Crystal Structure of the Uranyl Ion Complex of p-tert-Butylcalix[7]arene

Abstract

The synthesis and crystal structure of the uranyl ion complex of p-tert-butylcalix[7]arene are reported. (UO₂ ²⁺)(LH₃ ^4-)(HNEt₃ ⁺)₂·CH₃NO₂·CH₃OH (1), in which LH₇ is p-tert-butylcalix[7]arene, crystallizes in the monoclinic space group P2₁/ _c , a = 22.515(6), b = 27.660(5), c = 18.608(6) Å, β = 113.98(2)°, V = 10588(10) ų, Z = 4. Refinement led to a final conventional R value of 0.082 for 6784 reflections. The calixarene adopts the same geometry as in its uncomplexed form, i.e., it may be considered a ditopic receptor formed by the angular fusion of two cone-like cavities involving four and three phenolic units. The uranyl ion is at the centre of the base of the larger cavity and is bound to four deprotonated oxygen atoms in its equatorial plane.

Key Words:

• Calixarenes
• uranyl ion complex
• crystal structure