T. Drews et al., The Cl2O2+ cation: Preparation and structural investigation of Cl2O2+SbF6-and Cl2O2+Sb2F11-, J AM CHEM S, 121(18), 1999, pp. 4379-4384
Cl-2 reacts with O2+SbF6- in anhydrous HF, forming subsequently a violet, a
blue, and a yellow solution. Crystals from the violet solution are identif
ied as Cl2O2+SbF6- or Cl2O2+Sb2F11- by means of single-crystal structural d
eterminations, Raman spectroscopy, magnetic and EPR measurements, and ab in
itio calculations. The cation has a planar trapezoid structure with Cl-Cl d
istances of 190.9(1)-191.6(5) pm, O-O distances of 118.5(11)-120.7(5) pm, a
nd Cl-O distances of 240.8(4)-242.8(4) pm. The bonding between the two part
s of the cation may be described as a pi*-pi* interaction, resulting in a c
harge transfer of about 0.6 electrons with respect to isolated Cl-2(+) and
O-2 fragments. The bonding of O-2 to Cl-2(+) is reversible, as is shown by
O-18 isotope exchange. The nature of the blue solution remains unknown. Bot
h deeply colored compounds rum into yellow Cl-3(+) if warmed to room temper
ature, especially in the presence of excess Cl-2. The Cl-3(+) cation is sym
metrical and bent with Cl-Cl = 197.23-199.44 pm and Cl-Cl-Cl = 104.51(10)-1
05.62(7)degrees.