A uranyl ion complex of N-methyl-p-tert-butyldihomoammoniocalix[4]-arene with diaquadipyridinelithium as counter-ion

The title complex, diaquadipyridinelithium (N-methyl-p-tert-butyldihomoammoniocalix[4] arene-kappa(4) O) dioxouranium(VI) tripyridine solvate monohydrate, [Li(C5H5N)(2)(H2O)(2)][UO2( C46H58NO4)].3C(5)H(5)N.H2O, contains an 'internal' tetraphenoxide-coordinated uranyl complex of the macrocycle, in which the protonated N atom is involved in an intramolecular hydrogen bond with the uranyl oxo group located in the cavity. The Li+ ion is in a tetrahedral environment and its two water ligands are involved in hydrogen bonds with two phenoxide O atoms, two pyridine molecules and one water molecule. This arrangement is compared with those obtained previously for other homoazacalixarenes and also for homooxacalixarenes in the presence of alkali metal hydroxides.