Infrared spectroscopy of extreme coordination: the carbonyls of U(+) and UO(2)(+).
Uranium and uranium dioxide carbonyl cations produced by laser vaporization are studied with mass-selected ion infrared spectroscopy in the C-O stretching region. Dissociation patterns, spectra, and quantum chemical calculations establish that the fully coordinated ions are U(CO)(8)(+) and UO(2)(CO)(5)(+), with D(4d) square antiprism and D(5h) pentagonal bipyramid structures. Back-bonding in U(CO)(8)(+) causes a red-shifted CO stretch, but back-donation is inefficient for UO(2)(CO)(5)(+), producing a blue-shifted CO stretch characteristic of nonclassical carbonyls.
Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States.
Allen M
AM
Ricks
Laura
L
Gagliardi
Michael A
MA
Duncan