STUDIES OF THE REACTION SYSTEM [SCCL3(THF)(3)]-SBCL5-L (THF=TETRAHYDIOFURAN, L=4,7,13,16,21,24-HEXAOXA-1,10-DIAZABICYCLO[8.8.8]HEXACOSANE) - UNEXPECTED FORMATION AND CRYSTAL-STRUCTURE OF [H(2)L]CL-2-CENTER-DOT-SCCL3(H2O)(3)CENTER-DOT-3H(2)O

The reaction system [ScCl3(thf)(3)]-SbCl5-cryptand 222 (L) (thf = tetrahydrofuran, cryptand 222 = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) has been studied as a possible route to scandium(III)-cryptate complexation. The compound [H(2)L]Cl-2 . ScCl3(H2O)(3) . 3H(2)O 1 was isolated as yellow crystals. Microanalytical and spectroscopic (IR,H-1) data and a crystal-structure determination provided complete identification of 1. Crystals are monoclinic. space group C2/c with a = 29.008(14), b = 8.369(7), c = 26.356(14) Angstrom, beta = 94.6(1)degrees and Z = 8. The molecular structure consists of discrete [H(2)L](2+) cations, two accompanying chloride anions, a molecule of [ScCl3(H2O)(3)] and three water molecules trapped in the lattice. The diprotonated di-endo cryptand cation binds two protons within the intramolecular cavity with an N ... N separation of 6.34(4) Angstrom. The encapsulated protons are covalently bound to the nitrogen atoms and each NH centre is involved in weak intracavity hydrogen-bonding interactions with the three adjacent oxygen atoms [N ... O 2.84(2) (two). 2.83(2) Angstrom and 2.74(2), 2.71(2), 2.72(2) Angstrom]. The structure of the molecular adduct [ScCl3(H2O)(3)] shows a central six-co-ordinate scandium atom with a near-idealised mer-octahedral geometry [mean Sc-Cl 2.417(7), mean Sc-O 2.122(14) Angstrom]