The magnetic shielding and quadrupole interaction constants of V-51 nuclei
in the low-temperature (nonconducting) phase of vanadium dioxide are determ
ined by magnetic resonance on the (51V) nuclei. It is shown that the metal-
insulator transition in VO2 is accompanied by a change in the sign of the m
agnetic shielding constant and by an electronic transition 2V(4+)--> V3++V5
+, which is accompanied by a charge ordering in the cation sublattice. (C)
2000 American Institute of Physics. [S1063-777X(00)01102-6].