Activation of SO 2 and CO 2 by Trivalent Uranium Leading to Sulfite/Dithionite and Carbonate/Oxalate Complexes
Résumé
The first sulfite [{((nP,MeArO)3tacn)UIV}2(μ‐κ1:κ2‐SO3)] (tacn=triazacyclononane) and dithionite [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐S2O4)] complexes of uranium from reaction with gaseous SO2 have been prepared. Additionally, the reductive activation of CO2 was investigated with respect to the rare oxalate [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐C2O4)] formation. This ultimately provides the unique S2O42−/C2O42− and SO32−/CO32− complex pairs. All new complexes were characterized by a combination of single‐crystal X‐ray diffraction, elemental analysis, UV/Vis/NIR electronic absorption, IR vibrational, and 1H NMR spectroscopy, as well as magnetization (VT SQUID) studies. Moreover, density functional theory (DFT) calculations were carried out to gain further insight into the reaction mechanisms. All observations, together with DFT, support the assumption that SO2 and CO2 show similar (dithionite/oxalate) to analogous (sulfite/carbonate) activation behavior with uranium complexes.