Solution dynamics of the osmium cluster [Os3(µ-H)2(CO)10] by13C and17O nuclear magnetic resonance. Estimation of the13C chemical shift anisotropy and17O quadrupole coupling constant
- 1 January 1984
- journal article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 2,p. 279-284
- https://doi.org/10.1039/dt9840000279
Abstract
Application of the saturation-transfer technique to 13C n.m.r. spectra of 13C-enriched [Os3(µ-H)2(CO)10] shows that only localised 13C exchange occurs, involving two of the four types of carbonyl ligand. Equations are derived to describe the recovery of the exchanging AX2 spin system towards equilibrium, after an initial perturbation. When the initial perturbation is a selective inversion of A or X2, values for the 13C relaxation parameters and the A X2 exchange rate constant can be determined. The rate constant for this localised process is 0.36 s–1 at 300 K in CDCl3 solution. An estimate of the quadrupole coupling constant for 17O in the complex (1.59 MHz), together with 17O spin-lattice relaxation time measurements, yielded a value for the correlation time for molecular reorientation of 22 ± 4 ps. The 13C spin-lattice relaxation rates are strongly field dependent and values for the 13C shielding anisotropy in the region of 383 ± 50 p. p. m. were obtained.Keywords
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