Crystal structure of an uranyl/p-tert-butyl calix[6]arene dimer

Abstract
The crystal structure of [UO2(p-tert-butylcalix[6]arene-4H)]2. (HNEt3)2.(H3O)2.6CH3CN is described. This compound crystallizes in the monoclinic space group P21/n with a = 19.183(5), b = 17.726(9), c = 23.206(9) Å, β = 106.16(3)°, V = 7579(5) Å3, Z = 2. 414 parameters were refined to a residual of 0.062 for 3475 observed reflections (I > 3[sgrave](I)). Two four-fold deprotonated calixarene moieties face each other and are held together by two uranyl ions, each of them bonded to two deprotonated phenolic oxygen atoms of each calixarene moiety (uranyl equatorial geometry, approximately square planar). Two protonated triethylamine molecules form possible hydrogen-bonds with two calixarene oxygen atoms. A hydronium ion is located in each calixarene cavity and forms possible hydrogen bonds with the uncomplexed phenolic oxygen atoms and the nitrogen atom of an acetonitrile molecule.