No abstract

No abstract

Measurements of the nuclear magnetic shielding of FlO and HI are reported for a number of their respective binary covalent compounds. The applied fields required for the FI9 and HI nuclear magnetic resonances, at fixed frequency, vary in these compounds over a range of 3.98 and 0.122 gauss, respectively, at fields of about 6365 gauss. These ranges are of the same order of magnitude as the theoretical internal diamagnetic corrections for the unbound fluorine and hydrogen atoms. The dependence of nuclear magnetic shielding on the electronic structures of the molecules is discussed qualitatively and some general correlations indicated. One such correlation is that the magnetic shielding of the Fl9 nucleus decreases with increasing electronegativity of the atom to which the fluorine is bonded. This and other correlations differ in degree for the proton. The differences may arise from the relatively greater importance of the diamagnetic shielding term for the proton. Specific information regarding molecular and electronic structure is provided in several instances. The tetragonal pyramid structure for IF. is confirmed and a similar structure demonstrated for BrF •. The appearance of double FlO resonance lines in PF., IF., and BrF. indicates nonequivalent electronic distributions in the structurally distinguishable bonds. The measurements were facilitated by a large permanent magnet, the design and field homogenization of which are described. 4 G. E. Pake, Am. J. Phys. 18,438,473 (1950), gives a general review and bibliography of most work prior to 1950.

No abstract

No abstract