Macrocycle complexation chemistry. 37. The isolation and crystallographic characterization of the U4+ and UO2+ extraction complexes [(H5O2)(dicyclohexano-24-crown-8)]2[U02Cl4]⁗MeOH and [(H5O2) (dicyclohexano-24-crown-8)]2[UCl6]⁗MeOH

The reaction of dicyclohexano-24-crown-8 with UCl₄ in 3/1 THF:MeOH under anhydrous conditions and with exposure to air, resulted in the isolation of the hydronium ion complexes, [(H₅O₂)(dicyclohexano-24-crown-8)]₂[UO₂Cl₄]-MeOH and [(H₅O₂)(dicyclohexano-24-crown-8)]₂[UCI₆]-MeOH. The [UO₂Cl₄]^2? complex crystallizes in the monoclinic space group,P2₁/n, witha = 15.200(8),b = 26.565(9),c = 16.977(8)Å, β = 95.89(6)° andD _calc = 1.40 g cm^?3 forZ = 4 formula units. A finalR value of 0.051 was obtained utilizing 5913 independent observed [F _o ≥ 5σ(F _o)] reflections. One ether is complexed by an ordered H₅O _inf2 ^sup+ ion, while the second crown ether is hydrogen bonded to a disordered H₅O _inf2 ^sup+ ion. The [UCl₆]^2? complex is tetragonal,P4/n, with (at ?150°C)a = 16.320(4),c = 12.542(2)Å andD _calc = 1.47 g cm^?1 forZ = 2. A finalR value of 0.038 was obtained utilizing 2466 observed reflections. The anion resides on a four-fold axis and the crown ether cation around a crystallographic two-fold axis. The H₅O _inf2 ^sup+ ion is disordered into two orientations within the macrocycle cavity. All three crystallographically independent crown ether environments in these two structures have essentially identical conformations.