Crystal structure of a uranyl/p-tert-butylcalix[5]-arene complex

The synthesis and crystal structure of the inclusion complex between uranyl and p-tertbutylcalix[5]arene are reported. [UO2(p-tert-butylcalix[5]arene-4H)](2-). 2HNEt(3)(+). 2MeOH (1) crystallizes in the monoclinic space group C2/c, a = 30.06(2), b = 18.20(3), c = 31.35(2) Angstrom, beta = 128.51(6)degrees, V = 13423(40) Angstrom(3), Z = 8. Refinement led to a final conventional R value of 0.043 for 4155 reflections. The uranyl ion is bonded, in its equatorial plane, to the five oxygen atoms of the calixarene, four of which are deprotonated. A protonated triethylamine molecule is located inside the calixarene cavity and hydrogen bonded to a uranyl oxygen atom, and another one outside and hydrogen bonded to a calixarene oxygen atom. The calixarene conformation is the usual cone one.