Magnetic Resonance in Chemistry

doi: 10.1002/mrc.1260291201pmid: N/A

Diehl, P.; Ugolini, R.; Suryaprakash, N.; Jokisaari, J.

doi: 10.1002/mrc.1260291202pmid: N/A

129Xe gas to solution shifts, which generally do not correlate well with solvent parameters, are shown to be linearly related to the 13C gas to solution shifts of methane in the same solvents. Since the shifts are attributed exclusively to van der Waals effects, and 129Xe is 27.1 times more sensitive to these effects than 13C, 129Xe is suggested as a reference for van der Waals shifts induced in different nuclei.

Finocchiaro, Paolo; Mamo, Antonino; Tringali, Corrado

doi: 10.1002/mrc.1260291203pmid: N/A

The complete assignment of the proton and carbon spectra for two new 2‐pyridylquinoline ligands, 4‐phenyl‐2‐(2′‐pyridyl)quinoline (Ph‐pq) and 2,6‐di(4′‐phenylquinol‐2′‐yl)pyridine (Ph‐dqp), and their ruthenium(II) complexes [Ru(bpy)2(Ph‐pq)](PF6)2 and [Ru(Ph‐dqp)2](PF6)2 has been accomplished using a combination of one‐ and two‐dimensional NMR techniques, including COSY, NOESY, one‐bond and long‐range HETCOR and selective INEPT spectra. The J(H,H) and J(C,H) values have been determined for the majority of the resonances.

Furuhashi, Akiko; Ono, Isao; Yamasaki, Akira

doi: 10.1002/mrc.1260291204pmid: N/A

The magnetic moment of a micro‐sized solid sample can be semi‐quantitatively determined by proton magnetic resonance spectral measurement with the sample in a capillary cell coaxially placed within an NMR tube containing a suitable diamagnetic solvent with a standard such as TMS. Small signals appearing on the low‐frequency side of the main peaks can be assigned to the protons in the layer of the solution surrounding the outer surface of the coaxially placed capillary. The molar chemical shift difference of this signal splitting is proportional to the square of the magnetic moment (μ) or n(n + 2), where n is equal to the number of unpaired electrons in the sample.

Pissas, D.; Dais, Photis; Sauriol, Francoise

doi: 10.1002/mrc.1260291205pmid: N/A

13C nuclear magnetic relaxation rates were measured as a function of temperature for methyl fluorene‐3‐carboxylate and used to describe the dynamics of this molecule. The easiest reorientation is about the x principal diffusion axis, which is situated close to that inertial principal axis corresponding to the smallest moment of inertia. The reorientation of this planar asymmetric rotor is found to be anisotropic about the in‐plane x and y axes, as expected from unequal moments of inertia. The reorientation about the out‐of‐plane axis z is faster at the lowest temperature measured and it becomes comparable to the in‐plane motion at the remaining temperatures, showing decreased frictional forces for rotation in the molecular plane. Total assignment of the 1H and 13C NMR spectra of the fluorene derivative was achieved by employing 1D and 2D NMR techniques.

Page, Catherine J.; Sur, Sandip K.; Lonergan, Mark C.; Parashar, Gyanendra K.

doi: 10.1002/mrc.1260291206pmid: N/A

Yttrium(III) oxoisopropoxide, Y5O(OiPr)13, was synthesized via a new synthetic route and characterized by mass spectrometry and multinuclear magnetic resonance spectroscopic techniques. Extensive 1H, 13C and 89Y NMR studies with full assignments are reported.

Serratrice, Guy; Pastor, Raphaël; Hu, You‐Chuan

doi: 10.1002/mrc.1260291207pmid: N/A

The chemical structure of a plant growth substance, calonyctin A, was determined by NMR spectroscopy. The 13C and 1H spectral assignments were obtained using a combination of DEPT, heteronuclear chemical shift correlation, 1H–1H COSY, 1H–1H NOESY and inverse long‐range 1H–13C correlation. Calonyctin A was found to be a mixture of two homologous glycosides, each containing four rhamnoses and two aglycones. The configuration of the rhamnoses and the structural linkage between the six molecular fragments are reported.

Sokói, Maria; Grobelny, Janusz; Kowalczuk, Marek

doi: 10.1002/mrc.1260291208pmid: N/A

Potassium naphthalenide solutions in tetrahydrofuran were studied by means of 39K NMR spectroscopy. The effect of temperature, concentration and potassium cation complexation on paramagnetic shift and relaxation behaviour was demonstrated and is discussed. An attempt was made to assess the contributions due to the various relaxation mechanisms operating at different temperatures in the systems studied.

Lyčka, Antonín; Jirman, Josef; Holeček, Jaroslav

doi: 10.1002/mrc.1260291209pmid: N/A

Two‐dimensional H,C‐COSY spectra of some tetra‐, penta‐ and hexa‐coordinated organotin(IV) compounds were measured. The relative signs of nJ(119Sn,13C) and (n+1 J(119Sn,1H) coupling constants were determined after analysis of the orientation of the appropriate 119/117Sn satellites in the H,C–COSY spectra. The relative signs in BunSn and BznSn (n = 2 or 3) derivatives are opposite, whereas in Ph3Sn derivatives these signs are the same for carbon atoms in the ortho and meta positions and opposite for carbon atoms in the para positions. The same sign was found for 2J(119Sn,13C‐2) vs. 2J(119SnC1H2) in tribenzyltin(IV) chloride from the COLOC spectrum.

Kamieńska‐Trela, Krystyna; Biedrzycka, Zenobia; Da̧browski, Andrzej

doi: 10.1002/mrc.1260291210pmid: N/A

13C13C spin–spin coupling constants have been measured for a series of variously substituted ethenes. The largest 1J(CC) value, 172 Hz, was found in chlorotrifluoroethene and the smallest, 45.3 Hz, in tris(trimethylsilyl)ethene, which covers a range of 127 Hz for the 1J(CC) values. An analysis of the data revealed a large discrepancy between the experimental 1J values and those estimated by the commonly used additive increment scheme. Good agreement was found, however, between the experimental values and those calculated by means of a multiplicative scheme.