Relaxation by Chemical Shift Anisotropy, Spin-Rotation Relaxation, Scalar Relaxation of the Second Kind and Cross-Mechanisms

1985 ◽  
Vol 40 (12) ◽  
pp. 1763-1765 ◽  
Author(s):  
Reinhard Benn ◽  
Herbert Brenneke ◽  
Rolf-Dieter Reinhardt

Abstract At 9.4 T the I03Rh relaxation times (T ,) of unsym metrical organorhodium com pounds of the type LR h(7r-ligand) 2 are in the order of seconds, and relaxation is dominated by the Chemical Shift Anisotropy mechanism. In symmetrical complexes like (acac)3Rh (7), T, of 103Rh is considerably longer and dominated by the Spin Rotation mechanism. Through this effect, together with selective polarisation transfer via the Rh olefin-proton spin-spin couplings at high magnetic fields, a significantly improved detection of the insensitive Rh nucleus results


1991 ◽  
Vol 69 (7) ◽  
pp. 1054-1056 ◽  
Author(s):  
Glenn H. Penner

Selenium-77 and phosphorus-31 spin-lattice relaxation times are reported for tri-tert-butylphosphine selenide in chloroform-d, at 303 K and at several different magnetic field strengths. At moderate fields the 31P–1H dipole–dipole, spin-rotation, and chemical shift anisotropy mechanisms contribute significantly towards the 31P T1. At high fields chemical shift anisotropy dominates. The selenium-77 nuclear spin relaxes almost exclusively by spin rotation at low to moderate fields and the chemical shift anisotropy contribution only becomes significant at very high fields. This is due to an unusually small 77Se CSA. The contribution due to 31P–77Se dipole–dipole interactions is small but significant. Key words: 77Se NMR, NMR relaxation, phosphine selenide.


1997 ◽  
Vol 119 (6) ◽  
pp. 1336-1345 ◽  
Author(s):  
Gyula Batta ◽  
Katalin E. Kövér ◽  
Jacquelyn Gervay ◽  
Miklós Hornyák ◽  
Gareth M. Roberts

1993 ◽  
Vol 2 (3) ◽  
pp. 105-110 ◽  
Author(s):  
U Scheler ◽  
B Blümich ◽  
H.W Spiess

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