Bis{bis[5-tert-butyl-2-oxido-3-(1-pyridiniomethyl)phenyl]methane}-dioxouranium bis(trifluoromethanesulfonate) pyridine disolvate:: a uranyl bis(diphenoxide) complex resulting from homooxacalixarene cleavage

The title compound, [UO2(C33H38N2O2)(2)](CF3SO3)(2).2C(5)H(5)N, has been obtained by reaction of U-IV trifluoromethanesulfonate with p-tert-butyltetrahomodioxacalix[4] arene in pyridine. The uranyl ion lies on an inversion centre and is bound to two O atoms from each diphenoxide ligand, which gives the usual square-planar equatorial environment. The zwitterionic diphenoxide species results from nucleophilic attack by pyridine on the benzylic ether C atoms of the homooxacalixarene, assisted by initial U coordination to the ether groups, with subsequent metal oxidation giving the uranyl moiety.