CRYSTAL-STRUCTURE OF AN URANYL P-TERT-BUTYL CALIX[6]ARENE DIMER/

The crystal structure of [UO2(p-tert-butylcalix[6]arene-4H)](2). (HNEt (3))(2).(H3O)(2).6CH(3)CN is described. This compound crystallizes in the monoclinic space group P2(1)/n with a = 19.183(5), b = 17.726(9), c = 23.206(9) Angstrom, beta = 106.16(3)degrees, V = 7579(5) Angstrom( 3), Z = 2. 414 parameters were refined to a residual of 0.062 for 3475 observed reflections (I > 3 sigma(I)). Two four-fold deprotonated cal ixarene moieties face each other and are held together by two uranyl i ons, each of them bonded to two deprotonated phenolic oxygen atoms of each calixarene moiety (uranyl equatorial geometry, approximately squa re planar), Two protonated triethylamine molecules form possible hydro gen-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 acetonit rile molecule.