ◽  
Triplet Ground State ◽  
Out Of Plane ◽  
Electron Paramagnetic

Triplet ground-state organic molecules are of interest with respect to several emerging technologies but usually show limited stability, especially, as thin films. We report an organic diradical, based entirely on two Blatter radicals, that possesses triplet ground state (2J/k ≈ 220 K, EST ≈ 0.4 kcal mol-1 ) and robust stability, with onset of decomposition above 264 C (TGA). Polycrystalline diradical is a good electrical conductor with conductivity comparable to the out-of-plane conductivity in highly oriented pyrolytic graphite (HOPG). The diradical is evaporated under ultra-high vacuum to form thin films, which are stable on air for at least 18 and 48 h, as demonstrated by X-ray photoelectron and electron paramagnetic resonance (EPR) spectroscopies, respectively. <br>

The sign of the 'through-space' spin–spin coupling between methyl protons and the fluorine nucleus in 2,6-dimethylbenzoyl fluoride

1976 ◽  
Vol 54 (5) ◽  
pp. 800-804 ◽  
Author(s):  
Ted Schaefer ◽  
Kalvin Chum ◽  
Kirk Marat ◽  
Roderick E. Wasylishen
Keyword(s):  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Fluorine Nucleus ◽  
Methyl Group ◽  
Out Of Plane ◽  
Spin Spin Coupling ◽  
Coupling Mechanisms ◽  
Carbonyl Fluoride

The spin–spin coupling constant over five formal bonds between 19F and methyl protons, [Formula: see text], in 2,6-dimethylbenzoyl fluoride is −3.1 Hz. Observation of a nonzero [Formula: see text] indicates an out-of-plane conformation for the carbonyl fluoride group and implies substantial nonbonded repulsions between the methyl and carbonyl fluoride groups. It is argued that [Formula: see text] is as small as −7 Hz when the C—F bond lies cis to a methyl group and that its magnitude is a consequence of the so-called 'through-space' coupling mechanisms. On the basis of INDO–MO–FPT computations, it is suggested that such observed couplings are a composite of large contributions of either sign and, therefore, that observed through-space 1H,19F couplings may be of either sign if conformational averaging occurs.

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