LANTHANIDE ION COMPLEXES OF CALIXARENES .7. BIMETALLIC LANTHANIDE COMPLEXES OF PARA-TERT-BUTYLCALIX[8]ARENE FROM DIMETHYL-SULFOXIDE SOLUTIONS

Reaction of Ln(ClO4)3.xdmso (dmso denotes dimethyl sulfoxide) with a warm p-t-butylcalix[8]arene (L) slurry in acetone/dmso yields crystalline 2:1 Ln/ligand adducts, characterized as dmso solvates and established to be [Ln2(L-6H)(dmso)5].approximately 2dmso by single-crystal X-ray studies at c. 295 K for Ln = La, Eu, Tm and Lu. All complexes are isomorphous, orthorhombic, Pcnb, a almost-equal-to 34, b almost-equal-to 23, c almost-equal-to 14 angstrom, Z 4, with a similar complex molecule in each case, one half comprising the asymmetric unit; the second half is generated by a crystallographic twofold axis. The two lanthanide atoms are encompassed by the macrocycle and are eight coordinate, involving phenolic and dmso O-donor atoms, five of the former (two bridging) and three of the latter (one bridging). The array closely resembles that found in analogous dmf solvent adducts: the bridging dmso lies on the crystallographic twofold axis through the complex, its peripheral atoms being modelled by disorder.