Abstract
The identical temperature dependence of the pmr spectra of Zr(BH4)4 and Hf(BH4)4 is due to the variable rate of 10B and 11B quadrupolar spin-lattice relaxation. Intramolecular rearrangement processes are still rapid at -80°. Quantitative analysis of the spectra as a function of solution viscosity yields results at least partially in accord with the hydrodynamic model for molecular reorientation, though inertial effects are also probably operative. Within experimental error, both molecules have the same nuclear quadrupole coupling constants, which are estimated to be: 10B, 3.5 ± 0.6 MHz; 11B, 1.7 ± 0.3 MHz, and the same activation energies for molecular reorientation, 3.1 ± 0.1 kcal/mol.
| Original language | English |
|---|---|
| Pages (from-to) | 1542-1550 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 94 |
| Issue number | 5 |
| Publication status | Published - 1972 |
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Cite this
Structure and dynamics in metal tetrahydroborates. I. Nuclear magnetic resonance studies of zirconium and hafnium tetrakis(tetrahydroborates). / Marks, Tobin J; Shimp, Lawrence A.
In: Journal of the American Chemical Society, Vol. 94, No. 5, 1972, p. 1542-1550.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structure and dynamics in metal tetrahydroborates. I. Nuclear magnetic resonance studies of zirconium and hafnium tetrakis(tetrahydroborates)
AU - Marks, Tobin J
AU - Shimp, Lawrence A.
PY - 1972
Y1 - 1972
N2 - The identical temperature dependence of the pmr spectra of Zr(BH4)4 and Hf(BH4)4 is due to the variable rate of 10B and 11B quadrupolar spin-lattice relaxation. Intramolecular rearrangement processes are still rapid at -80°. Quantitative analysis of the spectra as a function of solution viscosity yields results at least partially in accord with the hydrodynamic model for molecular reorientation, though inertial effects are also probably operative. Within experimental error, both molecules have the same nuclear quadrupole coupling constants, which are estimated to be: 10B, 3.5 ± 0.6 MHz; 11B, 1.7 ± 0.3 MHz, and the same activation energies for molecular reorientation, 3.1 ± 0.1 kcal/mol.
AB - The identical temperature dependence of the pmr spectra of Zr(BH4)4 and Hf(BH4)4 is due to the variable rate of 10B and 11B quadrupolar spin-lattice relaxation. Intramolecular rearrangement processes are still rapid at -80°. Quantitative analysis of the spectra as a function of solution viscosity yields results at least partially in accord with the hydrodynamic model for molecular reorientation, though inertial effects are also probably operative. Within experimental error, both molecules have the same nuclear quadrupole coupling constants, which are estimated to be: 10B, 3.5 ± 0.6 MHz; 11B, 1.7 ± 0.3 MHz, and the same activation energies for molecular reorientation, 3.1 ± 0.1 kcal/mol.
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UR - http://www.scopus.com/inward/citedby.url?scp=0001276567&partnerID=8YFLogxK
M3 - Article
VL - 94
SP - 1542
EP - 1550
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 5
ER -