Studies of tungsten-183 magnetic shielding by heteronuclear magnetic double and triple resonance
- 1 January 1976
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 16,p. 1616-1622
- https://doi.org/10.1039/dt9760001616
Abstract
1 H-{183W}, 1H-{31P}, and 1H-{183W, 31P} nuclear magnetic double- and triple-resonance experiments have been used to determine tungsten-183 chemical shifts and other parameters in 35 tungsten(0) complexes with tertiary phosphine, η-cyclopentadienyl, and other ligands. The observed chemical shifts are several thousand p.p.m. to high field of those for derivatives of WF6, and this is attributed to the occupancy of the dxy, dyz and dxz valence orbitals in addition to the dx2–y2, and dz2, which reduces the delectron imbalance and gives a smaller paramagnetic term. π-Back bonding with ligands produces a high-field shift and the marked sensitivity of the shielding to temperature and isotopic substitution is attributed to changes in electronic excitation energies.Keywords
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